diff options
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 5057 |
1 files changed, 3531 insertions, 1526 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index faf357eaf0ce..f7c565f11a98 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1,15 +1,13 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2009 Red Hat, Inc. - * - * This work is licensed under the terms of the GNU GPL, version 2. See - * the COPYING file in the top-level directory. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/mm.h> #include <linux/sched.h> -#include <linux/sched/coredump.h> +#include <linux/sched/mm.h> #include <linux/sched/numa_balancing.h> #include <linux/highmem.h> #include <linux/hugetlb.h> @@ -19,10 +17,11 @@ #include <linux/shrinker.h> #include <linux/mm_inline.h> #include <linux/swapops.h> +#include <linux/backing-dev.h> #include <linux/dax.h> +#include <linux/mm_types.h> #include <linux/khugepaged.h> #include <linux/freezer.h> -#include <linux/pfn_t.h> #include <linux/mman.h> #include <linux/memremap.h> #include <linux/pagemap.h> @@ -33,10 +32,21 @@ #include <linux/page_idle.h> #include <linux/shmem_fs.h> #include <linux/oom.h> +#include <linux/numa.h> +#include <linux/page_owner.h> +#include <linux/sched/sysctl.h> +#include <linux/memory-tiers.h> +#include <linux/compat.h> +#include <linux/pgalloc.h> +#include <linux/pgalloc_tag.h> +#include <linux/pagewalk.h> #include <asm/tlb.h> -#include <asm/pgalloc.h> #include "internal.h" +#include "swap.h" + +#define CREATE_TRACE_POINTS +#include <trace/events/thp.h> /* * By default, transparent hugepage support is disabled in order to avoid @@ -57,49 +67,178 @@ unsigned long transparent_hugepage_flags __read_mostly = (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); -static struct shrinker deferred_split_shrinker; +static struct shrinker *deferred_split_shrinker; +static unsigned long deferred_split_count(struct shrinker *shrink, + struct shrink_control *sc); +static unsigned long deferred_split_scan(struct shrinker *shrink, + struct shrink_control *sc); +static bool split_underused_thp = true; static atomic_t huge_zero_refcount; -struct page *huge_zero_page __read_mostly; +struct folio *huge_zero_folio __read_mostly; +unsigned long huge_zero_pfn __read_mostly = ~0UL; +unsigned long huge_anon_orders_always __read_mostly; +unsigned long huge_anon_orders_madvise __read_mostly; +unsigned long huge_anon_orders_inherit __read_mostly; +static bool anon_orders_configured __initdata; + +static inline bool file_thp_enabled(struct vm_area_struct *vma) +{ + struct inode *inode; + + if (!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) + return false; + + if (!vma->vm_file) + return false; + + inode = file_inode(vma->vm_file); + + return !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode); +} -bool transparent_hugepage_enabled(struct vm_area_struct *vma) +unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, + vm_flags_t vm_flags, + enum tva_type type, + unsigned long orders) { + const bool smaps = type == TVA_SMAPS; + const bool in_pf = type == TVA_PAGEFAULT; + const bool forced_collapse = type == TVA_FORCED_COLLAPSE; + unsigned long supported_orders; + + /* Check the intersection of requested and supported orders. */ if (vma_is_anonymous(vma)) - return __transparent_hugepage_enabled(vma); - if (vma_is_shmem(vma) && shmem_huge_enabled(vma)) - return __transparent_hugepage_enabled(vma); + supported_orders = THP_ORDERS_ALL_ANON; + else if (vma_is_special_huge(vma)) + supported_orders = THP_ORDERS_ALL_SPECIAL; + else + supported_orders = THP_ORDERS_ALL_FILE_DEFAULT; - return false; + orders &= supported_orders; + if (!orders) + return 0; + + if (!vma->vm_mm) /* vdso */ + return 0; + + if (thp_disabled_by_hw() || vma_thp_disabled(vma, vm_flags, forced_collapse)) + return 0; + + /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ + if (vma_is_dax(vma)) + return in_pf ? orders : 0; + + /* + * khugepaged special VMA and hugetlb VMA. + * Must be checked after dax since some dax mappings may have + * VM_MIXEDMAP set. + */ + if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED)) + return 0; + + /* + * Check alignment for file vma and size for both file and anon vma by + * filtering out the unsuitable orders. + * + * Skip the check for page fault. Huge fault does the check in fault + * handlers. + */ + if (!in_pf) { + int order = highest_order(orders); + unsigned long addr; + + while (orders) { + addr = vma->vm_end - (PAGE_SIZE << order); + if (thp_vma_suitable_order(vma, addr, order)) + break; + order = next_order(&orders, order); + } + + if (!orders) + return 0; + } + + /* + * Enabled via shmem mount options or sysfs settings. + * Must be done before hugepage flags check since shmem has its + * own flags. + */ + if (!in_pf && shmem_file(vma->vm_file)) + return orders & shmem_allowable_huge_orders(file_inode(vma->vm_file), + vma, vma->vm_pgoff, 0, + forced_collapse); + + if (!vma_is_anonymous(vma)) { + /* + * Enforce THP collapse requirements as necessary. Anonymous vmas + * were already handled in thp_vma_allowable_orders(). + */ + if (!forced_collapse && + (!hugepage_global_enabled() || (!(vm_flags & VM_HUGEPAGE) && + !hugepage_global_always()))) + return 0; + + /* + * Trust that ->huge_fault() handlers know what they are doing + * in fault path. + */ + if (((in_pf || smaps)) && vma->vm_ops->huge_fault) + return orders; + /* Only regular file is valid in collapse path */ + if (((!in_pf || smaps)) && file_thp_enabled(vma)) + return orders; + return 0; + } + + if (vma_is_temporary_stack(vma)) + return 0; + + /* + * THPeligible bit of smaps should show 1 for proper VMAs even + * though anon_vma is not initialized yet. + * + * Allow page fault since anon_vma may be not initialized until + * the first page fault. + */ + if (!vma->anon_vma) + return (smaps || in_pf) ? orders : 0; + + return orders; } -static struct page *get_huge_zero_page(void) +static bool get_huge_zero_folio(void) { - struct page *zero_page; + struct folio *zero_folio; retry: if (likely(atomic_inc_not_zero(&huge_zero_refcount))) - return READ_ONCE(huge_zero_page); + return true; - zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, + zero_folio = folio_alloc((GFP_TRANSHUGE | __GFP_ZERO | __GFP_ZEROTAGS) & + ~__GFP_MOVABLE, HPAGE_PMD_ORDER); - if (!zero_page) { + if (!zero_folio) { count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); - return NULL; + return false; } - count_vm_event(THP_ZERO_PAGE_ALLOC); + /* Ensure zero folio won't have large_rmappable flag set. */ + folio_clear_large_rmappable(zero_folio); preempt_disable(); - if (cmpxchg(&huge_zero_page, NULL, zero_page)) { + if (cmpxchg(&huge_zero_folio, NULL, zero_folio)) { preempt_enable(); - __free_pages(zero_page, compound_order(zero_page)); + folio_put(zero_folio); goto retry; } + WRITE_ONCE(huge_zero_pfn, folio_pfn(zero_folio)); /* We take additional reference here. It will be put back by shrinker */ atomic_set(&huge_zero_refcount, 2); preempt_enable(); - return READ_ONCE(huge_zero_page); + count_vm_event(THP_ZERO_PAGE_ALLOC); + return true; } -static void put_huge_zero_page(void) +static void put_huge_zero_folio(void) { /* * Counter should never go to zero here. Only shrinker can put @@ -108,62 +247,70 @@ static void put_huge_zero_page(void) BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); } -struct page *mm_get_huge_zero_page(struct mm_struct *mm) +struct folio *mm_get_huge_zero_folio(struct mm_struct *mm) { - if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) - return READ_ONCE(huge_zero_page); + if (IS_ENABLED(CONFIG_PERSISTENT_HUGE_ZERO_FOLIO)) + return huge_zero_folio; + + if (mm_flags_test(MMF_HUGE_ZERO_FOLIO, mm)) + return READ_ONCE(huge_zero_folio); - if (!get_huge_zero_page()) + if (!get_huge_zero_folio()) return NULL; - if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) - put_huge_zero_page(); + if (mm_flags_test_and_set(MMF_HUGE_ZERO_FOLIO, mm)) + put_huge_zero_folio(); - return READ_ONCE(huge_zero_page); + return READ_ONCE(huge_zero_folio); } -void mm_put_huge_zero_page(struct mm_struct *mm) +void mm_put_huge_zero_folio(struct mm_struct *mm) { - if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) - put_huge_zero_page(); + if (IS_ENABLED(CONFIG_PERSISTENT_HUGE_ZERO_FOLIO)) + return; + + if (mm_flags_test(MMF_HUGE_ZERO_FOLIO, mm)) + put_huge_zero_folio(); } -static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, - struct shrink_control *sc) +static unsigned long shrink_huge_zero_folio_count(struct shrinker *shrink, + struct shrink_control *sc) { /* we can free zero page only if last reference remains */ return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; } -static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, - struct shrink_control *sc) +static unsigned long shrink_huge_zero_folio_scan(struct shrinker *shrink, + struct shrink_control *sc) { if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { - struct page *zero_page = xchg(&huge_zero_page, NULL); - BUG_ON(zero_page == NULL); - __free_pages(zero_page, compound_order(zero_page)); + struct folio *zero_folio = xchg(&huge_zero_folio, NULL); + BUG_ON(zero_folio == NULL); + WRITE_ONCE(huge_zero_pfn, ~0UL); + folio_put(zero_folio); return HPAGE_PMD_NR; } return 0; } -static struct shrinker huge_zero_page_shrinker = { - .count_objects = shrink_huge_zero_page_count, - .scan_objects = shrink_huge_zero_page_scan, - .seeks = DEFAULT_SEEKS, -}; +static struct shrinker *huge_zero_folio_shrinker; #ifdef CONFIG_SYSFS static ssize_t enabled_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { + const char *output; + if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) - return sprintf(buf, "[always] madvise never\n"); - else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags)) - return sprintf(buf, "always [madvise] never\n"); + output = "[always] madvise never"; + else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, + &transparent_hugepage_flags)) + output = "always [madvise] never"; else - return sprintf(buf, "always madvise [never]\n"); + output = "always madvise [never]"; + + return sysfs_emit(buf, "%s\n", output); } static ssize_t enabled_store(struct kobject *kobj, @@ -172,16 +319,13 @@ static ssize_t enabled_store(struct kobject *kobj, { ssize_t ret = count; - if (!memcmp("always", buf, - min(sizeof("always")-1, count))) { + if (sysfs_streq(buf, "always")) { clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); - } else if (!memcmp("madvise", buf, - min(sizeof("madvise")-1, count))) { + } else if (sysfs_streq(buf, "madvise")) { clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); - } else if (!memcmp("never", buf, - min(sizeof("never")-1, count))) { + } else if (sysfs_streq(buf, "never")) { clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); } else @@ -194,15 +338,15 @@ static ssize_t enabled_store(struct kobject *kobj, } return ret; } -static struct kobj_attribute enabled_attr = - __ATTR(enabled, 0644, enabled_show, enabled_store); + +static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); ssize_t single_hugepage_flag_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf, - enum transparent_hugepage_flag flag) + struct kobj_attribute *attr, char *buf, + enum transparent_hugepage_flag flag) { - return sprintf(buf, "%d\n", - !!test_bit(flag, &transparent_hugepage_flags)); + return sysfs_emit(buf, "%d\n", + !!test_bit(flag, &transparent_hugepage_flags)); } ssize_t single_hugepage_flag_store(struct kobject *kobj, @@ -230,47 +374,51 @@ ssize_t single_hugepage_flag_store(struct kobject *kobj, static ssize_t defrag_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { - if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) - return sprintf(buf, "[always] defer defer+madvise madvise never\n"); - if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) - return sprintf(buf, "always [defer] defer+madvise madvise never\n"); - if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) - return sprintf(buf, "always defer [defer+madvise] madvise never\n"); - if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) - return sprintf(buf, "always defer defer+madvise [madvise] never\n"); - return sprintf(buf, "always defer defer+madvise madvise [never]\n"); + const char *output; + + if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, + &transparent_hugepage_flags)) + output = "[always] defer defer+madvise madvise never"; + else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, + &transparent_hugepage_flags)) + output = "always [defer] defer+madvise madvise never"; + else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, + &transparent_hugepage_flags)) + output = "always defer [defer+madvise] madvise never"; + else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, + &transparent_hugepage_flags)) + output = "always defer defer+madvise [madvise] never"; + else + output = "always defer defer+madvise madvise [never]"; + + return sysfs_emit(buf, "%s\n", output); } static ssize_t defrag_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { - if (!memcmp("always", buf, - min(sizeof("always")-1, count))) { + if (sysfs_streq(buf, "always")) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); - } else if (!memcmp("defer+madvise", buf, - min(sizeof("defer+madvise")-1, count))) { + } else if (sysfs_streq(buf, "defer+madvise")) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); - } else if (!memcmp("defer", buf, - min(sizeof("defer")-1, count))) { + } else if (sysfs_streq(buf, "defer")) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); - } else if (!memcmp("madvise", buf, - min(sizeof("madvise")-1, count))) { + } else if (sysfs_streq(buf, "madvise")) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); - } else if (!memcmp("never", buf, - min(sizeof("never")-1, count))) { + } else if (sysfs_streq(buf, "never")) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); @@ -280,14 +428,13 @@ static ssize_t defrag_store(struct kobject *kobj, return count; } -static struct kobj_attribute defrag_attr = - __ATTR(defrag, 0644, defrag_show, defrag_store); +static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); static ssize_t use_zero_page_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf) + struct kobj_attribute *attr, char *buf) { return single_hugepage_flag_show(kobj, attr, buf, - TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); + TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); } static ssize_t use_zero_page_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) @@ -295,46 +442,46 @@ static ssize_t use_zero_page_store(struct kobject *kobj, return single_hugepage_flag_store(kobj, attr, buf, count, TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); } -static struct kobj_attribute use_zero_page_attr = - __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); +static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page); static ssize_t hpage_pmd_size_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf) + struct kobj_attribute *attr, char *buf) { - return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE); + return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); } static struct kobj_attribute hpage_pmd_size_attr = __ATTR_RO(hpage_pmd_size); -#ifdef CONFIG_DEBUG_VM -static ssize_t debug_cow_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf) +static ssize_t split_underused_thp_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) { - return single_hugepage_flag_show(kobj, attr, buf, - TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); + return sysfs_emit(buf, "%d\n", split_underused_thp); } -static ssize_t debug_cow_store(struct kobject *kobj, - struct kobj_attribute *attr, - const char *buf, size_t count) + +static ssize_t split_underused_thp_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) { - return single_hugepage_flag_store(kobj, attr, buf, count, - TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); + int err = kstrtobool(buf, &split_underused_thp); + + if (err < 0) + return err; + + return count; } -static struct kobj_attribute debug_cow_attr = - __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); -#endif /* CONFIG_DEBUG_VM */ + +static struct kobj_attribute split_underused_thp_attr = __ATTR( + shrink_underused, 0644, split_underused_thp_show, split_underused_thp_store); static struct attribute *hugepage_attr[] = { &enabled_attr.attr, &defrag_attr.attr, &use_zero_page_attr.attr, &hpage_pmd_size_attr.attr, -#if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) +#ifdef CONFIG_SHMEM &shmem_enabled_attr.attr, #endif -#ifdef CONFIG_DEBUG_VM - &debug_cow_attr.attr, -#endif + &split_underused_thp_attr.attr, NULL, }; @@ -342,9 +489,303 @@ static const struct attribute_group hugepage_attr_group = { .attrs = hugepage_attr, }; +static void hugepage_exit_sysfs(struct kobject *hugepage_kobj); +static void thpsize_release(struct kobject *kobj); +static DEFINE_SPINLOCK(huge_anon_orders_lock); +static LIST_HEAD(thpsize_list); + +static ssize_t anon_enabled_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + int order = to_thpsize(kobj)->order; + const char *output; + + if (test_bit(order, &huge_anon_orders_always)) + output = "[always] inherit madvise never"; + else if (test_bit(order, &huge_anon_orders_inherit)) + output = "always [inherit] madvise never"; + else if (test_bit(order, &huge_anon_orders_madvise)) + output = "always inherit [madvise] never"; + else + output = "always inherit madvise [never]"; + + return sysfs_emit(buf, "%s\n", output); +} + +static ssize_t anon_enabled_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int order = to_thpsize(kobj)->order; + ssize_t ret = count; + + if (sysfs_streq(buf, "always")) { + spin_lock(&huge_anon_orders_lock); + clear_bit(order, &huge_anon_orders_inherit); + clear_bit(order, &huge_anon_orders_madvise); + set_bit(order, &huge_anon_orders_always); + spin_unlock(&huge_anon_orders_lock); + } else if (sysfs_streq(buf, "inherit")) { + spin_lock(&huge_anon_orders_lock); + clear_bit(order, &huge_anon_orders_always); + clear_bit(order, &huge_anon_orders_madvise); + set_bit(order, &huge_anon_orders_inherit); + spin_unlock(&huge_anon_orders_lock); + } else if (sysfs_streq(buf, "madvise")) { + spin_lock(&huge_anon_orders_lock); + clear_bit(order, &huge_anon_orders_always); + clear_bit(order, &huge_anon_orders_inherit); + set_bit(order, &huge_anon_orders_madvise); + spin_unlock(&huge_anon_orders_lock); + } else if (sysfs_streq(buf, "never")) { + spin_lock(&huge_anon_orders_lock); + clear_bit(order, &huge_anon_orders_always); + clear_bit(order, &huge_anon_orders_inherit); + clear_bit(order, &huge_anon_orders_madvise); + spin_unlock(&huge_anon_orders_lock); + } else + ret = -EINVAL; + + if (ret > 0) { + int err; + + err = start_stop_khugepaged(); + if (err) + ret = err; + } + return ret; +} + +static struct kobj_attribute anon_enabled_attr = + __ATTR(enabled, 0644, anon_enabled_show, anon_enabled_store); + +static struct attribute *anon_ctrl_attrs[] = { + &anon_enabled_attr.attr, + NULL, +}; + +static const struct attribute_group anon_ctrl_attr_grp = { + .attrs = anon_ctrl_attrs, +}; + +static struct attribute *file_ctrl_attrs[] = { +#ifdef CONFIG_SHMEM + &thpsize_shmem_enabled_attr.attr, +#endif + NULL, +}; + +static const struct attribute_group file_ctrl_attr_grp = { + .attrs = file_ctrl_attrs, +}; + +static struct attribute *any_ctrl_attrs[] = { + NULL, +}; + +static const struct attribute_group any_ctrl_attr_grp = { + .attrs = any_ctrl_attrs, +}; + +static const struct kobj_type thpsize_ktype = { + .release = &thpsize_release, + .sysfs_ops = &kobj_sysfs_ops, +}; + +DEFINE_PER_CPU(struct mthp_stat, mthp_stats) = {{{0}}}; + +static unsigned long sum_mthp_stat(int order, enum mthp_stat_item item) +{ + unsigned long sum = 0; + int cpu; + + for_each_possible_cpu(cpu) { + struct mthp_stat *this = &per_cpu(mthp_stats, cpu); + + sum += this->stats[order][item]; + } + + return sum; +} + +#define DEFINE_MTHP_STAT_ATTR(_name, _index) \ +static ssize_t _name##_show(struct kobject *kobj, \ + struct kobj_attribute *attr, char *buf) \ +{ \ + int order = to_thpsize(kobj)->order; \ + \ + return sysfs_emit(buf, "%lu\n", sum_mthp_stat(order, _index)); \ +} \ +static struct kobj_attribute _name##_attr = __ATTR_RO(_name) + +DEFINE_MTHP_STAT_ATTR(anon_fault_alloc, MTHP_STAT_ANON_FAULT_ALLOC); +DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK); +DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); +DEFINE_MTHP_STAT_ATTR(zswpout, MTHP_STAT_ZSWPOUT); +DEFINE_MTHP_STAT_ATTR(swpin, MTHP_STAT_SWPIN); +DEFINE_MTHP_STAT_ATTR(swpin_fallback, MTHP_STAT_SWPIN_FALLBACK); +DEFINE_MTHP_STAT_ATTR(swpin_fallback_charge, MTHP_STAT_SWPIN_FALLBACK_CHARGE); +DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT); +DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK); +#ifdef CONFIG_SHMEM +DEFINE_MTHP_STAT_ATTR(shmem_alloc, MTHP_STAT_SHMEM_ALLOC); +DEFINE_MTHP_STAT_ATTR(shmem_fallback, MTHP_STAT_SHMEM_FALLBACK); +DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE); +#endif +DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT); +DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED); +DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED); +DEFINE_MTHP_STAT_ATTR(nr_anon, MTHP_STAT_NR_ANON); +DEFINE_MTHP_STAT_ATTR(nr_anon_partially_mapped, MTHP_STAT_NR_ANON_PARTIALLY_MAPPED); + +static struct attribute *anon_stats_attrs[] = { + &anon_fault_alloc_attr.attr, + &anon_fault_fallback_attr.attr, + &anon_fault_fallback_charge_attr.attr, +#ifndef CONFIG_SHMEM + &zswpout_attr.attr, + &swpin_attr.attr, + &swpin_fallback_attr.attr, + &swpin_fallback_charge_attr.attr, + &swpout_attr.attr, + &swpout_fallback_attr.attr, +#endif + &split_deferred_attr.attr, + &nr_anon_attr.attr, + &nr_anon_partially_mapped_attr.attr, + NULL, +}; + +static struct attribute_group anon_stats_attr_grp = { + .name = "stats", + .attrs = anon_stats_attrs, +}; + +static struct attribute *file_stats_attrs[] = { +#ifdef CONFIG_SHMEM + &shmem_alloc_attr.attr, + &shmem_fallback_attr.attr, + &shmem_fallback_charge_attr.attr, +#endif + NULL, +}; + +static struct attribute_group file_stats_attr_grp = { + .name = "stats", + .attrs = file_stats_attrs, +}; + +static struct attribute *any_stats_attrs[] = { +#ifdef CONFIG_SHMEM + &zswpout_attr.attr, + &swpin_attr.attr, + &swpin_fallback_attr.attr, + &swpin_fallback_charge_attr.attr, + &swpout_attr.attr, + &swpout_fallback_attr.attr, +#endif + &split_attr.attr, + &split_failed_attr.attr, + NULL, +}; + +static struct attribute_group any_stats_attr_grp = { + .name = "stats", + .attrs = any_stats_attrs, +}; + +static int sysfs_add_group(struct kobject *kobj, + const struct attribute_group *grp) +{ + int ret = -ENOENT; + + /* + * If the group is named, try to merge first, assuming the subdirectory + * was already created. This avoids the warning emitted by + * sysfs_create_group() if the directory already exists. + */ + if (grp->name) + ret = sysfs_merge_group(kobj, grp); + if (ret) + ret = sysfs_create_group(kobj, grp); + + return ret; +} + +static struct thpsize *thpsize_create(int order, struct kobject *parent) +{ + unsigned long size = (PAGE_SIZE << order) / SZ_1K; + struct thpsize *thpsize; + int ret = -ENOMEM; + + thpsize = kzalloc(sizeof(*thpsize), GFP_KERNEL); + if (!thpsize) + goto err; + + thpsize->order = order; + + ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent, + "hugepages-%lukB", size); + if (ret) { + kfree(thpsize); + goto err; + } + + + ret = sysfs_add_group(&thpsize->kobj, &any_ctrl_attr_grp); + if (ret) + goto err_put; + + ret = sysfs_add_group(&thpsize->kobj, &any_stats_attr_grp); + if (ret) + goto err_put; + + if (BIT(order) & THP_ORDERS_ALL_ANON) { + ret = sysfs_add_group(&thpsize->kobj, &anon_ctrl_attr_grp); + if (ret) + goto err_put; + + ret = sysfs_add_group(&thpsize->kobj, &anon_stats_attr_grp); + if (ret) + goto err_put; + } + + if (BIT(order) & THP_ORDERS_ALL_FILE_DEFAULT) { + ret = sysfs_add_group(&thpsize->kobj, &file_ctrl_attr_grp); + if (ret) + goto err_put; + + ret = sysfs_add_group(&thpsize->kobj, &file_stats_attr_grp); + if (ret) + goto err_put; + } + + return thpsize; +err_put: + kobject_put(&thpsize->kobj); +err: + return ERR_PTR(ret); +} + +static void thpsize_release(struct kobject *kobj) +{ + kfree(to_thpsize(kobj)); +} + static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) { int err; + struct thpsize *thpsize; + unsigned long orders; + int order; + + /* + * Default to setting PMD-sized THP to inherit the global setting and + * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time + * constant so we have to do this here. + */ + if (!anon_orders_configured) + huge_anon_orders_inherit = BIT(PMD_ORDER); *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); if (unlikely(!*hugepage_kobj)) { @@ -364,8 +805,24 @@ static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) goto remove_hp_group; } + orders = THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_FILE_DEFAULT; + order = highest_order(orders); + while (orders) { + thpsize = thpsize_create(order, *hugepage_kobj); + if (IS_ERR(thpsize)) { + pr_err("failed to create thpsize for order %d\n", order); + err = PTR_ERR(thpsize); + goto remove_all; + } + list_add(&thpsize->node, &thpsize_list); + order = next_order(&orders, order); + } + return 0; +remove_all: + hugepage_exit_sysfs(*hugepage_kobj); + return err; remove_hp_group: sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); delete_obj: @@ -375,6 +832,13 @@ delete_obj: static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) { + struct thpsize *thpsize, *tmp; + + list_for_each_entry_safe(thpsize, tmp, &thpsize_list, node) { + list_del(&thpsize->node); + kobject_put(&thpsize->kobj); + } + sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); kobject_put(hugepage_kobj); @@ -390,25 +854,66 @@ static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) } #endif /* CONFIG_SYSFS */ +static int __init thp_shrinker_init(void) +{ + deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE | + SHRINKER_MEMCG_AWARE | + SHRINKER_NONSLAB, + "thp-deferred_split"); + if (!deferred_split_shrinker) + return -ENOMEM; + + deferred_split_shrinker->count_objects = deferred_split_count; + deferred_split_shrinker->scan_objects = deferred_split_scan; + shrinker_register(deferred_split_shrinker); + + if (IS_ENABLED(CONFIG_PERSISTENT_HUGE_ZERO_FOLIO)) { + /* + * Bump the reference of the huge_zero_folio and do not + * initialize the shrinker. + * + * huge_zero_folio will always be NULL on failure. We assume + * that get_huge_zero_folio() will most likely not fail as + * thp_shrinker_init() is invoked early on during boot. + */ + if (!get_huge_zero_folio()) + pr_warn("Allocating persistent huge zero folio failed\n"); + return 0; + } + + huge_zero_folio_shrinker = shrinker_alloc(0, "thp-zero"); + if (!huge_zero_folio_shrinker) { + shrinker_free(deferred_split_shrinker); + return -ENOMEM; + } + + huge_zero_folio_shrinker->count_objects = shrink_huge_zero_folio_count; + huge_zero_folio_shrinker->scan_objects = shrink_huge_zero_folio_scan; + shrinker_register(huge_zero_folio_shrinker); + + return 0; +} + +static void __init thp_shrinker_exit(void) +{ + shrinker_free(huge_zero_folio_shrinker); + shrinker_free(deferred_split_shrinker); +} + static int __init hugepage_init(void) { int err; struct kobject *hugepage_kobj; if (!has_transparent_hugepage()) { - transparent_hugepage_flags = 0; + transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED; return -EINVAL; } /* * hugepages can't be allocated by the buddy allocator */ - MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); - /* - * we use page->mapping and page->index in second tail page - * as list_head: assuming THP order >= 2 - */ - MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); + MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER > MAX_PAGE_ORDER); err = hugepage_init_sysfs(&hugepage_kobj); if (err) @@ -418,19 +923,16 @@ static int __init hugepage_init(void) if (err) goto err_slab; - err = register_shrinker(&huge_zero_page_shrinker); - if (err) - goto err_hzp_shrinker; - err = register_shrinker(&deferred_split_shrinker); + err = thp_shrinker_init(); if (err) - goto err_split_shrinker; + goto err_shrinker; /* * By default disable transparent hugepages on smaller systems, * where the extra memory used could hurt more than TLB overhead * is likely to save. The admin can still enable it through /sys. */ - if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { + if (totalram_pages() < MB_TO_PAGES(512)) { transparent_hugepage_flags = 0; return 0; } @@ -441,10 +943,8 @@ static int __init hugepage_init(void) return 0; err_khugepaged: - unregister_shrinker(&deferred_split_shrinker); -err_split_shrinker: - unregister_shrinker(&huge_zero_page_shrinker); -err_hzp_shrinker: + thp_shrinker_exit(); +err_shrinker: khugepaged_destroy(); err_slab: hugepage_exit_sysfs(hugepage_kobj); @@ -484,37 +984,216 @@ out: } __setup("transparent_hugepage=", setup_transparent_hugepage); +static char str_dup[PAGE_SIZE] __initdata; +static int __init setup_thp_anon(char *str) +{ + char *token, *range, *policy, *subtoken; + unsigned long always, inherit, madvise; + char *start_size, *end_size; + int start, end, nr; + char *p; + + if (!str || strlen(str) + 1 > PAGE_SIZE) + goto err; + strscpy(str_dup, str); + + always = huge_anon_orders_always; + madvise = huge_anon_orders_madvise; + inherit = huge_anon_orders_inherit; + p = str_dup; + while ((token = strsep(&p, ";")) != NULL) { + range = strsep(&token, ":"); + policy = token; + + if (!policy) + goto err; + + while ((subtoken = strsep(&range, ",")) != NULL) { + if (strchr(subtoken, '-')) { + start_size = strsep(&subtoken, "-"); + end_size = subtoken; + + start = get_order_from_str(start_size, THP_ORDERS_ALL_ANON); + end = get_order_from_str(end_size, THP_ORDERS_ALL_ANON); + } else { + start_size = end_size = subtoken; + start = end = get_order_from_str(subtoken, + THP_ORDERS_ALL_ANON); + } + + if (start == -EINVAL) { + pr_err("invalid size %s in thp_anon boot parameter\n", start_size); + goto err; + } + + if (end == -EINVAL) { + pr_err("invalid size %s in thp_anon boot parameter\n", end_size); + goto err; + } + + if (start < 0 || end < 0 || start > end) + goto err; + + nr = end - start + 1; + if (!strcmp(policy, "always")) { + bitmap_set(&always, start, nr); + bitmap_clear(&inherit, start, nr); + bitmap_clear(&madvise, start, nr); + } else if (!strcmp(policy, "madvise")) { + bitmap_set(&madvise, start, nr); + bitmap_clear(&inherit, start, nr); + bitmap_clear(&always, start, nr); + } else if (!strcmp(policy, "inherit")) { + bitmap_set(&inherit, start, nr); + bitmap_clear(&madvise, start, nr); + bitmap_clear(&always, start, nr); + } else if (!strcmp(policy, "never")) { + bitmap_clear(&inherit, start, nr); + bitmap_clear(&madvise, start, nr); + bitmap_clear(&always, start, nr); + } else { + pr_err("invalid policy %s in thp_anon boot parameter\n", policy); + goto err; + } + } + } + + huge_anon_orders_always = always; + huge_anon_orders_madvise = madvise; + huge_anon_orders_inherit = inherit; + anon_orders_configured = true; + return 1; + +err: + pr_warn("thp_anon=%s: error parsing string, ignoring setting\n", str); + return 0; +} +__setup("thp_anon=", setup_thp_anon); + pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) { if (likely(vma->vm_flags & VM_WRITE)) - pmd = pmd_mkwrite(pmd); + pmd = pmd_mkwrite(pmd, vma); return pmd; } -static inline struct list_head *page_deferred_list(struct page *page) +static struct deferred_split *split_queue_node(int nid) +{ + struct pglist_data *pgdata = NODE_DATA(nid); + + return &pgdata->deferred_split_queue; +} + +#ifdef CONFIG_MEMCG +static inline +struct mem_cgroup *folio_split_queue_memcg(struct folio *folio, + struct deferred_split *queue) { - /* ->lru in the tail pages is occupied by compound_head. */ - return &page[2].deferred_list; + if (mem_cgroup_disabled()) + return NULL; + if (split_queue_node(folio_nid(folio)) == queue) + return NULL; + return container_of(queue, struct mem_cgroup, deferred_split_queue); } -void prep_transhuge_page(struct page *page) +static struct deferred_split *memcg_split_queue(int nid, struct mem_cgroup *memcg) +{ + return memcg ? &memcg->deferred_split_queue : split_queue_node(nid); +} +#else +static inline +struct mem_cgroup *folio_split_queue_memcg(struct folio *folio, + struct deferred_split *queue) { + return NULL; +} + +static struct deferred_split *memcg_split_queue(int nid, struct mem_cgroup *memcg) +{ + return split_queue_node(nid); +} +#endif + +static struct deferred_split *split_queue_lock(int nid, struct mem_cgroup *memcg) +{ + struct deferred_split *queue; + +retry: + queue = memcg_split_queue(nid, memcg); + spin_lock(&queue->split_queue_lock); /* - * we use page->mapping and page->indexlru in second tail page - * as list_head: assuming THP order >= 2 + * There is a period between setting memcg to dying and reparenting + * deferred split queue, and during this period the THPs in the deferred + * split queue will be hidden from the shrinker side. */ + if (unlikely(memcg_is_dying(memcg))) { + spin_unlock(&queue->split_queue_lock); + memcg = parent_mem_cgroup(memcg); + goto retry; + } - INIT_LIST_HEAD(page_deferred_list(page)); - set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); + return queue; } -unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len, - loff_t off, unsigned long flags, unsigned long size) +static struct deferred_split * +split_queue_lock_irqsave(int nid, struct mem_cgroup *memcg, unsigned long *flags) +{ + struct deferred_split *queue; + +retry: + queue = memcg_split_queue(nid, memcg); + spin_lock_irqsave(&queue->split_queue_lock, *flags); + if (unlikely(memcg_is_dying(memcg))) { + spin_unlock_irqrestore(&queue->split_queue_lock, *flags); + memcg = parent_mem_cgroup(memcg); + goto retry; + } + + return queue; +} + +static struct deferred_split *folio_split_queue_lock(struct folio *folio) +{ + return split_queue_lock(folio_nid(folio), folio_memcg(folio)); +} + +static struct deferred_split * +folio_split_queue_lock_irqsave(struct folio *folio, unsigned long *flags) +{ + return split_queue_lock_irqsave(folio_nid(folio), folio_memcg(folio), flags); +} + +static inline void split_queue_unlock(struct deferred_split *queue) +{ + spin_unlock(&queue->split_queue_lock); +} + +static inline void split_queue_unlock_irqrestore(struct deferred_split *queue, + unsigned long flags) +{ + spin_unlock_irqrestore(&queue->split_queue_lock, flags); +} + +static inline bool is_transparent_hugepage(const struct folio *folio) +{ + if (!folio_test_large(folio)) + return false; + + return is_huge_zero_folio(folio) || + folio_test_large_rmappable(folio); +} + +static unsigned long __thp_get_unmapped_area(struct file *filp, + unsigned long addr, unsigned long len, + loff_t off, unsigned long flags, unsigned long size, + vm_flags_t vm_flags) { - unsigned long addr; loff_t off_end = off + len; loff_t off_align = round_up(off, size); - unsigned long len_pad; + unsigned long len_pad, ret, off_sub; + + if (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()) + return 0; if (off_end <= off_align || (off_end - off_align) < size) return 0; @@ -523,50 +1202,132 @@ unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len, if (len_pad < len || (off + len_pad) < off) return 0; - addr = current->mm->get_unmapped_area(filp, 0, len_pad, - off >> PAGE_SHIFT, flags); - if (IS_ERR_VALUE(addr)) + ret = mm_get_unmapped_area_vmflags(filp, addr, len_pad, + off >> PAGE_SHIFT, flags, vm_flags); + + /* + * The failure might be due to length padding. The caller will retry + * without the padding. + */ + if (IS_ERR_VALUE(ret)) return 0; - addr += (off - addr) & (size - 1); - return addr; + /* + * Do not try to align to THP boundary if allocation at the address + * hint succeeds. + */ + if (ret == addr) + return addr; + + off_sub = (off - ret) & (size - 1); + + if (mm_flags_test(MMF_TOPDOWN, current->mm) && !off_sub) + return ret + size; + + ret += off_sub; + return ret; } -unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, - unsigned long len, unsigned long pgoff, unsigned long flags) +unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags, + vm_flags_t vm_flags) { + unsigned long ret; loff_t off = (loff_t)pgoff << PAGE_SHIFT; - if (addr) - goto out; - if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) - goto out; + ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE, vm_flags); + if (ret) + return ret; - addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE); - if (addr) - return addr; + return mm_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags, + vm_flags); +} - out: - return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); +unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags) +{ + return thp_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags, 0); } EXPORT_SYMBOL_GPL(thp_get_unmapped_area); -static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, - struct page *page, gfp_t gfp) +static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma, + unsigned long addr) { + gfp_t gfp = vma_thp_gfp_mask(vma); + const int order = HPAGE_PMD_ORDER; + struct folio *folio; + + folio = vma_alloc_folio(gfp, order, vma, addr & HPAGE_PMD_MASK); + + if (unlikely(!folio)) { + count_vm_event(THP_FAULT_FALLBACK); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); + return NULL; + } + + VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); + if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) { + folio_put(folio); + count_vm_event(THP_FAULT_FALLBACK); + count_vm_event(THP_FAULT_FALLBACK_CHARGE); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); + return NULL; + } + folio_throttle_swaprate(folio, gfp); + + /* + * When a folio is not zeroed during allocation (__GFP_ZERO not used) + * or user folios require special handling, folio_zero_user() is used to + * make sure that the page corresponding to the faulting address will be + * hot in the cache after zeroing. + */ + if (user_alloc_needs_zeroing()) + folio_zero_user(folio, addr); + /* + * The memory barrier inside __folio_mark_uptodate makes sure that + * folio_zero_user writes become visible before the set_pmd_at() + * write. + */ + __folio_mark_uptodate(folio); + return folio; +} + +void map_anon_folio_pmd_nopf(struct folio *folio, pmd_t *pmd, + struct vm_area_struct *vma, unsigned long haddr) +{ + pmd_t entry; + + entry = folio_mk_pmd(folio, vma->vm_page_prot); + entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE); + folio_add_lru_vma(folio, vma); + set_pmd_at(vma->vm_mm, haddr, pmd, entry); + update_mmu_cache_pmd(vma, haddr, pmd); + deferred_split_folio(folio, false); +} + +static void map_anon_folio_pmd_pf(struct folio *folio, pmd_t *pmd, + struct vm_area_struct *vma, unsigned long haddr) +{ + map_anon_folio_pmd_nopf(folio, pmd, vma, haddr); + add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); + count_vm_event(THP_FAULT_ALLOC); + count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC); + count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); +} + +static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf) +{ + unsigned long haddr = vmf->address & HPAGE_PMD_MASK; struct vm_area_struct *vma = vmf->vma; - struct mem_cgroup *memcg; + struct folio *folio; pgtable_t pgtable; - unsigned long haddr = vmf->address & HPAGE_PMD_MASK; vm_fault_t ret = 0; - VM_BUG_ON_PAGE(!PageCompound(page), page); - - if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) { - put_page(page); - count_vm_event(THP_FAULT_FALLBACK); + folio = vma_alloc_anon_folio_pmd(vma, vmf->address); + if (unlikely(!folio)) return VM_FAULT_FALLBACK; - } pgtable = pte_alloc_one(vma->vm_mm); if (unlikely(!pgtable)) { @@ -574,48 +1335,27 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, goto release; } - clear_huge_page(page, vmf->address, HPAGE_PMD_NR); - /* - * The memory barrier inside __SetPageUptodate makes sure that - * clear_huge_page writes become visible before the set_pmd_at() - * write. - */ - __SetPageUptodate(page); - vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); if (unlikely(!pmd_none(*vmf->pmd))) { goto unlock_release; } else { - pmd_t entry; - ret = check_stable_address_space(vma->vm_mm); if (ret) goto unlock_release; /* Deliver the page fault to userland */ if (userfaultfd_missing(vma)) { - vm_fault_t ret2; - spin_unlock(vmf->ptl); - mem_cgroup_cancel_charge(page, memcg, true); - put_page(page); + folio_put(folio); pte_free(vma->vm_mm, pgtable); - ret2 = handle_userfault(vmf, VM_UFFD_MISSING); - VM_BUG_ON(ret2 & VM_FAULT_FALLBACK); - return ret2; + ret = handle_userfault(vmf, VM_UFFD_MISSING); + VM_BUG_ON(ret & VM_FAULT_FALLBACK); + return ret; } - - entry = mk_huge_pmd(page, vma->vm_page_prot); - entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); - page_add_new_anon_rmap(page, vma, haddr, true); - mem_cgroup_commit_charge(page, memcg, false, true); - lru_cache_add_active_or_unevictable(page, vma); pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); - set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); - add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); + map_anon_folio_pmd_pf(folio, vmf->pmd, vma, haddr); mm_inc_nr_ptes(vma->vm_mm); spin_unlock(vmf->ptl); - count_vm_event(THP_FAULT_ALLOC); } return 0; @@ -624,12 +1364,49 @@ unlock_release: release: if (pgtable) pte_free(vma->vm_mm, pgtable); - mem_cgroup_cancel_charge(page, memcg, true); - put_page(page); + folio_put(folio); return ret; } +vm_fault_t do_huge_pmd_device_private(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + vm_fault_t ret = 0; + spinlock_t *ptl; + softleaf_t entry; + struct page *page; + struct folio *folio; + + if (vmf->flags & FAULT_FLAG_VMA_LOCK) { + vma_end_read(vma); + return VM_FAULT_RETRY; + } + + ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) { + spin_unlock(ptl); + return 0; + } + + entry = softleaf_from_pmd(vmf->orig_pmd); + page = softleaf_to_page(entry); + folio = page_folio(page); + vmf->page = page; + vmf->pte = NULL; + if (folio_trylock(folio)) { + folio_get(folio); + spin_unlock(ptl); + ret = page_pgmap(page)->ops->migrate_to_ram(vmf); + folio_unlock(folio); + folio_put(folio); + } else { + spin_unlock(ptl); + } + + return ret; +} + /* * always: directly stall for all thp allocations * defer: wake kswapd and fail if not immediately available @@ -639,9 +1416,9 @@ release: * available * never: never stall for any thp allocation */ -static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma) +gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) { - const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE); + const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); /* Always do synchronous compaction */ if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) @@ -666,96 +1443,133 @@ static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma) } /* Caller must hold page table lock. */ -static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, +static void set_huge_zero_folio(pgtable_t pgtable, struct mm_struct *mm, struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, - struct page *zero_page) + struct folio *zero_folio) { pmd_t entry; - if (!pmd_none(*pmd)) - return false; - entry = mk_pmd(zero_page, vma->vm_page_prot); - entry = pmd_mkhuge(entry); - if (pgtable) - pgtable_trans_huge_deposit(mm, pmd, pgtable); + entry = folio_mk_pmd(zero_folio, vma->vm_page_prot); + entry = pmd_mkspecial(entry); + pgtable_trans_huge_deposit(mm, pmd, pgtable); set_pmd_at(mm, haddr, pmd, entry); mm_inc_nr_ptes(mm); - return true; } vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; - gfp_t gfp; - struct page *page; unsigned long haddr = vmf->address & HPAGE_PMD_MASK; + vm_fault_t ret; - if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) + if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER)) return VM_FAULT_FALLBACK; - if (unlikely(anon_vma_prepare(vma))) - return VM_FAULT_OOM; - if (unlikely(khugepaged_enter(vma, vma->vm_flags))) - return VM_FAULT_OOM; + ret = vmf_anon_prepare(vmf); + if (ret) + return ret; + khugepaged_enter_vma(vma, vma->vm_flags); + if (!(vmf->flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(vma->vm_mm) && transparent_hugepage_use_zero_page()) { pgtable_t pgtable; - struct page *zero_page; - bool set; + struct folio *zero_folio; vm_fault_t ret; + pgtable = pte_alloc_one(vma->vm_mm); if (unlikely(!pgtable)) return VM_FAULT_OOM; - zero_page = mm_get_huge_zero_page(vma->vm_mm); - if (unlikely(!zero_page)) { + zero_folio = mm_get_huge_zero_folio(vma->vm_mm); + if (unlikely(!zero_folio)) { pte_free(vma->vm_mm, pgtable); count_vm_event(THP_FAULT_FALLBACK); return VM_FAULT_FALLBACK; } vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); ret = 0; - set = false; if (pmd_none(*vmf->pmd)) { ret = check_stable_address_space(vma->vm_mm); if (ret) { spin_unlock(vmf->ptl); + pte_free(vma->vm_mm, pgtable); } else if (userfaultfd_missing(vma)) { spin_unlock(vmf->ptl); + pte_free(vma->vm_mm, pgtable); ret = handle_userfault(vmf, VM_UFFD_MISSING); VM_BUG_ON(ret & VM_FAULT_FALLBACK); } else { - set_huge_zero_page(pgtable, vma->vm_mm, vma, - haddr, vmf->pmd, zero_page); + set_huge_zero_folio(pgtable, vma->vm_mm, vma, + haddr, vmf->pmd, zero_folio); + update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); spin_unlock(vmf->ptl); - set = true; } - } else + } else { spin_unlock(vmf->ptl); - if (!set) pte_free(vma->vm_mm, pgtable); + } return ret; } - gfp = alloc_hugepage_direct_gfpmask(vma); - page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); - if (unlikely(!page)) { - count_vm_event(THP_FAULT_FALLBACK); - return VM_FAULT_FALLBACK; - } - prep_transhuge_page(page); - return __do_huge_pmd_anonymous_page(vmf, page, gfp); + + return __do_huge_pmd_anonymous_page(vmf); } -static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, - pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, - pgtable_t pgtable) +struct folio_or_pfn { + union { + struct folio *folio; + unsigned long pfn; + }; + bool is_folio; +}; + +static vm_fault_t insert_pmd(struct vm_area_struct *vma, unsigned long addr, + pmd_t *pmd, struct folio_or_pfn fop, pgprot_t prot, + bool write) { struct mm_struct *mm = vma->vm_mm; - pmd_t entry; + pgtable_t pgtable = NULL; spinlock_t *ptl; + pmd_t entry; + + if (addr < vma->vm_start || addr >= vma->vm_end) + return VM_FAULT_SIGBUS; + + if (arch_needs_pgtable_deposit()) { + pgtable = pte_alloc_one(vma->vm_mm); + if (!pgtable) + return VM_FAULT_OOM; + } ptl = pmd_lock(mm, pmd); - entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); - if (pfn_t_devmap(pfn)) - entry = pmd_mkdevmap(entry); + if (!pmd_none(*pmd)) { + const unsigned long pfn = fop.is_folio ? folio_pfn(fop.folio) : + fop.pfn; + + if (write) { + if (pmd_pfn(*pmd) != pfn) { + WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); + goto out_unlock; + } + entry = pmd_mkyoung(*pmd); + entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) + update_mmu_cache_pmd(vma, addr, pmd); + } + goto out_unlock; + } + + if (fop.is_folio) { + entry = folio_mk_pmd(fop.folio, vma->vm_page_prot); + + if (is_huge_zero_folio(fop.folio)) { + entry = pmd_mkspecial(entry); + } else { + folio_get(fop.folio); + folio_add_file_rmap_pmd(fop.folio, &fop.folio->page, vma); + add_mm_counter(mm, mm_counter_file(fop.folio), HPAGE_PMD_NR); + } + } else { + entry = pmd_mkhuge(pfn_pmd(fop.pfn, prot)); + entry = pmd_mkspecial(entry); + } if (write) { entry = pmd_mkyoung(pmd_mkdirty(entry)); entry = maybe_pmd_mkwrite(entry, vma); @@ -764,44 +1578,71 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, if (pgtable) { pgtable_trans_huge_deposit(mm, pmd, pgtable); mm_inc_nr_ptes(mm); + pgtable = NULL; } set_pmd_at(mm, addr, pmd, entry); update_mmu_cache_pmd(vma, addr, pmd); + +out_unlock: spin_unlock(ptl); + if (pgtable) + pte_free(mm, pgtable); + return VM_FAULT_NOPAGE; } -vm_fault_t vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, - pmd_t *pmd, pfn_t pfn, bool write) +/** + * vmf_insert_pfn_pmd - insert a pmd size pfn + * @vmf: Structure describing the fault + * @pfn: pfn to insert + * @write: whether it's a write fault + * + * Insert a pmd size pfn. See vmf_insert_pfn() for additional info. + * + * Return: vm_fault_t value. + */ +vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, unsigned long pfn, + bool write) { + unsigned long addr = vmf->address & PMD_MASK; + struct vm_area_struct *vma = vmf->vma; pgprot_t pgprot = vma->vm_page_prot; - pgtable_t pgtable = NULL; + struct folio_or_pfn fop = { + .pfn = pfn, + }; + /* * If we had pmd_special, we could avoid all these restrictions, * but we need to be consistent with PTEs and architectures that * can't support a 'special' bit. */ - BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && - !pfn_t_devmap(pfn)); + BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == (VM_PFNMAP|VM_MIXEDMAP)); BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); - if (addr < vma->vm_start || addr >= vma->vm_end) - return VM_FAULT_SIGBUS; + pfnmap_setup_cachemode_pfn(pfn, &pgprot); - if (arch_needs_pgtable_deposit()) { - pgtable = pte_alloc_one(vma->vm_mm); - if (!pgtable) - return VM_FAULT_OOM; - } + return insert_pmd(vma, addr, vmf->pmd, fop, pgprot, write); +} +EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); - track_pfn_insert(vma, &pgprot, pfn); +vm_fault_t vmf_insert_folio_pmd(struct vm_fault *vmf, struct folio *folio, + bool write) +{ + struct vm_area_struct *vma = vmf->vma; + unsigned long addr = vmf->address & PMD_MASK; + struct folio_or_pfn fop = { + .folio = folio, + .is_folio = true, + }; - insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable); - return VM_FAULT_NOPAGE; + if (WARN_ON_ONCE(folio_order(folio) != PMD_ORDER)) + return VM_FAULT_SIGBUS; + + return insert_pmd(vma, addr, vmf->pmd, fop, vma->vm_page_prot, write); } -EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); +EXPORT_SYMBOL_GPL(vmf_insert_folio_pmd); #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) @@ -811,120 +1652,229 @@ static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) return pud; } -static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, - pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) +static vm_fault_t insert_pud(struct vm_area_struct *vma, unsigned long addr, + pud_t *pud, struct folio_or_pfn fop, pgprot_t prot, bool write) { struct mm_struct *mm = vma->vm_mm; - pud_t entry; spinlock_t *ptl; + pud_t entry; + + if (addr < vma->vm_start || addr >= vma->vm_end) + return VM_FAULT_SIGBUS; ptl = pud_lock(mm, pud); - entry = pud_mkhuge(pfn_t_pud(pfn, prot)); - if (pfn_t_devmap(pfn)) - entry = pud_mkdevmap(entry); + if (!pud_none(*pud)) { + const unsigned long pfn = fop.is_folio ? folio_pfn(fop.folio) : + fop.pfn; + + if (write) { + if (WARN_ON_ONCE(pud_pfn(*pud) != pfn)) + goto out_unlock; + entry = pud_mkyoung(*pud); + entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); + if (pudp_set_access_flags(vma, addr, pud, entry, 1)) + update_mmu_cache_pud(vma, addr, pud); + } + goto out_unlock; + } + + if (fop.is_folio) { + entry = folio_mk_pud(fop.folio, vma->vm_page_prot); + + folio_get(fop.folio); + folio_add_file_rmap_pud(fop.folio, &fop.folio->page, vma); + add_mm_counter(mm, mm_counter_file(fop.folio), HPAGE_PUD_NR); + } else { + entry = pud_mkhuge(pfn_pud(fop.pfn, prot)); + entry = pud_mkspecial(entry); + } if (write) { entry = pud_mkyoung(pud_mkdirty(entry)); entry = maybe_pud_mkwrite(entry, vma); } set_pud_at(mm, addr, pud, entry); update_mmu_cache_pud(vma, addr, pud); +out_unlock: spin_unlock(ptl); + return VM_FAULT_NOPAGE; } -vm_fault_t vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, - pud_t *pud, pfn_t pfn, bool write) +/** + * vmf_insert_pfn_pud - insert a pud size pfn + * @vmf: Structure describing the fault + * @pfn: pfn to insert + * @write: whether it's a write fault + * + * Insert a pud size pfn. See vmf_insert_pfn() for additional info. + * + * Return: vm_fault_t value. + */ +vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, unsigned long pfn, + bool write) { + unsigned long addr = vmf->address & PUD_MASK; + struct vm_area_struct *vma = vmf->vma; pgprot_t pgprot = vma->vm_page_prot; + struct folio_or_pfn fop = { + .pfn = pfn, + }; + /* * If we had pud_special, we could avoid all these restrictions, * but we need to be consistent with PTEs and architectures that * can't support a 'special' bit. */ - BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && - !pfn_t_devmap(pfn)); + BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == (VM_PFNMAP|VM_MIXEDMAP)); BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); - if (addr < vma->vm_start || addr >= vma->vm_end) - return VM_FAULT_SIGBUS; - - track_pfn_insert(vma, &pgprot, pfn); + pfnmap_setup_cachemode_pfn(pfn, &pgprot); - insert_pfn_pud(vma, addr, pud, pfn, pgprot, write); - return VM_FAULT_NOPAGE; + return insert_pud(vma, addr, vmf->pud, fop, pgprot, write); } EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); -#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ -static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, - pmd_t *pmd, int flags) +/** + * vmf_insert_folio_pud - insert a pud size folio mapped by a pud entry + * @vmf: Structure describing the fault + * @folio: folio to insert + * @write: whether it's a write fault + * + * Return: vm_fault_t value. + */ +vm_fault_t vmf_insert_folio_pud(struct vm_fault *vmf, struct folio *folio, + bool write) { - pmd_t _pmd; + struct vm_area_struct *vma = vmf->vma; + unsigned long addr = vmf->address & PUD_MASK; + struct folio_or_pfn fop = { + .folio = folio, + .is_folio = true, + }; - _pmd = pmd_mkyoung(*pmd); - if (flags & FOLL_WRITE) - _pmd = pmd_mkdirty(_pmd); - if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, - pmd, _pmd, flags & FOLL_WRITE)) - update_mmu_cache_pmd(vma, addr, pmd); + if (WARN_ON_ONCE(folio_order(folio) != PUD_ORDER)) + return VM_FAULT_SIGBUS; + + return insert_pud(vma, addr, vmf->pud, fop, vma->vm_page_prot, write); } +EXPORT_SYMBOL_GPL(vmf_insert_folio_pud); +#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ -struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, - pmd_t *pmd, int flags, struct dev_pagemap **pgmap) +/** + * touch_pmd - Mark page table pmd entry as accessed and dirty (for write) + * @vma: The VMA covering @addr + * @addr: The virtual address + * @pmd: pmd pointer into the page table mapping @addr + * @write: Whether it's a write access + * + * Return: whether the pmd entry is changed + */ +bool touch_pmd(struct vm_area_struct *vma, unsigned long addr, + pmd_t *pmd, bool write) { - unsigned long pfn = pmd_pfn(*pmd); - struct mm_struct *mm = vma->vm_mm; - struct page *page; - - assert_spin_locked(pmd_lockptr(mm, pmd)); + pmd_t entry; - /* - * When we COW a devmap PMD entry, we split it into PTEs, so we should - * not be in this function with `flags & FOLL_COW` set. - */ - WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); + entry = pmd_mkyoung(*pmd); + if (write) + entry = pmd_mkdirty(entry); + if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, + pmd, entry, write)) { + update_mmu_cache_pmd(vma, addr, pmd); + return true; + } - if (flags & FOLL_WRITE && !pmd_write(*pmd)) - return NULL; + return false; +} - if (pmd_present(*pmd) && pmd_devmap(*pmd)) - /* pass */; - else - return NULL; +static void copy_huge_non_present_pmd( + struct mm_struct *dst_mm, struct mm_struct *src_mm, + pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, + struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, + pmd_t pmd, pgtable_t pgtable) +{ + softleaf_t entry = softleaf_from_pmd(pmd); + struct folio *src_folio; + + VM_WARN_ON_ONCE(!pmd_is_valid_softleaf(pmd)); + + if (softleaf_is_migration_write(entry) || + softleaf_is_migration_read_exclusive(entry)) { + entry = make_readable_migration_entry(swp_offset(entry)); + pmd = swp_entry_to_pmd(entry); + if (pmd_swp_soft_dirty(*src_pmd)) + pmd = pmd_swp_mksoft_dirty(pmd); + if (pmd_swp_uffd_wp(*src_pmd)) + pmd = pmd_swp_mkuffd_wp(pmd); + set_pmd_at(src_mm, addr, src_pmd, pmd); + } else if (softleaf_is_device_private(entry)) { + /* + * For device private entries, since there are no + * read exclusive entries, writable = !readable + */ + if (softleaf_is_device_private_write(entry)) { + entry = make_readable_device_private_entry(swp_offset(entry)); + pmd = swp_entry_to_pmd(entry); - if (flags & FOLL_TOUCH) - touch_pmd(vma, addr, pmd, flags); + if (pmd_swp_soft_dirty(*src_pmd)) + pmd = pmd_swp_mksoft_dirty(pmd); + if (pmd_swp_uffd_wp(*src_pmd)) + pmd = pmd_swp_mkuffd_wp(pmd); + set_pmd_at(src_mm, addr, src_pmd, pmd); + } - /* - * device mapped pages can only be returned if the - * caller will manage the page reference count. - */ - if (!(flags & FOLL_GET)) - return ERR_PTR(-EEXIST); + src_folio = softleaf_to_folio(entry); + VM_WARN_ON(!folio_test_large(src_folio)); - pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; - *pgmap = get_dev_pagemap(pfn, *pgmap); - if (!*pgmap) - return ERR_PTR(-EFAULT); - page = pfn_to_page(pfn); - get_page(page); + folio_get(src_folio); + /* + * folio_try_dup_anon_rmap_pmd does not fail for + * device private entries. + */ + folio_try_dup_anon_rmap_pmd(src_folio, &src_folio->page, + dst_vma, src_vma); + } - return page; + add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); + mm_inc_nr_ptes(dst_mm); + pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); + if (!userfaultfd_wp(dst_vma)) + pmd = pmd_swp_clear_uffd_wp(pmd); + set_pmd_at(dst_mm, addr, dst_pmd, pmd); } int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, - struct vm_area_struct *vma) + struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) { spinlock_t *dst_ptl, *src_ptl; struct page *src_page; + struct folio *src_folio; pmd_t pmd; pgtable_t pgtable = NULL; int ret = -ENOMEM; + pmd = pmdp_get_lockless(src_pmd); + if (unlikely(pmd_present(pmd) && pmd_special(pmd) && + !is_huge_zero_pmd(pmd))) { + dst_ptl = pmd_lock(dst_mm, dst_pmd); + src_ptl = pmd_lockptr(src_mm, src_pmd); + spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); + /* + * No need to recheck the pmd, it can't change with write + * mmap lock held here. + * + * Meanwhile, making sure it's not a CoW VMA with writable + * mapping, otherwise it means either the anon page wrongly + * applied special bit, or we made the PRIVATE mapping be + * able to wrongly write to the backend MMIO. + */ + VM_WARN_ON_ONCE(is_cow_mapping(src_vma->vm_flags) && pmd_write(pmd)); + goto set_pmd; + } + /* Skip if can be re-fill on fault */ - if (!vma_is_anonymous(vma)) + if (!vma_is_anonymous(dst_vma)) return 0; pgtable = pte_alloc_one(dst_mm); @@ -938,26 +1888,13 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, ret = -EAGAIN; pmd = *src_pmd; -#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION - if (unlikely(is_swap_pmd(pmd))) { - swp_entry_t entry = pmd_to_swp_entry(pmd); - - VM_BUG_ON(!is_pmd_migration_entry(pmd)); - if (is_write_migration_entry(entry)) { - make_migration_entry_read(&entry); - pmd = swp_entry_to_pmd(entry); - if (pmd_swp_soft_dirty(*src_pmd)) - pmd = pmd_swp_mksoft_dirty(pmd); - set_pmd_at(src_mm, addr, src_pmd, pmd); - } - add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); - mm_inc_nr_ptes(dst_mm); - pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); - set_pmd_at(dst_mm, addr, dst_pmd, pmd); + if (unlikely(thp_migration_supported() && + pmd_is_valid_softleaf(pmd))) { + copy_huge_non_present_pmd(dst_mm, src_mm, dst_pmd, src_pmd, addr, + dst_vma, src_vma, pmd, pgtable); ret = 0; goto out_unlock; } -#endif if (unlikely(!pmd_trans_huge(pmd))) { pte_free(dst_mm, pgtable); @@ -969,29 +1906,39 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, * a page table. */ if (is_huge_zero_pmd(pmd)) { - struct page *zero_page; /* - * get_huge_zero_page() will never allocate a new page here, - * since we already have a zero page to copy. It just takes a - * reference. + * mm_get_huge_zero_folio() will never allocate a new + * folio here, since we already have a zero page to + * copy. It just takes a reference. */ - zero_page = mm_get_huge_zero_page(dst_mm); - set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, - zero_page); - ret = 0; - goto out_unlock; + mm_get_huge_zero_folio(dst_mm); + goto out_zero_page; } src_page = pmd_page(pmd); VM_BUG_ON_PAGE(!PageHead(src_page), src_page); - get_page(src_page); - page_dup_rmap(src_page, true); + src_folio = page_folio(src_page); + + folio_get(src_folio); + if (unlikely(folio_try_dup_anon_rmap_pmd(src_folio, src_page, dst_vma, src_vma))) { + /* Page maybe pinned: split and retry the fault on PTEs. */ + folio_put(src_folio); + pte_free(dst_mm, pgtable); + spin_unlock(src_ptl); + spin_unlock(dst_ptl); + __split_huge_pmd(src_vma, src_pmd, addr, false); + return -EAGAIN; + } add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); +out_zero_page: mm_inc_nr_ptes(dst_mm); pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); - pmdp_set_wrprotect(src_mm, addr, src_pmd); - pmd = pmd_mkold(pmd_wrprotect(pmd)); + if (!userfaultfd_wp(dst_vma)) + pmd = pmd_clear_uffd_wp(pmd); + pmd = pmd_wrprotect(pmd); +set_pmd: + pmd = pmd_mkold(pmd); set_pmd_at(dst_mm, addr, dst_pmd, pmd); ret = 0; @@ -1003,56 +1950,19 @@ out: } #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD -static void touch_pud(struct vm_area_struct *vma, unsigned long addr, - pud_t *pud, int flags) +void touch_pud(struct vm_area_struct *vma, unsigned long addr, + pud_t *pud, bool write) { pud_t _pud; _pud = pud_mkyoung(*pud); - if (flags & FOLL_WRITE) + if (write) _pud = pud_mkdirty(_pud); if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, - pud, _pud, flags & FOLL_WRITE)) + pud, _pud, write)) update_mmu_cache_pud(vma, addr, pud); } -struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, - pud_t *pud, int flags, struct dev_pagemap **pgmap) -{ - unsigned long pfn = pud_pfn(*pud); - struct mm_struct *mm = vma->vm_mm; - struct page *page; - - assert_spin_locked(pud_lockptr(mm, pud)); - - if (flags & FOLL_WRITE && !pud_write(*pud)) - return NULL; - - if (pud_present(*pud) && pud_devmap(*pud)) - /* pass */; - else - return NULL; - - if (flags & FOLL_TOUCH) - touch_pud(vma, addr, pud, flags); - - /* - * device mapped pages can only be returned if the - * caller will manage the page reference count. - */ - if (!(flags & FOLL_GET)) - return ERR_PTR(-EEXIST); - - pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; - *pgmap = get_dev_pagemap(pfn, *pgmap); - if (!*pgmap) - return ERR_PTR(-EFAULT); - page = pfn_to_page(pfn); - get_page(page); - - return page; -} - int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, pud_t *dst_pud, pud_t *src_pud, unsigned long addr, struct vm_area_struct *vma) @@ -1067,20 +1977,18 @@ int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, ret = -EAGAIN; pud = *src_pud; - if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) + if (unlikely(!pud_trans_huge(pud))) goto out_unlock; /* - * When page table lock is held, the huge zero pud should not be - * under splitting since we don't split the page itself, only pud to - * a page table. + * TODO: once we support anonymous pages, use + * folio_try_dup_anon_rmap_*() and split if duplicating fails. */ - if (is_huge_zero_pud(pud)) { - /* No huge zero pud yet */ + if (is_cow_mapping(vma->vm_flags) && pud_write(pud)) { + pudp_set_wrprotect(src_mm, addr, src_pud); + pud = pud_wrprotect(pud); } - - pudp_set_wrprotect(src_mm, addr, src_pud); - pud = pud_mkold(pud_wrprotect(pud)); + pud = pud_mkold(pud); set_pud_at(dst_mm, addr, dst_pud, pud); ret = 0; @@ -1092,536 +2000,258 @@ out_unlock: void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) { - pud_t entry; - unsigned long haddr; bool write = vmf->flags & FAULT_FLAG_WRITE; vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); if (unlikely(!pud_same(*vmf->pud, orig_pud))) goto unlock; - entry = pud_mkyoung(orig_pud); - if (write) - entry = pud_mkdirty(entry); - haddr = vmf->address & HPAGE_PUD_MASK; - if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) - update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); - + touch_pud(vmf->vma, vmf->address, vmf->pud, write); unlock: spin_unlock(vmf->ptl); } #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ -void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd) +bool huge_pmd_set_accessed(struct vm_fault *vmf) { - pmd_t entry; - unsigned long haddr; bool write = vmf->flags & FAULT_FLAG_WRITE; - vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); - if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) - goto unlock; - - entry = pmd_mkyoung(orig_pmd); - if (write) - entry = pmd_mkdirty(entry); - haddr = vmf->address & HPAGE_PMD_MASK; - if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) - update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); + if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) + return false; -unlock: - spin_unlock(vmf->ptl); + return touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); } -static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, - pmd_t orig_pmd, struct page *page) +static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf) { - struct vm_area_struct *vma = vmf->vma; unsigned long haddr = vmf->address & HPAGE_PMD_MASK; - struct mem_cgroup *memcg; - pgtable_t pgtable; - pmd_t _pmd; - int i; - vm_fault_t ret = 0; - struct page **pages; + struct vm_area_struct *vma = vmf->vma; struct mmu_notifier_range range; + struct folio *folio; + vm_fault_t ret = 0; - pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *), - GFP_KERNEL); - if (unlikely(!pages)) { - ret |= VM_FAULT_OOM; - goto out; - } - - for (i = 0; i < HPAGE_PMD_NR; i++) { - pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma, - vmf->address, page_to_nid(page)); - if (unlikely(!pages[i] || - mem_cgroup_try_charge_delay(pages[i], vma->vm_mm, - GFP_KERNEL, &memcg, false))) { - if (pages[i]) - put_page(pages[i]); - while (--i >= 0) { - memcg = (void *)page_private(pages[i]); - set_page_private(pages[i], 0); - mem_cgroup_cancel_charge(pages[i], memcg, - false); - put_page(pages[i]); - } - kfree(pages); - ret |= VM_FAULT_OOM; - goto out; - } - set_page_private(pages[i], (unsigned long)memcg); - } - - for (i = 0; i < HPAGE_PMD_NR; i++) { - copy_user_highpage(pages[i], page + i, - haddr + PAGE_SIZE * i, vma); - __SetPageUptodate(pages[i]); - cond_resched(); - } + folio = vma_alloc_anon_folio_pmd(vma, vmf->address); + if (unlikely(!folio)) + return VM_FAULT_FALLBACK; - mmu_notifier_range_init(&range, vma->vm_mm, haddr, + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, haddr, haddr + HPAGE_PMD_SIZE); mmu_notifier_invalidate_range_start(&range); - vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); - if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) - goto out_free_pages; - VM_BUG_ON_PAGE(!PageHead(page), page); - - /* - * Leave pmd empty until pte is filled note we must notify here as - * concurrent CPU thread might write to new page before the call to - * mmu_notifier_invalidate_range_end() happens which can lead to a - * device seeing memory write in different order than CPU. - * - * See Documentation/vm/mmu_notifier.rst - */ - pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); - - pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd); - pmd_populate(vma->vm_mm, &_pmd, pgtable); - - for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { - pte_t entry; - entry = mk_pte(pages[i], vma->vm_page_prot); - entry = maybe_mkwrite(pte_mkdirty(entry), vma); - memcg = (void *)page_private(pages[i]); - set_page_private(pages[i], 0); - page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false); - mem_cgroup_commit_charge(pages[i], memcg, false, false); - lru_cache_add_active_or_unevictable(pages[i], vma); - vmf->pte = pte_offset_map(&_pmd, haddr); - VM_BUG_ON(!pte_none(*vmf->pte)); - set_pte_at(vma->vm_mm, haddr, vmf->pte, entry); - pte_unmap(vmf->pte); - } - kfree(pages); - - smp_wmb(); /* make pte visible before pmd */ - pmd_populate(vma->vm_mm, vmf->pmd, pgtable); - page_remove_rmap(page, true); - spin_unlock(vmf->ptl); - - /* - * No need to double call mmu_notifier->invalidate_range() callback as - * the above pmdp_huge_clear_flush_notify() did already call it. - */ - mmu_notifier_invalidate_range_only_end(&range); - - ret |= VM_FAULT_WRITE; - put_page(page); - -out: - return ret; - -out_free_pages: + if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd))) + goto release; + ret = check_stable_address_space(vma->vm_mm); + if (ret) + goto release; + (void)pmdp_huge_clear_flush(vma, haddr, vmf->pmd); + map_anon_folio_pmd_pf(folio, vmf->pmd, vma, haddr); + goto unlock; +release: + folio_put(folio); +unlock: spin_unlock(vmf->ptl); mmu_notifier_invalidate_range_end(&range); - for (i = 0; i < HPAGE_PMD_NR; i++) { - memcg = (void *)page_private(pages[i]); - set_page_private(pages[i], 0); - mem_cgroup_cancel_charge(pages[i], memcg, false); - put_page(pages[i]); - } - kfree(pages); - goto out; + return ret; } -vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) +vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) { + const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; struct vm_area_struct *vma = vmf->vma; - struct page *page = NULL, *new_page; - struct mem_cgroup *memcg; + struct folio *folio; + struct page *page; unsigned long haddr = vmf->address & HPAGE_PMD_MASK; - struct mmu_notifier_range range; - gfp_t huge_gfp; /* for allocation and charge */ - vm_fault_t ret = 0; + pmd_t orig_pmd = vmf->orig_pmd; vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); VM_BUG_ON_VMA(!vma->anon_vma, vma); - if (is_huge_zero_pmd(orig_pmd)) - goto alloc; + + if (is_huge_zero_pmd(orig_pmd)) { + vm_fault_t ret = do_huge_zero_wp_pmd(vmf); + + if (!(ret & VM_FAULT_FALLBACK)) + return ret; + + /* Fallback to splitting PMD if THP cannot be allocated */ + goto fallback; + } + spin_lock(vmf->ptl); - if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) - goto out_unlock; + + if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { + spin_unlock(vmf->ptl); + return 0; + } page = pmd_page(orig_pmd); - VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); - /* - * We can only reuse the page if nobody else maps the huge page or it's - * part. - */ - if (!trylock_page(page)) { - get_page(page); + folio = page_folio(page); + VM_BUG_ON_PAGE(!PageHead(page), page); + + /* Early check when only holding the PT lock. */ + if (PageAnonExclusive(page)) + goto reuse; + + if (!folio_trylock(folio)) { + folio_get(folio); spin_unlock(vmf->ptl); - lock_page(page); + folio_lock(folio); spin_lock(vmf->ptl); if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { - unlock_page(page); - put_page(page); - goto out_unlock; - } - put_page(page); - } - if (reuse_swap_page(page, NULL)) { - pmd_t entry; - entry = pmd_mkyoung(orig_pmd); - entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); - if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) - update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); - ret |= VM_FAULT_WRITE; - unlock_page(page); - goto out_unlock; - } - unlock_page(page); - get_page(page); - spin_unlock(vmf->ptl); -alloc: - if (__transparent_hugepage_enabled(vma) && - !transparent_hugepage_debug_cow()) { - huge_gfp = alloc_hugepage_direct_gfpmask(vma); - new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); - } else - new_page = NULL; - - if (likely(new_page)) { - prep_transhuge_page(new_page); - } else { - if (!page) { - split_huge_pmd(vma, vmf->pmd, vmf->address); - ret |= VM_FAULT_FALLBACK; - } else { - ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page); - if (ret & VM_FAULT_OOM) { - split_huge_pmd(vma, vmf->pmd, vmf->address); - ret |= VM_FAULT_FALLBACK; - } - put_page(page); + spin_unlock(vmf->ptl); + folio_unlock(folio); + folio_put(folio); + return 0; } - count_vm_event(THP_FAULT_FALLBACK); - goto out; + folio_put(folio); } - if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm, - huge_gfp, &memcg, true))) { - put_page(new_page); - split_huge_pmd(vma, vmf->pmd, vmf->address); - if (page) - put_page(page); - ret |= VM_FAULT_FALLBACK; - count_vm_event(THP_FAULT_FALLBACK); - goto out; + /* Recheck after temporarily dropping the PT lock. */ + if (PageAnonExclusive(page)) { + folio_unlock(folio); + goto reuse; } - count_vm_event(THP_FAULT_ALLOC); - - if (!page) - clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR); - else - copy_user_huge_page(new_page, page, vmf->address, - vma, HPAGE_PMD_NR); - __SetPageUptodate(new_page); - - mmu_notifier_range_init(&range, vma->vm_mm, haddr, - haddr + HPAGE_PMD_SIZE); - mmu_notifier_invalidate_range_start(&range); - - spin_lock(vmf->ptl); - if (page) - put_page(page); - if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { - spin_unlock(vmf->ptl); - mem_cgroup_cancel_charge(new_page, memcg, true); - put_page(new_page); - goto out_mn; - } else { + /* + * See do_wp_page(): we can only reuse the folio exclusively if + * there are no additional references. Note that we always drain + * the LRU cache immediately after adding a THP. + */ + if (folio_ref_count(folio) > + 1 + folio_test_swapcache(folio) * folio_nr_pages(folio)) + goto unlock_fallback; + if (folio_test_swapcache(folio)) + folio_free_swap(folio); + if (folio_ref_count(folio) == 1) { pmd_t entry; - entry = mk_huge_pmd(new_page, vma->vm_page_prot); - entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); - pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); - page_add_new_anon_rmap(new_page, vma, haddr, true); - mem_cgroup_commit_charge(new_page, memcg, false, true); - lru_cache_add_active_or_unevictable(new_page, vma); - set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); - update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); - if (!page) { - add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); - } else { - VM_BUG_ON_PAGE(!PageHead(page), page); - page_remove_rmap(page, true); - put_page(page); + + folio_move_anon_rmap(folio, vma); + SetPageAnonExclusive(page); + folio_unlock(folio); +reuse: + if (unlikely(unshare)) { + spin_unlock(vmf->ptl); + return 0; } - ret |= VM_FAULT_WRITE; + entry = pmd_mkyoung(orig_pmd); + entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) + update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); + spin_unlock(vmf->ptl); + return 0; } - spin_unlock(vmf->ptl); -out_mn: - /* - * No need to double call mmu_notifier->invalidate_range() callback as - * the above pmdp_huge_clear_flush_notify() did already call it. - */ - mmu_notifier_invalidate_range_only_end(&range); -out: - return ret; -out_unlock: - spin_unlock(vmf->ptl); - return ret; -} -/* - * FOLL_FORCE can write to even unwritable pmd's, but only - * after we've gone through a COW cycle and they are dirty. - */ -static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) -{ - return pmd_write(pmd) || - ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); +unlock_fallback: + folio_unlock(folio); + spin_unlock(vmf->ptl); +fallback: + __split_huge_pmd(vma, vmf->pmd, vmf->address, false); + return VM_FAULT_FALLBACK; } -struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, - unsigned long addr, - pmd_t *pmd, - unsigned int flags) +static inline bool can_change_pmd_writable(struct vm_area_struct *vma, + unsigned long addr, pmd_t pmd) { - struct mm_struct *mm = vma->vm_mm; - struct page *page = NULL; - - assert_spin_locked(pmd_lockptr(mm, pmd)); + struct page *page; - if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) - goto out; + if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) + return false; - /* Avoid dumping huge zero page */ - if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) - return ERR_PTR(-EFAULT); + /* Don't touch entries that are not even readable (NUMA hinting). */ + if (pmd_protnone(pmd)) + return false; - /* Full NUMA hinting faults to serialise migration in fault paths */ - if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) - goto out; + /* Do we need write faults for softdirty tracking? */ + if (pmd_needs_soft_dirty_wp(vma, pmd)) + return false; - page = pmd_page(*pmd); - VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); - if (flags & FOLL_TOUCH) - touch_pmd(vma, addr, pmd, flags); - if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { - /* - * We don't mlock() pte-mapped THPs. This way we can avoid - * leaking mlocked pages into non-VM_LOCKED VMAs. - * - * For anon THP: - * - * In most cases the pmd is the only mapping of the page as we - * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for - * writable private mappings in populate_vma_page_range(). - * - * The only scenario when we have the page shared here is if we - * mlocking read-only mapping shared over fork(). We skip - * mlocking such pages. - * - * For file THP: - * - * We can expect PageDoubleMap() to be stable under page lock: - * for file pages we set it in page_add_file_rmap(), which - * requires page to be locked. - */ + /* Do we need write faults for uffd-wp tracking? */ + if (userfaultfd_huge_pmd_wp(vma, pmd)) + return false; - if (PageAnon(page) && compound_mapcount(page) != 1) - goto skip_mlock; - if (PageDoubleMap(page) || !page->mapping) - goto skip_mlock; - if (!trylock_page(page)) - goto skip_mlock; - lru_add_drain(); - if (page->mapping && !PageDoubleMap(page)) - mlock_vma_page(page); - unlock_page(page); - } -skip_mlock: - page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; - VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); - if (flags & FOLL_GET) - get_page(page); + if (!(vma->vm_flags & VM_SHARED)) { + /* See can_change_pte_writable(). */ + page = vm_normal_page_pmd(vma, addr, pmd); + return page && PageAnon(page) && PageAnonExclusive(page); + } -out: - return page; + /* See can_change_pte_writable(). */ + return pmd_dirty(pmd); } /* NUMA hinting page fault entry point for trans huge pmds */ -vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) +vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; - struct anon_vma *anon_vma = NULL; - struct page *page; + struct folio *folio; unsigned long haddr = vmf->address & HPAGE_PMD_MASK; - int page_nid = -1, this_nid = numa_node_id(); - int target_nid, last_cpupid = -1; - bool page_locked; - bool migrated = false; - bool was_writable; + int nid = NUMA_NO_NODE; + int target_nid, last_cpupid; + pmd_t pmd, old_pmd; + bool writable = false; int flags = 0; vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); - if (unlikely(!pmd_same(pmd, *vmf->pmd))) - goto out_unlock; + old_pmd = pmdp_get(vmf->pmd); - /* - * If there are potential migrations, wait for completion and retry - * without disrupting NUMA hinting information. Do not relock and - * check_same as the page may no longer be mapped. - */ - if (unlikely(pmd_trans_migrating(*vmf->pmd))) { - page = pmd_page(*vmf->pmd); - if (!get_page_unless_zero(page)) - goto out_unlock; + if (unlikely(!pmd_same(old_pmd, vmf->orig_pmd))) { spin_unlock(vmf->ptl); - put_and_wait_on_page_locked(page); - goto out; - } - - page = pmd_page(pmd); - BUG_ON(is_huge_zero_page(page)); - page_nid = page_to_nid(page); - last_cpupid = page_cpupid_last(page); - count_vm_numa_event(NUMA_HINT_FAULTS); - if (page_nid == this_nid) { - count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); - flags |= TNF_FAULT_LOCAL; + return 0; } - /* See similar comment in do_numa_page for explanation */ - if (!pmd_savedwrite(pmd)) - flags |= TNF_NO_GROUP; + pmd = pmd_modify(old_pmd, vma->vm_page_prot); /* - * Acquire the page lock to serialise THP migrations but avoid dropping - * page_table_lock if at all possible + * Detect now whether the PMD could be writable; this information + * is only valid while holding the PT lock. */ - page_locked = trylock_page(page); - target_nid = mpol_misplaced(page, vma, haddr); - if (target_nid == -1) { - /* If the page was locked, there are no parallel migrations */ - if (page_locked) - goto clear_pmdnuma; - } - - /* Migration could have started since the pmd_trans_migrating check */ - if (!page_locked) { - page_nid = -1; - if (!get_page_unless_zero(page)) - goto out_unlock; - spin_unlock(vmf->ptl); - put_and_wait_on_page_locked(page); - goto out; + writable = pmd_write(pmd); + if (!writable && vma_wants_manual_pte_write_upgrade(vma) && + can_change_pmd_writable(vma, vmf->address, pmd)) + writable = true; + + folio = vm_normal_folio_pmd(vma, haddr, pmd); + if (!folio) + goto out_map; + + nid = folio_nid(folio); + + target_nid = numa_migrate_check(folio, vmf, haddr, &flags, writable, + &last_cpupid); + if (target_nid == NUMA_NO_NODE) + goto out_map; + if (migrate_misplaced_folio_prepare(folio, vma, target_nid)) { + flags |= TNF_MIGRATE_FAIL; + goto out_map; } - - /* - * Page is misplaced. Page lock serialises migrations. Acquire anon_vma - * to serialises splits - */ - get_page(page); + /* The folio is isolated and isolation code holds a folio reference. */ spin_unlock(vmf->ptl); - anon_vma = page_lock_anon_vma_read(page); + writable = false; - /* Confirm the PMD did not change while page_table_lock was released */ - spin_lock(vmf->ptl); - if (unlikely(!pmd_same(pmd, *vmf->pmd))) { - unlock_page(page); - put_page(page); - page_nid = -1; - goto out_unlock; - } - - /* Bail if we fail to protect against THP splits for any reason */ - if (unlikely(!anon_vma)) { - put_page(page); - page_nid = -1; - goto clear_pmdnuma; + if (!migrate_misplaced_folio(folio, target_nid)) { + flags |= TNF_MIGRATED; + nid = target_nid; + task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); + return 0; } - /* - * Since we took the NUMA fault, we must have observed the !accessible - * bit. Make sure all other CPUs agree with that, to avoid them - * modifying the page we're about to migrate. - * - * Must be done under PTL such that we'll observe the relevant - * inc_tlb_flush_pending(). - * - * We are not sure a pending tlb flush here is for a huge page - * mapping or not. Hence use the tlb range variant - */ - if (mm_tlb_flush_pending(vma->vm_mm)) { - flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); - /* - * change_huge_pmd() released the pmd lock before - * invalidating the secondary MMUs sharing the primary - * MMU pagetables (with ->invalidate_range()). The - * mmu_notifier_invalidate_range_end() (which - * internally calls ->invalidate_range()) in - * change_pmd_range() will run after us, so we can't - * rely on it here and we need an explicit invalidate. - */ - mmu_notifier_invalidate_range(vma->vm_mm, haddr, - haddr + HPAGE_PMD_SIZE); + flags |= TNF_MIGRATE_FAIL; + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd))) { + spin_unlock(vmf->ptl); + return 0; } - - /* - * Migrate the THP to the requested node, returns with page unlocked - * and access rights restored. - */ - spin_unlock(vmf->ptl); - - migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, - vmf->pmd, pmd, vmf->address, page, target_nid); - if (migrated) { - flags |= TNF_MIGRATED; - page_nid = target_nid; - } else - flags |= TNF_MIGRATE_FAIL; - - goto out; -clear_pmdnuma: - BUG_ON(!PageLocked(page)); - was_writable = pmd_savedwrite(pmd); - pmd = pmd_modify(pmd, vma->vm_page_prot); +out_map: + /* Restore the PMD */ + pmd = pmd_modify(pmdp_get(vmf->pmd), vma->vm_page_prot); pmd = pmd_mkyoung(pmd); - if (was_writable) - pmd = pmd_mkwrite(pmd); + if (writable) + pmd = pmd_mkwrite(pmd, vma); set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); - unlock_page(page); -out_unlock: spin_unlock(vmf->ptl); -out: - if (anon_vma) - page_unlock_anon_vma_read(anon_vma); - - if (page_nid != -1) - task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, - flags); - + if (nid != NUMA_NO_NODE) + task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); return 0; } @@ -1634,11 +2264,11 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, { spinlock_t *ptl; pmd_t orig_pmd; - struct page *page; + struct folio *folio; struct mm_struct *mm = tlb->mm; bool ret = false; - tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE); + tlb_change_page_size(tlb, HPAGE_PMD_SIZE); ptl = pmd_trans_huge_lock(pmd, vma); if (!ptl) @@ -1650,19 +2280,19 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, if (unlikely(!pmd_present(orig_pmd))) { VM_BUG_ON(thp_migration_supported() && - !is_pmd_migration_entry(orig_pmd)); + !pmd_is_migration_entry(orig_pmd)); goto out; } - page = pmd_page(orig_pmd); + folio = pmd_folio(orig_pmd); /* - * If other processes are mapping this page, we couldn't discard - * the page unless they all do MADV_FREE so let's skip the page. + * If other processes are mapping this folio, we couldn't discard + * the folio unless they all do MADV_FREE so let's skip the folio. */ - if (page_mapcount(page) != 1) + if (folio_maybe_mapped_shared(folio)) goto out; - if (!trylock_page(page)) + if (!folio_trylock(folio)) goto out; /* @@ -1670,17 +2300,17 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, * will deactivate only them. */ if (next - addr != HPAGE_PMD_SIZE) { - get_page(page); + folio_get(folio); spin_unlock(ptl); - split_huge_page(page); - unlock_page(page); - put_page(page); + split_folio(folio); + folio_unlock(folio); + folio_put(folio); goto out_unlocked; } - if (PageDirty(page)) - ClearPageDirty(page); - unlock_page(page); + if (folio_test_dirty(folio)) + folio_clear_dirty(folio); + folio_unlock(folio); if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { pmdp_invalidate(vma, addr, pmd); @@ -1691,7 +2321,7 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, tlb_remove_pmd_tlb_entry(tlb, pmd, addr); } - mark_page_lazyfree(page); + folio_mark_lazyfree(folio); ret = true; out: spin_unlock(ptl); @@ -1714,7 +2344,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t orig_pmd; spinlock_t *ptl; - tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE); + tlb_change_page_size(tlb, HPAGE_PMD_SIZE); ptl = __pmd_trans_huge_lock(pmd, vma); if (!ptl) @@ -1725,50 +2355,66 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, * pgtable_trans_huge_withdraw after finishing pmdp related * operations. */ - orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, - tlb->fullmm); + orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, + tlb->fullmm); + arch_check_zapped_pmd(vma, orig_pmd); tlb_remove_pmd_tlb_entry(tlb, pmd, addr); - if (vma_is_dax(vma)) { + if (!vma_is_dax(vma) && vma_is_special_huge(vma)) { if (arch_needs_pgtable_deposit()) zap_deposited_table(tlb->mm, pmd); spin_unlock(ptl); - if (is_huge_zero_pmd(orig_pmd)) - tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); } else if (is_huge_zero_pmd(orig_pmd)) { - zap_deposited_table(tlb->mm, pmd); + if (!vma_is_dax(vma) || arch_needs_pgtable_deposit()) + zap_deposited_table(tlb->mm, pmd); spin_unlock(ptl); - tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); } else { - struct page *page = NULL; + struct folio *folio = NULL; int flush_needed = 1; if (pmd_present(orig_pmd)) { - page = pmd_page(orig_pmd); - page_remove_rmap(page, true); - VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); + struct page *page = pmd_page(orig_pmd); + + folio = page_folio(page); + folio_remove_rmap_pmd(folio, page, vma); + WARN_ON_ONCE(folio_mapcount(folio) < 0); VM_BUG_ON_PAGE(!PageHead(page), page); - } else if (thp_migration_supported()) { - swp_entry_t entry; + } else if (pmd_is_valid_softleaf(orig_pmd)) { + const softleaf_t entry = softleaf_from_pmd(orig_pmd); - VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); - entry = pmd_to_swp_entry(orig_pmd); - page = pfn_to_page(swp_offset(entry)); + folio = softleaf_to_folio(entry); flush_needed = 0; - } else - WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); - if (PageAnon(page)) { + if (!thp_migration_supported()) + WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); + } + + if (folio_test_anon(folio)) { zap_deposited_table(tlb->mm, pmd); add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); } else { if (arch_needs_pgtable_deposit()) zap_deposited_table(tlb->mm, pmd); - add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); + add_mm_counter(tlb->mm, mm_counter_file(folio), + -HPAGE_PMD_NR); + + /* + * Use flush_needed to indicate whether the PMD entry + * is present, instead of checking pmd_present() again. + */ + if (flush_needed && pmd_young(orig_pmd) && + likely(vma_has_recency(vma))) + folio_mark_accessed(folio); + } + + if (folio_is_device_private(folio)) { + folio_remove_rmap_pmd(folio, &folio->page, vma); + WARN_ON_ONCE(folio_mapcount(folio) < 0); + folio_put(folio); } spin_unlock(ptl); if (flush_needed) - tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); + tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE); } return 1; } @@ -1790,41 +2436,49 @@ static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, static pmd_t move_soft_dirty_pmd(pmd_t pmd) { -#ifdef CONFIG_MEM_SOFT_DIRTY - if (unlikely(is_pmd_migration_entry(pmd))) - pmd = pmd_swp_mksoft_dirty(pmd); - else if (pmd_present(pmd)) - pmd = pmd_mksoft_dirty(pmd); -#endif + if (pgtable_supports_soft_dirty()) { + if (unlikely(pmd_is_migration_entry(pmd))) + pmd = pmd_swp_mksoft_dirty(pmd); + else if (pmd_present(pmd)) + pmd = pmd_mksoft_dirty(pmd); + } + + return pmd; +} + +static pmd_t clear_uffd_wp_pmd(pmd_t pmd) +{ + if (pmd_none(pmd)) + return pmd; + if (pmd_present(pmd)) + pmd = pmd_clear_uffd_wp(pmd); + else + pmd = pmd_swp_clear_uffd_wp(pmd); + return pmd; } bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, - unsigned long new_addr, unsigned long old_end, - pmd_t *old_pmd, pmd_t *new_pmd) + unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) { spinlock_t *old_ptl, *new_ptl; pmd_t pmd; struct mm_struct *mm = vma->vm_mm; bool force_flush = false; - if ((old_addr & ~HPAGE_PMD_MASK) || - (new_addr & ~HPAGE_PMD_MASK) || - old_end - old_addr < HPAGE_PMD_SIZE) - return false; - /* * The destination pmd shouldn't be established, free_pgtables() - * should have release it. + * should have released it; but move_page_tables() might have already + * inserted a page table, if racing against shmem/file collapse. */ - if (WARN_ON(!pmd_none(*new_pmd))) { + if (!pmd_none(*new_pmd)) { VM_BUG_ON(pmd_trans_huge(*new_pmd)); return false; } /* * We don't have to worry about the ordering of src and dst - * ptlocks because exclusive mmap_sem prevents deadlock. + * ptlocks because exclusive mmap_lock prevents deadlock. */ old_ptl = __pmd_trans_huge_lock(old_pmd, vma); if (old_ptl) { @@ -1842,9 +2496,11 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, pgtable_trans_huge_deposit(mm, new_pmd, pgtable); } pmd = move_soft_dirty_pmd(pmd); + if (vma_has_uffd_without_event_remap(vma)) + pmd = clear_uffd_wp_pmd(pmd); set_pmd_at(mm, new_addr, new_pmd, pmd); if (force_flush) - flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); + flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); if (new_ptl != old_ptl) spin_unlock(new_ptl); spin_unlock(old_ptl); @@ -1853,64 +2509,97 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, return false; } +static void change_non_present_huge_pmd(struct mm_struct *mm, + unsigned long addr, pmd_t *pmd, bool uffd_wp, + bool uffd_wp_resolve) +{ + softleaf_t entry = softleaf_from_pmd(*pmd); + const struct folio *folio = softleaf_to_folio(entry); + pmd_t newpmd; + + VM_WARN_ON(!pmd_is_valid_softleaf(*pmd)); + if (softleaf_is_migration_write(entry)) { + /* + * A protection check is difficult so + * just be safe and disable write + */ + if (folio_test_anon(folio)) + entry = make_readable_exclusive_migration_entry(swp_offset(entry)); + else + entry = make_readable_migration_entry(swp_offset(entry)); + newpmd = swp_entry_to_pmd(entry); + if (pmd_swp_soft_dirty(*pmd)) + newpmd = pmd_swp_mksoft_dirty(newpmd); + } else if (softleaf_is_device_private_write(entry)) { + entry = make_readable_device_private_entry(swp_offset(entry)); + newpmd = swp_entry_to_pmd(entry); + } else { + newpmd = *pmd; + } + + if (uffd_wp) + newpmd = pmd_swp_mkuffd_wp(newpmd); + else if (uffd_wp_resolve) + newpmd = pmd_swp_clear_uffd_wp(newpmd); + if (!pmd_same(*pmd, newpmd)) + set_pmd_at(mm, addr, pmd, newpmd); +} + /* * Returns * - 0 if PMD could not be locked - * - 1 if PMD was locked but protections unchange and TLB flush unnecessary - * - HPAGE_PMD_NR is protections changed and TLB flush necessary + * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary + * or if prot_numa but THP migration is not supported + * - HPAGE_PMD_NR if protections changed and TLB flush necessary */ -int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, - unsigned long addr, pgprot_t newprot, int prot_numa) +int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, + pmd_t *pmd, unsigned long addr, pgprot_t newprot, + unsigned long cp_flags) { struct mm_struct *mm = vma->vm_mm; spinlock_t *ptl; - pmd_t entry; - bool preserve_write; - int ret; + pmd_t oldpmd, entry; + bool prot_numa = cp_flags & MM_CP_PROT_NUMA; + bool uffd_wp = cp_flags & MM_CP_UFFD_WP; + bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; + int ret = 1; + + tlb_change_page_size(tlb, HPAGE_PMD_SIZE); + + if (prot_numa && !thp_migration_supported()) + return 1; ptl = __pmd_trans_huge_lock(pmd, vma); if (!ptl) return 0; - preserve_write = prot_numa && pmd_write(*pmd); - ret = 1; - -#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION - if (is_swap_pmd(*pmd)) { - swp_entry_t entry = pmd_to_swp_entry(*pmd); - - VM_BUG_ON(!is_pmd_migration_entry(*pmd)); - if (is_write_migration_entry(entry)) { - pmd_t newpmd; - /* - * A protection check is difficult so - * just be safe and disable write - */ - make_migration_entry_read(&entry); - newpmd = swp_entry_to_pmd(entry); - if (pmd_swp_soft_dirty(*pmd)) - newpmd = pmd_swp_mksoft_dirty(newpmd); - set_pmd_at(mm, addr, pmd, newpmd); - } + if (thp_migration_supported() && pmd_is_valid_softleaf(*pmd)) { + change_non_present_huge_pmd(mm, addr, pmd, uffd_wp, + uffd_wp_resolve); goto unlock; } -#endif - /* - * Avoid trapping faults against the zero page. The read-only - * data is likely to be read-cached on the local CPU and - * local/remote hits to the zero page are not interesting. - */ - if (prot_numa && is_huge_zero_pmd(*pmd)) - goto unlock; + if (prot_numa) { - if (prot_numa && pmd_protnone(*pmd)) - goto unlock; + /* + * Avoid trapping faults against the zero page. The read-only + * data is likely to be read-cached on the local CPU and + * local/remote hits to the zero page are not interesting. + */ + if (is_huge_zero_pmd(*pmd)) + goto unlock; + if (pmd_protnone(*pmd)) + goto unlock; + + if (!folio_can_map_prot_numa(pmd_folio(*pmd), vma, + vma_is_single_threaded_private(vma))) + goto unlock; + } /* - * In case prot_numa, we are under down_read(mmap_sem). It's critical + * In case prot_numa, we are under mmap_read_lock(mm). It's critical * to not clear pmd intermittently to avoid race with MADV_DONTNEED - * which is also under down_read(mmap_sem): + * which is also under mmap_read_lock(mm): * * CPU0: CPU1: * change_huge_pmd(prot_numa=1) @@ -1925,23 +2614,205 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, * The race makes MADV_DONTNEED miss the huge pmd and don't clear it * which may break userspace. * - * pmdp_invalidate() is required to make sure we don't miss + * pmdp_invalidate_ad() is required to make sure we don't miss * dirty/young flags set by hardware. */ - entry = pmdp_invalidate(vma, addr, pmd); + oldpmd = pmdp_invalidate_ad(vma, addr, pmd); + + entry = pmd_modify(oldpmd, newprot); + if (uffd_wp) + entry = pmd_mkuffd_wp(entry); + else if (uffd_wp_resolve) + /* + * Leave the write bit to be handled by PF interrupt + * handler, then things like COW could be properly + * handled. + */ + entry = pmd_clear_uffd_wp(entry); + + /* See change_pte_range(). */ + if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) && + can_change_pmd_writable(vma, addr, entry)) + entry = pmd_mkwrite(entry, vma); - entry = pmd_modify(entry, newprot); - if (preserve_write) - entry = pmd_mk_savedwrite(entry); ret = HPAGE_PMD_NR; set_pmd_at(mm, addr, pmd, entry); - BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); + + if (huge_pmd_needs_flush(oldpmd, entry)) + tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); unlock: spin_unlock(ptl); return ret; } /* + * Returns: + * + * - 0: if pud leaf changed from under us + * - 1: if pud can be skipped + * - HPAGE_PUD_NR: if pud was successfully processed + */ +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +int change_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, + pud_t *pudp, unsigned long addr, pgprot_t newprot, + unsigned long cp_flags) +{ + struct mm_struct *mm = vma->vm_mm; + pud_t oldpud, entry; + spinlock_t *ptl; + + tlb_change_page_size(tlb, HPAGE_PUD_SIZE); + + /* NUMA balancing doesn't apply to dax */ + if (cp_flags & MM_CP_PROT_NUMA) + return 1; + + /* + * Huge entries on userfault-wp only works with anonymous, while we + * don't have anonymous PUDs yet. + */ + if (WARN_ON_ONCE(cp_flags & MM_CP_UFFD_WP_ALL)) + return 1; + + ptl = __pud_trans_huge_lock(pudp, vma); + if (!ptl) + return 0; + + /* + * Can't clear PUD or it can race with concurrent zapping. See + * change_huge_pmd(). + */ + oldpud = pudp_invalidate(vma, addr, pudp); + entry = pud_modify(oldpud, newprot); + set_pud_at(mm, addr, pudp, entry); + tlb_flush_pud_range(tlb, addr, HPAGE_PUD_SIZE); + + spin_unlock(ptl); + return HPAGE_PUD_NR; +} +#endif + +#ifdef CONFIG_USERFAULTFD +/* + * The PT lock for src_pmd and dst_vma/src_vma (for reading) are locked by + * the caller, but it must return after releasing the page_table_lock. + * Just move the page from src_pmd to dst_pmd if possible. + * Return zero if succeeded in moving the page, -EAGAIN if it needs to be + * repeated by the caller, or other errors in case of failure. + */ +int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval, + struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, + unsigned long dst_addr, unsigned long src_addr) +{ + pmd_t _dst_pmd, src_pmdval; + struct page *src_page; + struct folio *src_folio; + spinlock_t *src_ptl, *dst_ptl; + pgtable_t src_pgtable; + struct mmu_notifier_range range; + int err = 0; + + src_pmdval = *src_pmd; + src_ptl = pmd_lockptr(mm, src_pmd); + + lockdep_assert_held(src_ptl); + vma_assert_locked(src_vma); + vma_assert_locked(dst_vma); + + /* Sanity checks before the operation */ + if (WARN_ON_ONCE(!pmd_none(dst_pmdval)) || WARN_ON_ONCE(src_addr & ~HPAGE_PMD_MASK) || + WARN_ON_ONCE(dst_addr & ~HPAGE_PMD_MASK)) { + spin_unlock(src_ptl); + return -EINVAL; + } + + if (!pmd_trans_huge(src_pmdval)) { + spin_unlock(src_ptl); + if (pmd_is_migration_entry(src_pmdval)) { + pmd_migration_entry_wait(mm, &src_pmdval); + return -EAGAIN; + } + return -ENOENT; + } + + src_page = pmd_page(src_pmdval); + + if (!is_huge_zero_pmd(src_pmdval)) { + if (unlikely(!PageAnonExclusive(src_page))) { + spin_unlock(src_ptl); + return -EBUSY; + } + + src_folio = page_folio(src_page); + folio_get(src_folio); + } else + src_folio = NULL; + + spin_unlock(src_ptl); + + flush_cache_range(src_vma, src_addr, src_addr + HPAGE_PMD_SIZE); + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, src_addr, + src_addr + HPAGE_PMD_SIZE); + mmu_notifier_invalidate_range_start(&range); + + if (src_folio) + folio_lock(src_folio); + + dst_ptl = pmd_lockptr(mm, dst_pmd); + double_pt_lock(src_ptl, dst_ptl); + if (unlikely(!pmd_same(*src_pmd, src_pmdval) || + !pmd_same(*dst_pmd, dst_pmdval))) { + err = -EAGAIN; + goto unlock_ptls; + } + if (src_folio) { + if (folio_maybe_dma_pinned(src_folio) || + !PageAnonExclusive(&src_folio->page)) { + err = -EBUSY; + goto unlock_ptls; + } + + if (WARN_ON_ONCE(!folio_test_head(src_folio)) || + WARN_ON_ONCE(!folio_test_anon(src_folio))) { + err = -EBUSY; + goto unlock_ptls; + } + + src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); + /* Folio got pinned from under us. Put it back and fail the move. */ + if (folio_maybe_dma_pinned(src_folio)) { + set_pmd_at(mm, src_addr, src_pmd, src_pmdval); + err = -EBUSY; + goto unlock_ptls; + } + + folio_move_anon_rmap(src_folio, dst_vma); + src_folio->index = linear_page_index(dst_vma, dst_addr); + + _dst_pmd = folio_mk_pmd(src_folio, dst_vma->vm_page_prot); + /* Follow mremap() behavior and treat the entry dirty after the move */ + _dst_pmd = pmd_mkwrite(pmd_mkdirty(_dst_pmd), dst_vma); + } else { + src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); + _dst_pmd = folio_mk_pmd(src_folio, dst_vma->vm_page_prot); + } + set_pmd_at(mm, dst_addr, dst_pmd, _dst_pmd); + + src_pgtable = pgtable_trans_huge_withdraw(mm, src_pmd); + pgtable_trans_huge_deposit(mm, dst_pmd, src_pgtable); +unlock_ptls: + double_pt_unlock(src_ptl, dst_ptl); + /* unblock rmap walks */ + if (src_folio) + folio_unlock(src_folio); + mmu_notifier_invalidate_range_end(&range); + if (src_folio) + folio_put(src_folio); + return err; +} +#endif /* CONFIG_USERFAULTFD */ + +/* * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. * * Note that if it returns page table lock pointer, this routine returns without @@ -1950,26 +2821,26 @@ unlock: spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) { spinlock_t *ptl; + ptl = pmd_lock(vma->vm_mm, pmd); - if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || - pmd_devmap(*pmd))) + if (likely(pmd_is_huge(*pmd))) return ptl; spin_unlock(ptl); return NULL; } /* - * Returns true if a given pud maps a thp, false otherwise. + * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. * - * Note that if it returns true, this routine returns without unlocking page - * table lock. So callers must unlock it. + * Note that if it returns page table lock pointer, this routine returns without + * unlocking page table lock. So callers must unlock it. */ spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) { spinlock_t *ptl; ptl = pud_lock(vma->vm_mm, pud); - if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) + if (likely(pud_trans_huge(*pud))) return ptl; spin_unlock(ptl); return NULL; @@ -1979,27 +2850,34 @@ spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, pud_t *pud, unsigned long addr) { - pud_t orig_pud; spinlock_t *ptl; + pud_t orig_pud; ptl = __pud_trans_huge_lock(pud, vma); if (!ptl) return 0; - /* - * For architectures like ppc64 we look at deposited pgtable - * when calling pudp_huge_get_and_clear. So do the - * pgtable_trans_huge_withdraw after finishing pudp related - * operations. - */ - orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud, - tlb->fullmm); + + orig_pud = pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm); + arch_check_zapped_pud(vma, orig_pud); tlb_remove_pud_tlb_entry(tlb, pud, addr); - if (vma_is_dax(vma)) { + if (!vma_is_dax(vma) && vma_is_special_huge(vma)) { spin_unlock(ptl); /* No zero page support yet */ } else { - /* No support for anonymous PUD pages yet */ - BUG(); + struct page *page = NULL; + struct folio *folio; + + /* No support for anonymous PUD pages or migration yet */ + VM_WARN_ON_ONCE(vma_is_anonymous(vma) || + !pud_present(orig_pud)); + + page = pud_page(orig_pud); + folio = page_folio(page); + folio_remove_rmap_pud(folio, page, vma); + add_mm_counter(tlb->mm, mm_counter_file(folio), -HPAGE_PUD_NR); + + spin_unlock(ptl); + tlb_remove_page_size(tlb, page, HPAGE_PUD_SIZE); } return 1; } @@ -2007,14 +2885,33 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, unsigned long haddr) { + struct folio *folio; + struct page *page; + pud_t old_pud; + VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); VM_BUG_ON_VMA(vma->vm_start > haddr, vma); VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); - VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); + VM_BUG_ON(!pud_trans_huge(*pud)); count_vm_event(THP_SPLIT_PUD); - pudp_huge_clear_flush_notify(vma, haddr, pud); + old_pud = pudp_huge_clear_flush(vma, haddr, pud); + + if (!vma_is_dax(vma)) + return; + + page = pud_page(old_pud); + folio = page_folio(page); + + if (!folio_test_dirty(folio) && pud_dirty(old_pud)) + folio_mark_dirty(folio); + if (!folio_test_referenced(folio) && pud_young(old_pud)) + folio_set_referenced(folio); + folio_remove_rmap_pud(folio, page, vma); + folio_put(folio); + add_mm_counter(vma->vm_mm, mm_counter_file(folio), + -HPAGE_PUD_NR); } void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, @@ -2023,21 +2920,23 @@ void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, spinlock_t *ptl; struct mmu_notifier_range range; - mmu_notifier_range_init(&range, vma->vm_mm, address & HPAGE_PUD_MASK, + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, + address & HPAGE_PUD_MASK, (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); mmu_notifier_invalidate_range_start(&range); ptl = pud_lock(vma->vm_mm, pud); - if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) + if (unlikely(!pud_trans_huge(*pud))) goto out; __split_huge_pud_locked(vma, pud, range.start); out: spin_unlock(ptl); - /* - * No need to double call mmu_notifier->invalidate_range() callback as - * the above pudp_huge_clear_flush_notify() did already call it. - */ - mmu_notifier_invalidate_range_only_end(&range); + mmu_notifier_invalidate_range_end(&range); +} +#else +void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, + unsigned long address) +{ } #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ @@ -2046,7 +2945,9 @@ static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, { struct mm_struct *mm = vma->vm_mm; pgtable_t pgtable; - pmd_t _pmd; + pmd_t _pmd, old_pmd; + unsigned long addr; + pte_t *pte; int i; /* @@ -2055,22 +2956,27 @@ static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, * replacing a zero pmd write protected page with a zero pte write * protected page. * - * See Documentation/vm/mmu_notifier.rst + * See Documentation/mm/mmu_notifier.rst */ - pmdp_huge_clear_flush(vma, haddr, pmd); + old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); pgtable = pgtable_trans_huge_withdraw(mm, pmd); pmd_populate(mm, &_pmd, pgtable); - for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { - pte_t *pte, entry; - entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); + pte = pte_offset_map(&_pmd, haddr); + VM_BUG_ON(!pte); + for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { + pte_t entry; + + entry = pfn_pte(my_zero_pfn(addr), vma->vm_page_prot); entry = pte_mkspecial(entry); - pte = pte_offset_map(&_pmd, haddr); - VM_BUG_ON(!pte_none(*pte)); - set_pte_at(mm, haddr, pte, entry); - pte_unmap(pte); + if (pmd_uffd_wp(old_pmd)) + entry = pte_mkuffd_wp(entry); + VM_BUG_ON(!pte_none(ptep_get(pte))); + set_pte_at(mm, addr, pte, entry); + pte++; } + pte_unmap(pte - 1); smp_wmb(); /* make pte visible before pmd */ pmd_populate(mm, pmd, pgtable); } @@ -2079,45 +2985,59 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, unsigned long haddr, bool freeze) { struct mm_struct *mm = vma->vm_mm; + struct folio *folio; struct page *page; pgtable_t pgtable; pmd_t old_pmd, _pmd; - bool young, write, soft_dirty, pmd_migration = false; + bool soft_dirty, uffd_wp = false, young = false, write = false; + bool anon_exclusive = false, dirty = false; unsigned long addr; + pte_t *pte; int i; VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); VM_BUG_ON_VMA(vma->vm_start > haddr, vma); VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); - VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) - && !pmd_devmap(*pmd)); + + VM_WARN_ON_ONCE(!pmd_is_valid_softleaf(*pmd) && !pmd_trans_huge(*pmd)); count_vm_event(THP_SPLIT_PMD); if (!vma_is_anonymous(vma)) { - _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); + old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); /* * We are going to unmap this huge page. So * just go ahead and zap it */ if (arch_needs_pgtable_deposit()) zap_deposited_table(mm, pmd); - if (vma_is_dax(vma)) + if (!vma_is_dax(vma) && vma_is_special_huge(vma)) return; - page = pmd_page(_pmd); - if (!PageDirty(page) && pmd_dirty(_pmd)) - set_page_dirty(page); - if (!PageReferenced(page) && pmd_young(_pmd)) - SetPageReferenced(page); - page_remove_rmap(page, true); - put_page(page); - add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); + if (unlikely(pmd_is_migration_entry(old_pmd))) { + const softleaf_t old_entry = softleaf_from_pmd(old_pmd); + + folio = softleaf_to_folio(old_entry); + } else if (is_huge_zero_pmd(old_pmd)) { + return; + } else { + page = pmd_page(old_pmd); + folio = page_folio(page); + if (!folio_test_dirty(folio) && pmd_dirty(old_pmd)) + folio_mark_dirty(folio); + if (!folio_test_referenced(folio) && pmd_young(old_pmd)) + folio_set_referenced(folio); + folio_remove_rmap_pmd(folio, page, vma); + folio_put(folio); + } + add_mm_counter(mm, mm_counter_file(folio), -HPAGE_PMD_NR); return; - } else if (is_huge_zero_pmd(*pmd)) { + } + + if (is_huge_zero_pmd(*pmd)) { /* * FIXME: Do we want to invalidate secondary mmu by calling - * mmu_notifier_invalidate_range() see comments below inside - * __split_huge_pmd() ? + * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below + * inside __split_huge_pmd() ? * * We are going from a zero huge page write protected to zero * small page also write protected so it does not seems useful @@ -2126,47 +3046,122 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, return __split_huge_zero_page_pmd(vma, haddr, pmd); } - /* - * Up to this point the pmd is present and huge and userland has the - * whole access to the hugepage during the split (which happens in - * place). If we overwrite the pmd with the not-huge version pointing - * to the pte here (which of course we could if all CPUs were bug - * free), userland could trigger a small page size TLB miss on the - * small sized TLB while the hugepage TLB entry is still established in - * the huge TLB. Some CPU doesn't like that. - * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum - * 383 on page 93. Intel should be safe but is also warns that it's - * only safe if the permission and cache attributes of the two entries - * loaded in the two TLB is identical (which should be the case here). - * But it is generally safer to never allow small and huge TLB entries - * for the same virtual address to be loaded simultaneously. So instead - * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the - * current pmd notpresent (atomically because here the pmd_trans_huge - * must remain set at all times on the pmd until the split is complete - * for this pmd), then we flush the SMP TLB and finally we write the - * non-huge version of the pmd entry with pmd_populate. - */ - old_pmd = pmdp_invalidate(vma, haddr, pmd); + if (pmd_is_migration_entry(*pmd)) { + softleaf_t entry; - pmd_migration = is_pmd_migration_entry(old_pmd); - if (unlikely(pmd_migration)) { - swp_entry_t entry; + old_pmd = *pmd; + entry = softleaf_from_pmd(old_pmd); + page = softleaf_to_page(entry); + folio = page_folio(page); - entry = pmd_to_swp_entry(old_pmd); - page = pfn_to_page(swp_offset(entry)); - write = is_write_migration_entry(entry); - young = false; soft_dirty = pmd_swp_soft_dirty(old_pmd); + uffd_wp = pmd_swp_uffd_wp(old_pmd); + + write = softleaf_is_migration_write(entry); + if (PageAnon(page)) + anon_exclusive = softleaf_is_migration_read_exclusive(entry); + young = softleaf_is_migration_young(entry); + dirty = softleaf_is_migration_dirty(entry); + } else if (pmd_is_device_private_entry(*pmd)) { + softleaf_t entry; + + old_pmd = *pmd; + entry = softleaf_from_pmd(old_pmd); + page = softleaf_to_page(entry); + folio = page_folio(page); + + soft_dirty = pmd_swp_soft_dirty(old_pmd); + uffd_wp = pmd_swp_uffd_wp(old_pmd); + + write = softleaf_is_device_private_write(entry); + anon_exclusive = PageAnonExclusive(page); + + /* + * Device private THP should be treated the same as regular + * folios w.r.t anon exclusive handling. See the comments for + * folio handling and anon_exclusive below. + */ + if (freeze && anon_exclusive && + folio_try_share_anon_rmap_pmd(folio, page)) + freeze = false; + if (!freeze) { + rmap_t rmap_flags = RMAP_NONE; + + folio_ref_add(folio, HPAGE_PMD_NR - 1); + if (anon_exclusive) + rmap_flags |= RMAP_EXCLUSIVE; + + folio_add_anon_rmap_ptes(folio, page, HPAGE_PMD_NR, + vma, haddr, rmap_flags); + } } else { + /* + * Up to this point the pmd is present and huge and userland has + * the whole access to the hugepage during the split (which + * happens in place). If we overwrite the pmd with the not-huge + * version pointing to the pte here (which of course we could if + * all CPUs were bug free), userland could trigger a small page + * size TLB miss on the small sized TLB while the hugepage TLB + * entry is still established in the huge TLB. Some CPU doesn't + * like that. See + * http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum + * 383 on page 105. Intel should be safe but is also warns that + * it's only safe if the permission and cache attributes of the + * two entries loaded in the two TLB is identical (which should + * be the case here). But it is generally safer to never allow + * small and huge TLB entries for the same virtual address to be + * loaded simultaneously. So instead of doing "pmd_populate(); + * flush_pmd_tlb_range();" we first mark the current pmd + * notpresent (atomically because here the pmd_trans_huge must + * remain set at all times on the pmd until the split is + * complete for this pmd), then we flush the SMP TLB and finally + * we write the non-huge version of the pmd entry with + * pmd_populate. + */ + old_pmd = pmdp_invalidate(vma, haddr, pmd); page = pmd_page(old_pmd); - if (pmd_dirty(old_pmd)) - SetPageDirty(page); + folio = page_folio(page); + if (pmd_dirty(old_pmd)) { + dirty = true; + folio_set_dirty(folio); + } write = pmd_write(old_pmd); young = pmd_young(old_pmd); soft_dirty = pmd_soft_dirty(old_pmd); + uffd_wp = pmd_uffd_wp(old_pmd); + + VM_WARN_ON_FOLIO(!folio_ref_count(folio), folio); + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + + /* + * Without "freeze", we'll simply split the PMD, propagating the + * PageAnonExclusive() flag for each PTE by setting it for + * each subpage -- no need to (temporarily) clear. + * + * With "freeze" we want to replace mapped pages by + * migration entries right away. This is only possible if we + * managed to clear PageAnonExclusive() -- see + * set_pmd_migration_entry(). + * + * In case we cannot clear PageAnonExclusive(), split the PMD + * only and let try_to_migrate_one() fail later. + * + * See folio_try_share_anon_rmap_pmd(): invalidate PMD first. + */ + anon_exclusive = PageAnonExclusive(page); + if (freeze && anon_exclusive && + folio_try_share_anon_rmap_pmd(folio, page)) + freeze = false; + if (!freeze) { + rmap_t rmap_flags = RMAP_NONE; + + folio_ref_add(folio, HPAGE_PMD_NR - 1); + if (anon_exclusive) + rmap_flags |= RMAP_EXCLUSIVE; + folio_add_anon_rmap_ptes(folio, page, HPAGE_PMD_NR, + vma, haddr, rmap_flags); + } } - VM_BUG_ON_PAGE(!page_count(page), page); - page_ref_add(page, HPAGE_PMD_NR - 1); /* * Withdraw the table only after we mark the pmd entry invalid. @@ -2175,562 +3170,920 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pgtable = pgtable_trans_huge_withdraw(mm, pmd); pmd_populate(mm, &_pmd, pgtable); - for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { - pte_t entry, *pte; - /* - * Note that NUMA hinting access restrictions are not - * transferred to avoid any possibility of altering - * permissions across VMAs. - */ - if (freeze || pmd_migration) { - swp_entry_t swp_entry; - swp_entry = make_migration_entry(page + i, write); + pte = pte_offset_map(&_pmd, haddr); + VM_BUG_ON(!pte); + + /* + * Note that NUMA hinting access restrictions are not transferred to + * avoid any possibility of altering permissions across VMAs. + */ + if (freeze || pmd_is_migration_entry(old_pmd)) { + pte_t entry; + swp_entry_t swp_entry; + + for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { + if (write) + swp_entry = make_writable_migration_entry( + page_to_pfn(page + i)); + else if (anon_exclusive) + swp_entry = make_readable_exclusive_migration_entry( + page_to_pfn(page + i)); + else + swp_entry = make_readable_migration_entry( + page_to_pfn(page + i)); + if (young) + swp_entry = make_migration_entry_young(swp_entry); + if (dirty) + swp_entry = make_migration_entry_dirty(swp_entry); entry = swp_entry_to_pte(swp_entry); if (soft_dirty) entry = pte_swp_mksoft_dirty(entry); - } else { - entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); - entry = maybe_mkwrite(entry, vma); - if (!write) - entry = pte_wrprotect(entry); - if (!young) - entry = pte_mkold(entry); + if (uffd_wp) + entry = pte_swp_mkuffd_wp(entry); + VM_WARN_ON(!pte_none(ptep_get(pte + i))); + set_pte_at(mm, addr, pte + i, entry); + } + } else if (pmd_is_device_private_entry(old_pmd)) { + pte_t entry; + swp_entry_t swp_entry; + + for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { + /* + * anon_exclusive was already propagated to the relevant + * pages corresponding to the pte entries when freeze + * is false. + */ + if (write) + swp_entry = make_writable_device_private_entry( + page_to_pfn(page + i)); + else + swp_entry = make_readable_device_private_entry( + page_to_pfn(page + i)); + /* + * Young and dirty bits are not progated via swp_entry + */ + entry = swp_entry_to_pte(swp_entry); if (soft_dirty) - entry = pte_mksoft_dirty(entry); + entry = pte_swp_mksoft_dirty(entry); + if (uffd_wp) + entry = pte_swp_mkuffd_wp(entry); + VM_WARN_ON(!pte_none(ptep_get(pte + i))); + set_pte_at(mm, addr, pte + i, entry); } - pte = pte_offset_map(&_pmd, addr); - BUG_ON(!pte_none(*pte)); - set_pte_at(mm, addr, pte, entry); - atomic_inc(&page[i]._mapcount); - pte_unmap(pte); - } + } else { + pte_t entry; + + entry = mk_pte(page, READ_ONCE(vma->vm_page_prot)); + if (write) + entry = pte_mkwrite(entry, vma); + if (!young) + entry = pte_mkold(entry); + /* NOTE: this may set soft-dirty too on some archs */ + if (dirty) + entry = pte_mkdirty(entry); + if (soft_dirty) + entry = pte_mksoft_dirty(entry); + if (uffd_wp) + entry = pte_mkuffd_wp(entry); - /* - * Set PG_double_map before dropping compound_mapcount to avoid - * false-negative page_mapped(). - */ - if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { for (i = 0; i < HPAGE_PMD_NR; i++) - atomic_inc(&page[i]._mapcount); - } + VM_WARN_ON(!pte_none(ptep_get(pte + i))); - if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { - /* Last compound_mapcount is gone. */ - __dec_node_page_state(page, NR_ANON_THPS); - if (TestClearPageDoubleMap(page)) { - /* No need in mapcount reference anymore */ - for (i = 0; i < HPAGE_PMD_NR; i++) - atomic_dec(&page[i]._mapcount); - } + set_ptes(mm, haddr, pte, entry, HPAGE_PMD_NR); } + pte_unmap(pte); + + if (!pmd_is_migration_entry(*pmd)) + folio_remove_rmap_pmd(folio, page, vma); + if (freeze) + put_page(page); smp_wmb(); /* make pte visible before pmd */ pmd_populate(mm, pmd, pgtable); +} - if (freeze) { - for (i = 0; i < HPAGE_PMD_NR; i++) { - page_remove_rmap(page + i, false); - put_page(page + i); - } - } +void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmd, bool freeze) +{ + VM_WARN_ON_ONCE(!IS_ALIGNED(address, HPAGE_PMD_SIZE)); + if (pmd_trans_huge(*pmd) || pmd_is_valid_softleaf(*pmd)) + __split_huge_pmd_locked(vma, pmd, address, freeze); } void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, - unsigned long address, bool freeze, struct page *page) + unsigned long address, bool freeze) { spinlock_t *ptl; struct mmu_notifier_range range; - mmu_notifier_range_init(&range, vma->vm_mm, address & HPAGE_PMD_MASK, + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, + address & HPAGE_PMD_MASK, (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); mmu_notifier_invalidate_range_start(&range); ptl = pmd_lock(vma->vm_mm, pmd); - - /* - * If caller asks to setup a migration entries, we need a page to check - * pmd against. Otherwise we can end up replacing wrong page. - */ - VM_BUG_ON(freeze && !page); - if (page && page != pmd_page(*pmd)) - goto out; - - if (pmd_trans_huge(*pmd)) { - page = pmd_page(*pmd); - if (PageMlocked(page)) - clear_page_mlock(page); - } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) - goto out; - __split_huge_pmd_locked(vma, pmd, range.start, freeze); -out: + split_huge_pmd_locked(vma, range.start, pmd, freeze); spin_unlock(ptl); - /* - * No need to double call mmu_notifier->invalidate_range() callback. - * They are 3 cases to consider inside __split_huge_pmd_locked(): - * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious - * 2) __split_huge_zero_page_pmd() read only zero page and any write - * fault will trigger a flush_notify before pointing to a new page - * (it is fine if the secondary mmu keeps pointing to the old zero - * page in the meantime) - * 3) Split a huge pmd into pte pointing to the same page. No need - * to invalidate secondary tlb entry they are all still valid. - * any further changes to individual pte will notify. So no need - * to call mmu_notifier->invalidate_range() - */ - mmu_notifier_invalidate_range_only_end(&range); + mmu_notifier_invalidate_range_end(&range); } void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, - bool freeze, struct page *page) + bool freeze) { - pgd_t *pgd; - p4d_t *p4d; - pud_t *pud; - pmd_t *pmd; + pmd_t *pmd = mm_find_pmd(vma->vm_mm, address); - pgd = pgd_offset(vma->vm_mm, address); - if (!pgd_present(*pgd)) + if (!pmd) return; - p4d = p4d_offset(pgd, address); - if (!p4d_present(*p4d)) - return; - - pud = pud_offset(p4d, address); - if (!pud_present(*pud)) - return; - - pmd = pmd_offset(pud, address); - - __split_huge_pmd(vma, pmd, address, freeze, page); + __split_huge_pmd(vma, pmd, address, freeze); } -void vma_adjust_trans_huge(struct vm_area_struct *vma, - unsigned long start, - unsigned long end, - long adjust_next) +static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) { /* - * If the new start address isn't hpage aligned and it could - * previously contain an hugepage: check if we need to split - * an huge pmd. + * If the new address isn't hpage aligned and it could previously + * contain an hugepage: check if we need to split an huge pmd. */ - if (start & ~HPAGE_PMD_MASK && - (start & HPAGE_PMD_MASK) >= vma->vm_start && - (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) - split_huge_pmd_address(vma, start, false, NULL); + if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && + range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), + ALIGN(address, HPAGE_PMD_SIZE))) + split_huge_pmd_address(vma, address, false); +} - /* - * If the new end address isn't hpage aligned and it could - * previously contain an hugepage: check if we need to split - * an huge pmd. - */ - if (end & ~HPAGE_PMD_MASK && - (end & HPAGE_PMD_MASK) >= vma->vm_start && - (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) - split_huge_pmd_address(vma, end, false, NULL); +void vma_adjust_trans_huge(struct vm_area_struct *vma, + unsigned long start, + unsigned long end, + struct vm_area_struct *next) +{ + /* Check if we need to split start first. */ + split_huge_pmd_if_needed(vma, start); - /* - * If we're also updating the vma->vm_next->vm_start, if the new - * vm_next->vm_start isn't page aligned and it could previously - * contain an hugepage: check if we need to split an huge pmd. - */ - if (adjust_next > 0) { - struct vm_area_struct *next = vma->vm_next; - unsigned long nstart = next->vm_start; - nstart += adjust_next << PAGE_SHIFT; - if (nstart & ~HPAGE_PMD_MASK && - (nstart & HPAGE_PMD_MASK) >= next->vm_start && - (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) - split_huge_pmd_address(next, nstart, false, NULL); - } + /* Check if we need to split end next. */ + split_huge_pmd_if_needed(vma, end); + + /* If we're incrementing next->vm_start, we might need to split it. */ + if (next) + split_huge_pmd_if_needed(next, end); } -static void unmap_page(struct page *page) +static void unmap_folio(struct folio *folio) { - enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | - TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD; - bool unmap_success; + enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SYNC | + TTU_BATCH_FLUSH; - VM_BUG_ON_PAGE(!PageHead(page), page); + VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); + + if (folio_test_pmd_mappable(folio)) + ttu_flags |= TTU_SPLIT_HUGE_PMD; - if (PageAnon(page)) - ttu_flags |= TTU_SPLIT_FREEZE; + /* + * Anon pages need migration entries to preserve them, but file + * pages can simply be left unmapped, then faulted back on demand. + * If that is ever changed (perhaps for mlock), update remap_page(). + */ + if (folio_test_anon(folio)) + try_to_migrate(folio, ttu_flags); + else + try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); - unmap_success = try_to_unmap(page, ttu_flags); - VM_BUG_ON_PAGE(!unmap_success, page); + try_to_unmap_flush(); } -static void remap_page(struct page *page) +static bool __discard_anon_folio_pmd_locked(struct vm_area_struct *vma, + unsigned long addr, pmd_t *pmdp, + struct folio *folio) { - int i; - if (PageTransHuge(page)) { - remove_migration_ptes(page, page, true); - } else { - for (i = 0; i < HPAGE_PMD_NR; i++) - remove_migration_ptes(page + i, page + i, true); + struct mm_struct *mm = vma->vm_mm; + int ref_count, map_count; + pmd_t orig_pmd = *pmdp; + + if (pmd_dirty(orig_pmd)) + folio_set_dirty(folio); + if (folio_test_dirty(folio) && !(vma->vm_flags & VM_DROPPABLE)) { + folio_set_swapbacked(folio); + return false; } -} -static void __split_huge_page_tail(struct page *head, int tail, - struct lruvec *lruvec, struct list_head *list) -{ - struct page *page_tail = head + tail; + orig_pmd = pmdp_huge_clear_flush(vma, addr, pmdp); + + /* + * Syncing against concurrent GUP-fast: + * - clear PMD; barrier; read refcount + * - inc refcount; barrier; read PMD + */ + smp_mb(); - VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); + ref_count = folio_ref_count(folio); + map_count = folio_mapcount(folio); /* - * Clone page flags before unfreezing refcount. - * - * After successful get_page_unless_zero() might follow flags change, - * for exmaple lock_page() which set PG_waiters. + * Order reads for folio refcount and dirty flag + * (see comments in __remove_mapping()). */ - page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; - page_tail->flags |= (head->flags & - ((1L << PG_referenced) | - (1L << PG_swapbacked) | - (1L << PG_swapcache) | - (1L << PG_mlocked) | - (1L << PG_uptodate) | - (1L << PG_active) | - (1L << PG_workingset) | - (1L << PG_locked) | - (1L << PG_unevictable) | - (1L << PG_dirty))); - - /* ->mapping in first tail page is compound_mapcount */ - VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, - page_tail); - page_tail->mapping = head->mapping; - page_tail->index = head->index + tail; - - /* Page flags must be visible before we make the page non-compound. */ - smp_wmb(); + smp_rmb(); /* - * Clear PageTail before unfreezing page refcount. + * If the folio or its PMD is redirtied at this point, or if there + * are unexpected references, we will give up to discard this folio + * and remap it. * - * After successful get_page_unless_zero() might follow put_page() - * which needs correct compound_head(). + * The only folio refs must be one from isolation plus the rmap(s). */ - clear_compound_head(page_tail); - - /* Finally unfreeze refcount. Additional reference from page cache. */ - page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || - PageSwapCache(head))); + if (pmd_dirty(orig_pmd)) + folio_set_dirty(folio); + if (folio_test_dirty(folio) && !(vma->vm_flags & VM_DROPPABLE)) { + folio_set_swapbacked(folio); + set_pmd_at(mm, addr, pmdp, orig_pmd); + return false; + } - if (page_is_young(head)) - set_page_young(page_tail); - if (page_is_idle(head)) - set_page_idle(page_tail); + if (ref_count != map_count + 1) { + set_pmd_at(mm, addr, pmdp, orig_pmd); + return false; + } - page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); + folio_remove_rmap_pmd(folio, pmd_page(orig_pmd), vma); + zap_deposited_table(mm, pmdp); + add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR); + if (vma->vm_flags & VM_LOCKED) + mlock_drain_local(); + folio_put(folio); - /* - * always add to the tail because some iterators expect new - * pages to show after the currently processed elements - e.g. - * migrate_pages - */ - lru_add_page_tail(head, page_tail, lruvec, list); + return true; } -static void __split_huge_page(struct page *page, struct list_head *list, - pgoff_t end, unsigned long flags) +bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr, + pmd_t *pmdp, struct folio *folio) { - struct page *head = compound_head(page); - struct zone *zone = page_zone(head); - struct lruvec *lruvec; - int i; + VM_WARN_ON_FOLIO(!folio_test_pmd_mappable(folio), folio); + VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + VM_WARN_ON_FOLIO(folio_test_swapbacked(folio), folio); + VM_WARN_ON_ONCE(!IS_ALIGNED(addr, HPAGE_PMD_SIZE)); - lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat); + return __discard_anon_folio_pmd_locked(vma, addr, pmdp, folio); +} - /* complete memcg works before add pages to LRU */ - mem_cgroup_split_huge_fixup(head); +static void remap_page(struct folio *folio, unsigned long nr, int flags) +{ + int i = 0; - for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { - __split_huge_page_tail(head, i, lruvec, list); - /* Some pages can be beyond i_size: drop them from page cache */ - if (head[i].index >= end) { - ClearPageDirty(head + i); - __delete_from_page_cache(head + i, NULL); - if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) - shmem_uncharge(head->mapping->host, 1); - put_page(head + i); - } + /* If unmap_folio() uses try_to_migrate() on file, remove this check */ + if (!folio_test_anon(folio)) + return; + for (;;) { + remove_migration_ptes(folio, folio, RMP_LOCKED | flags); + i += folio_nr_pages(folio); + if (i >= nr) + break; + folio = folio_next(folio); } +} - ClearPageCompound(head); - /* See comment in __split_huge_page_tail() */ - if (PageAnon(head)) { - /* Additional pin to swap cache */ - if (PageSwapCache(head)) - page_ref_add(head, 2); - else - page_ref_inc(head); +static void lru_add_split_folio(struct folio *folio, struct folio *new_folio, + struct lruvec *lruvec, struct list_head *list) +{ + VM_BUG_ON_FOLIO(folio_test_lru(new_folio), folio); + lockdep_assert_held(&lruvec->lru_lock); + + if (folio_is_device_private(folio)) + return; + + if (list) { + /* page reclaim is reclaiming a huge page */ + VM_WARN_ON(folio_test_lru(folio)); + folio_get(new_folio); + list_add_tail(&new_folio->lru, list); } else { - /* Additional pin to page cache */ - page_ref_add(head, 2); - xa_unlock(&head->mapping->i_pages); + /* head is still on lru (and we have it frozen) */ + VM_WARN_ON(!folio_test_lru(folio)); + if (folio_test_unevictable(folio)) + new_folio->mlock_count = 0; + else + list_add_tail(&new_folio->lru, &folio->lru); + folio_set_lru(new_folio); } +} - spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags); +/* Racy check whether the huge page can be split */ +bool can_split_folio(struct folio *folio, int caller_pins, int *pextra_pins) +{ + int extra_pins; - remap_page(head); + /* Additional pins from page cache */ + if (folio_test_anon(folio)) + extra_pins = folio_test_swapcache(folio) ? + folio_nr_pages(folio) : 0; + else + extra_pins = folio_nr_pages(folio); + if (pextra_pins) + *pextra_pins = extra_pins; + return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - + caller_pins; +} - for (i = 0; i < HPAGE_PMD_NR; i++) { - struct page *subpage = head + i; - if (subpage == page) - continue; - unlock_page(subpage); +static bool page_range_has_hwpoisoned(struct page *page, long nr_pages) +{ + for (; nr_pages; page++, nr_pages--) + if (PageHWPoison(page)) + return true; + return false; +} +/* + * It splits @folio into @new_order folios and copies the @folio metadata to + * all the resulting folios. + */ +static void __split_folio_to_order(struct folio *folio, int old_order, + int new_order) +{ + /* Scan poisoned pages when split a poisoned folio to large folios */ + const bool handle_hwpoison = folio_test_has_hwpoisoned(folio) && new_order; + long new_nr_pages = 1 << new_order; + long nr_pages = 1 << old_order; + long i; + + folio_clear_has_hwpoisoned(folio); + + /* Check first new_nr_pages since the loop below skips them */ + if (handle_hwpoison && + page_range_has_hwpoisoned(folio_page(folio, 0), new_nr_pages)) + folio_set_has_hwpoisoned(folio); + /* + * Skip the first new_nr_pages, since the new folio from them have all + * the flags from the original folio. + */ + for (i = new_nr_pages; i < nr_pages; i += new_nr_pages) { + struct page *new_head = &folio->page + i; /* - * Subpages may be freed if there wasn't any mapping - * like if add_to_swap() is running on a lru page that - * had its mapping zapped. And freeing these pages - * requires taking the lru_lock so we do the put_page - * of the tail pages after the split is complete. + * Careful: new_folio is not a "real" folio before we cleared PageTail. + * Don't pass it around before clear_compound_head(). */ - put_page(subpage); - } -} + struct folio *new_folio = (struct folio *)new_head; -int total_mapcount(struct page *page) -{ - int i, compound, ret; + VM_BUG_ON_PAGE(atomic_read(&new_folio->_mapcount) != -1, new_head); + + /* + * Clone page flags before unfreezing refcount. + * + * After successful get_page_unless_zero() might follow flags change, + * for example lock_page() which set PG_waiters. + * + * Note that for mapped sub-pages of an anonymous THP, + * PG_anon_exclusive has been cleared in unmap_folio() and is stored in + * the migration entry instead from where remap_page() will restore it. + * We can still have PG_anon_exclusive set on effectively unmapped and + * unreferenced sub-pages of an anonymous THP: we can simply drop + * PG_anon_exclusive (-> PG_mappedtodisk) for these here. + */ + new_folio->flags.f &= ~PAGE_FLAGS_CHECK_AT_PREP; + new_folio->flags.f |= (folio->flags.f & + ((1L << PG_referenced) | + (1L << PG_swapbacked) | + (1L << PG_swapcache) | + (1L << PG_mlocked) | + (1L << PG_uptodate) | + (1L << PG_active) | + (1L << PG_workingset) | + (1L << PG_locked) | + (1L << PG_unevictable) | +#ifdef CONFIG_ARCH_USES_PG_ARCH_2 + (1L << PG_arch_2) | +#endif +#ifdef CONFIG_ARCH_USES_PG_ARCH_3 + (1L << PG_arch_3) | +#endif + (1L << PG_dirty) | + LRU_GEN_MASK | LRU_REFS_MASK)); - VM_BUG_ON_PAGE(PageTail(page), page); + if (handle_hwpoison && + page_range_has_hwpoisoned(new_head, new_nr_pages)) + folio_set_has_hwpoisoned(new_folio); - if (likely(!PageCompound(page))) - return atomic_read(&page->_mapcount) + 1; + new_folio->mapping = folio->mapping; + new_folio->index = folio->index + i; - compound = compound_mapcount(page); - if (PageHuge(page)) - return compound; - ret = compound; - for (i = 0; i < HPAGE_PMD_NR; i++) - ret += atomic_read(&page[i]._mapcount) + 1; - /* File pages has compound_mapcount included in _mapcount */ - if (!PageAnon(page)) - return ret - compound * HPAGE_PMD_NR; - if (PageDoubleMap(page)) - ret -= HPAGE_PMD_NR; - return ret; + if (folio_test_swapcache(folio)) + new_folio->swap.val = folio->swap.val + i; + + /* Page flags must be visible before we make the page non-compound. */ + smp_wmb(); + + /* + * Clear PageTail before unfreezing page refcount. + * + * After successful get_page_unless_zero() might follow put_page() + * which needs correct compound_head(). + */ + clear_compound_head(new_head); + if (new_order) { + prep_compound_page(new_head, new_order); + folio_set_large_rmappable(new_folio); + } + + if (folio_test_young(folio)) + folio_set_young(new_folio); + if (folio_test_idle(folio)) + folio_set_idle(new_folio); +#ifdef CONFIG_MEMCG + new_folio->memcg_data = folio->memcg_data; +#endif + + folio_xchg_last_cpupid(new_folio, folio_last_cpupid(folio)); + } + + if (new_order) + folio_set_order(folio, new_order); + else + ClearPageCompound(&folio->page); } -/* - * This calculates accurately how many mappings a transparent hugepage - * has (unlike page_mapcount() which isn't fully accurate). This full - * accuracy is primarily needed to know if copy-on-write faults can - * reuse the page and change the mapping to read-write instead of - * copying them. At the same time this returns the total_mapcount too. +/** + * __split_unmapped_folio() - splits an unmapped @folio to lower order folios in + * two ways: uniform split or non-uniform split. + * @folio: the to-be-split folio + * @new_order: the smallest order of the after split folios (since buddy + * allocator like split generates folios with orders from @folio's + * order - 1 to new_order). + * @split_at: in buddy allocator like split, the folio containing @split_at + * will be split until its order becomes @new_order. + * @xas: xa_state pointing to folio->mapping->i_pages and locked by caller + * @mapping: @folio->mapping + * @split_type: if the split is uniform or not (buddy allocator like split) + * * - * The function returns the highest mapcount any one of the subpages - * has. If the return value is one, even if different processes are - * mapping different subpages of the transparent hugepage, they can - * all reuse it, because each process is reusing a different subpage. + * 1. uniform split: the given @folio into multiple @new_order small folios, + * where all small folios have the same order. This is done when + * split_type is SPLIT_TYPE_UNIFORM. + * 2. buddy allocator like (non-uniform) split: the given @folio is split into + * half and one of the half (containing the given page) is split into half + * until the given @folio's order becomes @new_order. This is done when + * split_type is SPLIT_TYPE_NON_UNIFORM. * - * The total_mapcount is instead counting all virtual mappings of the - * subpages. If the total_mapcount is equal to "one", it tells the - * caller all mappings belong to the same "mm" and in turn the - * anon_vma of the transparent hugepage can become the vma->anon_vma - * local one as no other process may be mapping any of the subpages. + * The high level flow for these two methods are: * - * It would be more accurate to replace page_mapcount() with - * page_trans_huge_mapcount(), however we only use - * page_trans_huge_mapcount() in the copy-on-write faults where we - * need full accuracy to avoid breaking page pinning, because - * page_trans_huge_mapcount() is slower than page_mapcount(). + * 1. uniform split: @xas is split with no expectation of failure and a single + * __split_folio_to_order() is called to split the @folio into @new_order + * along with stats update. + * 2. non-uniform split: folio_order - @new_order calls to + * __split_folio_to_order() are expected to be made in a for loop to split + * the @folio to one lower order at a time. The folio containing @split_at + * is split in each iteration. @xas is split into half in each iteration and + * can fail. A failed @xas split leaves split folios as is without merging + * them back. + * + * After splitting, the caller's folio reference will be transferred to the + * folio containing @split_at. The caller needs to unlock and/or free + * after-split folios if necessary. + * + * Return: 0 - successful, <0 - failed (if -ENOMEM is returned, @folio might be + * split but not to @new_order, the caller needs to check) */ -int page_trans_huge_mapcount(struct page *page, int *total_mapcount) +static int __split_unmapped_folio(struct folio *folio, int new_order, + struct page *split_at, struct xa_state *xas, + struct address_space *mapping, enum split_type split_type) { - int i, ret, _total_mapcount, mapcount; + const bool is_anon = folio_test_anon(folio); + int old_order = folio_order(folio); + int start_order = split_type == SPLIT_TYPE_UNIFORM ? new_order : old_order - 1; + int split_order; + + /* + * split to new_order one order at a time. For uniform split, + * folio is split to new_order directly. + */ + for (split_order = start_order; + split_order >= new_order; + split_order--) { + int nr_new_folios = 1UL << (old_order - split_order); - /* hugetlbfs shouldn't call it */ - VM_BUG_ON_PAGE(PageHuge(page), page); + /* order-1 anonymous folio is not supported */ + if (is_anon && split_order == 1) + continue; - if (likely(!PageTransCompound(page))) { - mapcount = atomic_read(&page->_mapcount) + 1; - if (total_mapcount) - *total_mapcount = mapcount; - return mapcount; + if (mapping) { + /* + * uniform split has xas_split_alloc() called before + * irq is disabled to allocate enough memory, whereas + * non-uniform split can handle ENOMEM. + */ + if (split_type == SPLIT_TYPE_UNIFORM) + xas_split(xas, folio, old_order); + else { + xas_set_order(xas, folio->index, split_order); + xas_try_split(xas, folio, old_order); + if (xas_error(xas)) + return xas_error(xas); + } + } + + folio_split_memcg_refs(folio, old_order, split_order); + split_page_owner(&folio->page, old_order, split_order); + pgalloc_tag_split(folio, old_order, split_order); + __split_folio_to_order(folio, old_order, split_order); + + if (is_anon) { + mod_mthp_stat(old_order, MTHP_STAT_NR_ANON, -1); + mod_mthp_stat(split_order, MTHP_STAT_NR_ANON, nr_new_folios); + } + /* + * If uniform split, the process is complete. + * If non-uniform, continue splitting the folio at @split_at + * as long as the next @split_order is >= @new_order. + */ + folio = page_folio(split_at); + old_order = split_order; } - page = compound_head(page); + return 0; +} - _total_mapcount = ret = 0; - for (i = 0; i < HPAGE_PMD_NR; i++) { - mapcount = atomic_read(&page[i]._mapcount) + 1; - ret = max(ret, mapcount); - _total_mapcount += mapcount; +bool folio_split_supported(struct folio *folio, unsigned int new_order, + enum split_type split_type, bool warns) +{ + if (folio_test_anon(folio)) { + /* order-1 is not supported for anonymous THP. */ + VM_WARN_ONCE(warns && new_order == 1, + "Cannot split to order-1 folio"); + if (new_order == 1) + return false; + } else if (split_type == SPLIT_TYPE_NON_UNIFORM || new_order) { + if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && + !mapping_large_folio_support(folio->mapping)) { + /* + * We can always split a folio down to a single page + * (new_order == 0) uniformly. + * + * For any other scenario + * a) uniform split targeting a large folio + * (new_order > 0) + * b) any non-uniform split + * we must confirm that the file system supports large + * folios. + * + * Note that we might still have THPs in such + * mappings, which is created from khugepaged when + * CONFIG_READ_ONLY_THP_FOR_FS is enabled. But in that + * case, the mapping does not actually support large + * folios properly. + */ + VM_WARN_ONCE(warns, + "Cannot split file folio to non-0 order"); + return false; + } } - if (PageDoubleMap(page)) { - ret -= 1; - _total_mapcount -= HPAGE_PMD_NR; + + /* + * swapcache folio could only be split to order 0 + * + * non-uniform split creates after-split folios with orders from + * folio_order(folio) - 1 to new_order, making it not suitable for any + * swapcache folio split. Only uniform split to order-0 can be used + * here. + */ + if ((split_type == SPLIT_TYPE_NON_UNIFORM || new_order) && folio_test_swapcache(folio)) { + VM_WARN_ONCE(warns, + "Cannot split swapcache folio to non-0 order"); + return false; } - mapcount = compound_mapcount(page); - ret += mapcount; - _total_mapcount += mapcount; - if (total_mapcount) - *total_mapcount = _total_mapcount; - return ret; + + return true; } -/* Racy check whether the huge page can be split */ -bool can_split_huge_page(struct page *page, int *pextra_pins) +static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int new_order, + struct page *split_at, struct xa_state *xas, + struct address_space *mapping, bool do_lru, + struct list_head *list, enum split_type split_type, + pgoff_t end, int *nr_shmem_dropped, int extra_pins) { - int extra_pins; + struct folio *end_folio = folio_next(folio); + struct folio *new_folio, *next; + int old_order = folio_order(folio); + int ret = 0; + struct deferred_split *ds_queue; - /* Additional pins from page cache */ - if (PageAnon(page)) - extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0; - else - extra_pins = HPAGE_PMD_NR; - if (pextra_pins) - *pextra_pins = extra_pins; - return total_mapcount(page) == page_count(page) - extra_pins - 1; + VM_WARN_ON_ONCE(!mapping && end); + /* Prevent deferred_split_scan() touching ->_refcount */ + ds_queue = folio_split_queue_lock(folio); + if (folio_ref_freeze(folio, 1 + extra_pins)) { + struct swap_cluster_info *ci = NULL; + struct lruvec *lruvec; + int expected_refs; + + if (old_order > 1) { + if (!list_empty(&folio->_deferred_list)) { + ds_queue->split_queue_len--; + /* + * Reinitialize page_deferred_list after removing the + * page from the split_queue, otherwise a subsequent + * split will see list corruption when checking the + * page_deferred_list. + */ + list_del_init(&folio->_deferred_list); + } + if (folio_test_partially_mapped(folio)) { + folio_clear_partially_mapped(folio); + mod_mthp_stat(old_order, + MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); + } + } + split_queue_unlock(ds_queue); + if (mapping) { + int nr = folio_nr_pages(folio); + + if (folio_test_pmd_mappable(folio) && + new_order < HPAGE_PMD_ORDER) { + if (folio_test_swapbacked(folio)) { + lruvec_stat_mod_folio(folio, + NR_SHMEM_THPS, -nr); + } else { + lruvec_stat_mod_folio(folio, + NR_FILE_THPS, -nr); + filemap_nr_thps_dec(mapping); + } + } + } + + if (folio_test_swapcache(folio)) { + if (mapping) { + VM_WARN_ON_ONCE_FOLIO(mapping, folio); + return -EINVAL; + } + + ci = swap_cluster_get_and_lock(folio); + } + + /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ + if (do_lru) + lruvec = folio_lruvec_lock(folio); + + ret = __split_unmapped_folio(folio, new_order, split_at, xas, + mapping, split_type); + + /* + * Unfreeze after-split folios and put them back to the right + * list. @folio should be kept frozon until page cache + * entries are updated with all the other after-split folios + * to prevent others seeing stale page cache entries. + * As a result, new_folio starts from the next folio of + * @folio. + */ + for (new_folio = folio_next(folio); new_folio != end_folio; + new_folio = next) { + unsigned long nr_pages = folio_nr_pages(new_folio); + + next = folio_next(new_folio); + + zone_device_private_split_cb(folio, new_folio); + + expected_refs = folio_expected_ref_count(new_folio) + 1; + folio_ref_unfreeze(new_folio, expected_refs); + + if (do_lru) + lru_add_split_folio(folio, new_folio, lruvec, list); + + /* + * Anonymous folio with swap cache. + * NOTE: shmem in swap cache is not supported yet. + */ + if (ci) { + __swap_cache_replace_folio(ci, folio, new_folio); + continue; + } + + /* Anonymous folio without swap cache */ + if (!mapping) + continue; + + /* Add the new folio to the page cache. */ + if (new_folio->index < end) { + __xa_store(&mapping->i_pages, new_folio->index, + new_folio, 0); + continue; + } + + VM_WARN_ON_ONCE(!nr_shmem_dropped); + /* Drop folio beyond EOF: ->index >= end */ + if (shmem_mapping(mapping) && nr_shmem_dropped) + *nr_shmem_dropped += nr_pages; + else if (folio_test_clear_dirty(new_folio)) + folio_account_cleaned( + new_folio, inode_to_wb(mapping->host)); + __filemap_remove_folio(new_folio, NULL); + folio_put_refs(new_folio, nr_pages); + } + + zone_device_private_split_cb(folio, NULL); + /* + * Unfreeze @folio only after all page cache entries, which + * used to point to it, have been updated with new folios. + * Otherwise, a parallel folio_try_get() can grab @folio + * and its caller can see stale page cache entries. + */ + expected_refs = folio_expected_ref_count(folio) + 1; + folio_ref_unfreeze(folio, expected_refs); + + if (do_lru) + unlock_page_lruvec(lruvec); + + if (ci) + swap_cluster_unlock(ci); + } else { + split_queue_unlock(ds_queue); + return -EAGAIN; + } + + return ret; } -/* - * This function splits huge page into normal pages. @page can point to any - * subpage of huge page to split. Split doesn't change the position of @page. +/** + * __folio_split() - split a folio at @split_at to a @new_order folio + * @folio: folio to split + * @new_order: the order of the new folio + * @split_at: a page within the new folio + * @lock_at: a page within @folio to be left locked to caller + * @list: after-split folios will be put on it if non NULL + * @split_type: perform uniform split or not (non-uniform split) * - * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. - * The huge page must be locked. + * It calls __split_unmapped_folio() to perform uniform and non-uniform split. + * It is in charge of checking whether the split is supported or not and + * preparing @folio for __split_unmapped_folio(). * - * If @list is null, tail pages will be added to LRU list, otherwise, to @list. - * - * Both head page and tail pages will inherit mapping, flags, and so on from - * the hugepage. - * - * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if - * they are not mapped. + * After splitting, the after-split folio containing @lock_at remains locked + * and others are unlocked: + * 1. for uniform split, @lock_at points to one of @folio's subpages; + * 2. for buddy allocator like (non-uniform) split, @lock_at points to @folio. * - * Returns 0 if the hugepage is split successfully. - * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under - * us. + * Return: 0 - successful, <0 - failed (if -ENOMEM is returned, @folio might be + * split but not to @new_order, the caller needs to check) */ -int split_huge_page_to_list(struct page *page, struct list_head *list) +static int __folio_split(struct folio *folio, unsigned int new_order, + struct page *split_at, struct page *lock_at, + struct list_head *list, enum split_type split_type) { - struct page *head = compound_head(page); - struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); - struct anon_vma *anon_vma = NULL; + XA_STATE(xas, &folio->mapping->i_pages, folio->index); + struct folio *end_folio = folio_next(folio); + bool is_anon = folio_test_anon(folio); struct address_space *mapping = NULL; - int count, mapcount, extra_pins, ret; - bool mlocked; - unsigned long flags; - pgoff_t end; + struct anon_vma *anon_vma = NULL; + int old_order = folio_order(folio); + struct folio *new_folio, *next; + int nr_shmem_dropped = 0; + int remap_flags = 0; + int extra_pins, ret; + pgoff_t end = 0; + bool is_hzp; + + VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio); + VM_WARN_ON_ONCE_FOLIO(!folio_test_large(folio), folio); + + if (folio != page_folio(split_at) || folio != page_folio(lock_at)) + return -EINVAL; + + /* + * Folios that just got truncated cannot get split. Signal to the + * caller that there was a race. + * + * TODO: this will also currently refuse shmem folios that are in the + * swapcache. + */ + if (!is_anon && !folio->mapping) + return -EBUSY; + + if (new_order >= old_order) + return -EINVAL; - VM_BUG_ON_PAGE(is_huge_zero_page(page), page); - VM_BUG_ON_PAGE(!PageLocked(page), page); - VM_BUG_ON_PAGE(!PageCompound(page), page); + if (!folio_split_supported(folio, new_order, split_type, /* warn = */ true)) + return -EINVAL; + + is_hzp = is_huge_zero_folio(folio); + if (is_hzp) { + pr_warn_ratelimited("Called split_huge_page for huge zero page\n"); + return -EBUSY; + } - if (PageWriteback(page)) + if (folio_test_writeback(folio)) return -EBUSY; - if (PageAnon(head)) { + if (is_anon) { /* - * The caller does not necessarily hold an mmap_sem that would + * The caller does not necessarily hold an mmap_lock that would * prevent the anon_vma disappearing so we first we take a * reference to it and then lock the anon_vma for write. This - * is similar to page_lock_anon_vma_read except the write lock + * is similar to folio_lock_anon_vma_read except the write lock * is taken to serialise against parallel split or collapse * operations. */ - anon_vma = page_get_anon_vma(head); + anon_vma = folio_get_anon_vma(folio); if (!anon_vma) { ret = -EBUSY; goto out; } - end = -1; - mapping = NULL; anon_vma_lock_write(anon_vma); + mapping = NULL; } else { - mapping = head->mapping; + unsigned int min_order; + gfp_t gfp; + + mapping = folio->mapping; + min_order = mapping_min_folio_order(folio->mapping); + if (new_order < min_order) { + ret = -EINVAL; + goto out; + } - /* Truncated ? */ - if (!mapping) { + gfp = current_gfp_context(mapping_gfp_mask(mapping) & + GFP_RECLAIM_MASK); + + if (!filemap_release_folio(folio, gfp)) { ret = -EBUSY; goto out; } + if (split_type == SPLIT_TYPE_UNIFORM) { + xas_set_order(&xas, folio->index, new_order); + xas_split_alloc(&xas, folio, old_order, gfp); + if (xas_error(&xas)) { + ret = xas_error(&xas); + goto out; + } + } + anon_vma = NULL; i_mmap_lock_read(mapping); /* - *__split_huge_page() may need to trim off pages beyond EOF: - * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, - * which cannot be nested inside the page tree lock. So note - * end now: i_size itself may be changed at any moment, but - * head page lock is good enough to serialize the trimming. + *__split_unmapped_folio() may need to trim off pages beyond + * EOF: but on 32-bit, i_size_read() takes an irq-unsafe + * seqlock, which cannot be nested inside the page tree lock. + * So note end now: i_size itself may be changed at any moment, + * but folio lock is good enough to serialize the trimming. */ end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); + if (shmem_mapping(mapping)) + end = shmem_fallocend(mapping->host, end); } /* - * Racy check if we can split the page, before unmap_page() will + * Racy check if we can split the page, before unmap_folio() will * split PMDs */ - if (!can_split_huge_page(head, &extra_pins)) { - ret = -EBUSY; + if (!can_split_folio(folio, 1, &extra_pins)) { + ret = -EAGAIN; goto out_unlock; } - mlocked = PageMlocked(page); - unmap_page(head); - VM_BUG_ON_PAGE(compound_mapcount(head), head); - - /* Make sure the page is not on per-CPU pagevec as it takes pin */ - if (mlocked) - lru_add_drain(); - - /* prevent PageLRU to go away from under us, and freeze lru stats */ - spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags); + unmap_folio(folio); + /* block interrupt reentry in xa_lock and spinlock */ + local_irq_disable(); if (mapping) { - XA_STATE(xas, &mapping->i_pages, page_index(head)); - /* - * Check if the head page is present in page cache. - * We assume all tail are present too, if head is there. + * Check if the folio is present in page cache. + * We assume all tail are present too, if folio is there. */ - xa_lock(&mapping->i_pages); - if (xas_load(&xas) != head) + xas_lock(&xas); + xas_reset(&xas); + if (xas_load(&xas) != folio) { + ret = -EAGAIN; goto fail; + } } - /* Prevent deferred_split_scan() touching ->_refcount */ - spin_lock(&pgdata->split_queue_lock); - count = page_count(head); - mapcount = total_mapcount(head); - if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { - if (!list_empty(page_deferred_list(head))) { - pgdata->split_queue_len--; - list_del(page_deferred_list(head)); - } - if (mapping) - __dec_node_page_state(page, NR_SHMEM_THPS); - spin_unlock(&pgdata->split_queue_lock); - __split_huge_page(page, list, end, flags); - if (PageSwapCache(head)) { - swp_entry_t entry = { .val = page_private(head) }; - - ret = split_swap_cluster(entry); - } else - ret = 0; - } else { - if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { - pr_alert("total_mapcount: %u, page_count(): %u\n", - mapcount, count); - if (PageTail(page)) - dump_page(head, NULL); - dump_page(page, "total_mapcount(head) > 0"); - BUG(); - } - spin_unlock(&pgdata->split_queue_lock); -fail: if (mapping) - xa_unlock(&mapping->i_pages); - spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags); - remap_page(head); - ret = -EBUSY; + ret = __folio_freeze_and_split_unmapped(folio, new_order, split_at, &xas, mapping, + true, list, split_type, end, &nr_shmem_dropped, + extra_pins); +fail: + if (mapping) + xas_unlock(&xas); + + local_irq_enable(); + + if (nr_shmem_dropped) + shmem_uncharge(mapping->host, nr_shmem_dropped); + + if (!ret && is_anon && !folio_is_device_private(folio)) + remap_flags = RMP_USE_SHARED_ZEROPAGE; + + remap_page(folio, 1 << old_order, remap_flags); + + /* + * Unlock all after-split folios except the one containing + * @lock_at page. If @folio is not split, it will be kept locked. + */ + for (new_folio = folio; new_folio != end_folio; new_folio = next) { + next = folio_next(new_folio); + if (new_folio == page_folio(lock_at)) + continue; + + folio_unlock(new_folio); + /* + * Subpages may be freed if there wasn't any mapping + * like if add_to_swap() is running on a lru page that + * had its mapping zapped. And freeing these pages + * requires taking the lru_lock so we do the put_page + * of the tail pages after the split is complete. + */ + free_folio_and_swap_cache(new_folio); } out_unlock: @@ -2741,218 +4094,870 @@ out_unlock: if (mapping) i_mmap_unlock_read(mapping); out: - count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); + xas_destroy(&xas); + if (old_order == HPAGE_PMD_ORDER) + count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); + count_mthp_stat(old_order, !ret ? MTHP_STAT_SPLIT : MTHP_STAT_SPLIT_FAILED); return ret; } -void free_transhuge_page(struct page *page) +/** + * folio_split_unmapped() - split a large anon folio that is already unmapped + * @folio: folio to split + * @new_order: the order of folios after split + * + * This function is a helper for splitting folios that have already been + * unmapped. The use case is that the device or the CPU can refuse to migrate + * THP pages in the middle of migration, due to allocation issues on either + * side. + * + * anon_vma_lock is not required to be held, mmap_read_lock() or + * mmap_write_lock() should be held. @folio is expected to be locked by the + * caller. device-private and non device-private folios are supported along + * with folios that are in the swapcache. @folio should also be unmapped and + * isolated from LRU (if applicable) + * + * Upon return, the folio is not remapped, split folios are not added to LRU, + * free_folio_and_swap_cache() is not called, and new folios remain locked. + * + * Return: 0 on success, -EAGAIN if the folio cannot be split (e.g., due to + * insufficient reference count or extra pins). + */ +int folio_split_unmapped(struct folio *folio, unsigned int new_order) { - struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); - unsigned long flags; + int extra_pins, ret = 0; + + VM_WARN_ON_ONCE_FOLIO(folio_mapped(folio), folio); + VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio); + VM_WARN_ON_ONCE_FOLIO(!folio_test_large(folio), folio); + VM_WARN_ON_ONCE_FOLIO(!folio_test_anon(folio), folio); + + if (!can_split_folio(folio, 1, &extra_pins)) + return -EAGAIN; + + local_irq_disable(); + ret = __folio_freeze_and_split_unmapped(folio, new_order, &folio->page, NULL, + NULL, false, NULL, SPLIT_TYPE_UNIFORM, + 0, NULL, extra_pins); + local_irq_enable(); + return ret; +} + +/* + * This function splits a large folio into smaller folios of order @new_order. + * @page can point to any page of the large folio to split. The split operation + * does not change the position of @page. + * + * Prerequisites: + * + * 1) The caller must hold a reference on the @page's owning folio, also known + * as the large folio. + * + * 2) The large folio must be locked. + * + * 3) The folio must not be pinned. Any unexpected folio references, including + * GUP pins, will result in the folio not getting split; instead, the caller + * will receive an -EAGAIN. + * + * 4) @new_order > 1, usually. Splitting to order-1 anonymous folios is not + * supported for non-file-backed folios, because folio->_deferred_list, which + * is used by partially mapped folios, is stored in subpage 2, but an order-1 + * folio only has subpages 0 and 1. File-backed order-1 folios are supported, + * since they do not use _deferred_list. + * + * After splitting, the caller's folio reference will be transferred to @page, + * resulting in a raised refcount of @page after this call. The other pages may + * be freed if they are not mapped. + * + * If @list is null, tail pages will be added to LRU list, otherwise, to @list. + * + * Pages in @new_order will inherit the mapping, flags, and so on from the + * huge page. + * + * Returns 0 if the huge page was split successfully. + * + * Returns -EAGAIN if the folio has unexpected reference (e.g., GUP) or if + * the folio was concurrently removed from the page cache. + * + * Returns -EBUSY when trying to split the huge zeropage, if the folio is + * under writeback, if fs-specific folio metadata cannot currently be + * released, or if some unexpected race happened (e.g., anon VMA disappeared, + * truncation). + * + * Callers should ensure that the order respects the address space mapping + * min-order if one is set for non-anonymous folios. + * + * Returns -EINVAL when trying to split to an order that is incompatible + * with the folio. Splitting to order 0 is compatible with all folios. + */ +int __split_huge_page_to_list_to_order(struct page *page, struct list_head *list, + unsigned int new_order) +{ + struct folio *folio = page_folio(page); + + return __folio_split(folio, new_order, &folio->page, page, list, + SPLIT_TYPE_UNIFORM); +} + +/** + * folio_split() - split a folio at @split_at to a @new_order folio + * @folio: folio to split + * @new_order: the order of the new folio + * @split_at: a page within the new folio + * @list: after-split folios are added to @list if not null, otherwise to LRU + * list + * + * It has the same prerequisites and returns as + * split_huge_page_to_list_to_order(). + * + * Split a folio at @split_at to a new_order folio, leave the + * remaining subpages of the original folio as large as possible. For example, + * in the case of splitting an order-9 folio at its third order-3 subpages to + * an order-3 folio, there are 2^(9-3)=64 order-3 subpages in the order-9 folio. + * After the split, there will be a group of folios with different orders and + * the new folio containing @split_at is marked in bracket: + * [order-4, {order-3}, order-3, order-5, order-6, order-7, order-8]. + * + * After split, folio is left locked for caller. + * + * Return: 0 - successful, <0 - failed (if -ENOMEM is returned, @folio might be + * split but not to @new_order, the caller needs to check) + */ +int folio_split(struct folio *folio, unsigned int new_order, + struct page *split_at, struct list_head *list) +{ + return __folio_split(folio, new_order, split_at, &folio->page, list, + SPLIT_TYPE_NON_UNIFORM); +} - spin_lock_irqsave(&pgdata->split_queue_lock, flags); - if (!list_empty(page_deferred_list(page))) { - pgdata->split_queue_len--; - list_del(page_deferred_list(page)); +int min_order_for_split(struct folio *folio) +{ + if (folio_test_anon(folio)) + return 0; + + if (!folio->mapping) { + if (folio_test_pmd_mappable(folio)) + count_vm_event(THP_SPLIT_PAGE_FAILED); + return -EBUSY; } - spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); - free_compound_page(page); + + return mapping_min_folio_order(folio->mapping); } -void deferred_split_huge_page(struct page *page) +int split_folio_to_list(struct folio *folio, struct list_head *list) +{ + return split_huge_page_to_list_to_order(&folio->page, list, 0); +} + +/* + * __folio_unqueue_deferred_split() is not to be called directly: + * the folio_unqueue_deferred_split() inline wrapper in mm/internal.h + * limits its calls to those folios which may have a _deferred_list for + * queueing THP splits, and that list is (racily observed to be) non-empty. + * + * It is unsafe to call folio_unqueue_deferred_split() until folio refcount is + * zero: because even when split_queue_lock is held, a non-empty _deferred_list + * might be in use on deferred_split_scan()'s unlocked on-stack list. + * + * If memory cgroups are enabled, split_queue_lock is in the mem_cgroup: it is + * therefore important to unqueue deferred split before changing folio memcg. + */ +bool __folio_unqueue_deferred_split(struct folio *folio) { - struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); + struct deferred_split *ds_queue; unsigned long flags; + bool unqueued = false; + + WARN_ON_ONCE(folio_ref_count(folio)); + WARN_ON_ONCE(!mem_cgroup_disabled() && !folio_memcg_charged(folio)); + + ds_queue = folio_split_queue_lock_irqsave(folio, &flags); + if (!list_empty(&folio->_deferred_list)) { + ds_queue->split_queue_len--; + if (folio_test_partially_mapped(folio)) { + folio_clear_partially_mapped(folio); + mod_mthp_stat(folio_order(folio), + MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); + } + list_del_init(&folio->_deferred_list); + unqueued = true; + } + split_queue_unlock_irqrestore(ds_queue, flags); + + return unqueued; /* useful for debug warnings */ +} + +/* partially_mapped=false won't clear PG_partially_mapped folio flag */ +void deferred_split_folio(struct folio *folio, bool partially_mapped) +{ + struct deferred_split *ds_queue; + unsigned long flags; + + /* + * Order 1 folios have no space for a deferred list, but we also + * won't waste much memory by not adding them to the deferred list. + */ + if (folio_order(folio) <= 1) + return; - VM_BUG_ON_PAGE(!PageTransHuge(page), page); + if (!partially_mapped && !split_underused_thp) + return; - spin_lock_irqsave(&pgdata->split_queue_lock, flags); - if (list_empty(page_deferred_list(page))) { - count_vm_event(THP_DEFERRED_SPLIT_PAGE); - list_add_tail(page_deferred_list(page), &pgdata->split_queue); - pgdata->split_queue_len++; + /* + * Exclude swapcache: originally to avoid a corrupt deferred split + * queue. Nowadays that is fully prevented by memcg1_swapout(); + * but if page reclaim is already handling the same folio, it is + * unnecessary to handle it again in the shrinker, so excluding + * swapcache here may still be a useful optimization. + */ + if (folio_test_swapcache(folio)) + return; + + ds_queue = folio_split_queue_lock_irqsave(folio, &flags); + if (partially_mapped) { + if (!folio_test_partially_mapped(folio)) { + folio_set_partially_mapped(folio); + if (folio_test_pmd_mappable(folio)) + count_vm_event(THP_DEFERRED_SPLIT_PAGE); + count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED); + mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, 1); + + } + } else { + /* partially mapped folios cannot become non-partially mapped */ + VM_WARN_ON_FOLIO(folio_test_partially_mapped(folio), folio); + } + if (list_empty(&folio->_deferred_list)) { + struct mem_cgroup *memcg; + + memcg = folio_split_queue_memcg(folio, ds_queue); + list_add_tail(&folio->_deferred_list, &ds_queue->split_queue); + ds_queue->split_queue_len++; + if (memcg) + set_shrinker_bit(memcg, folio_nid(folio), + shrinker_id(deferred_split_shrinker)); } - spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); + split_queue_unlock_irqrestore(ds_queue, flags); } static unsigned long deferred_split_count(struct shrinker *shrink, struct shrink_control *sc) { struct pglist_data *pgdata = NODE_DATA(sc->nid); - return READ_ONCE(pgdata->split_queue_len); + struct deferred_split *ds_queue = &pgdata->deferred_split_queue; + +#ifdef CONFIG_MEMCG + if (sc->memcg) + ds_queue = &sc->memcg->deferred_split_queue; +#endif + return READ_ONCE(ds_queue->split_queue_len); +} + +static bool thp_underused(struct folio *folio) +{ + int num_zero_pages = 0, num_filled_pages = 0; + int i; + + if (khugepaged_max_ptes_none == HPAGE_PMD_NR - 1) + return false; + + if (folio_contain_hwpoisoned_page(folio)) + return false; + + for (i = 0; i < folio_nr_pages(folio); i++) { + if (pages_identical(folio_page(folio, i), ZERO_PAGE(0))) { + if (++num_zero_pages > khugepaged_max_ptes_none) + return true; + } else { + /* + * Another path for early exit once the number + * of non-zero filled pages exceeds threshold. + */ + if (++num_filled_pages >= HPAGE_PMD_NR - khugepaged_max_ptes_none) + return false; + } + } + return false; } static unsigned long deferred_split_scan(struct shrinker *shrink, struct shrink_control *sc) { - struct pglist_data *pgdata = NODE_DATA(sc->nid); + struct deferred_split *ds_queue; unsigned long flags; - LIST_HEAD(list), *pos, *next; - struct page *page; - int split = 0; + struct folio *folio, *next; + int split = 0, i; + struct folio_batch fbatch; + + folio_batch_init(&fbatch); - spin_lock_irqsave(&pgdata->split_queue_lock, flags); +retry: + ds_queue = split_queue_lock_irqsave(sc->nid, sc->memcg, &flags); /* Take pin on all head pages to avoid freeing them under us */ - list_for_each_safe(pos, next, &pgdata->split_queue) { - page = list_entry((void *)pos, struct page, mapping); - page = compound_head(page); - if (get_page_unless_zero(page)) { - list_move(page_deferred_list(page), &list); - } else { - /* We lost race with put_compound_page() */ - list_del_init(page_deferred_list(page)); - pgdata->split_queue_len--; + list_for_each_entry_safe(folio, next, &ds_queue->split_queue, + _deferred_list) { + if (folio_try_get(folio)) { + folio_batch_add(&fbatch, folio); + } else if (folio_test_partially_mapped(folio)) { + /* We lost race with folio_put() */ + folio_clear_partially_mapped(folio); + mod_mthp_stat(folio_order(folio), + MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); } + list_del_init(&folio->_deferred_list); + ds_queue->split_queue_len--; if (!--sc->nr_to_scan) break; + if (!folio_batch_space(&fbatch)) + break; } - spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); + split_queue_unlock_irqrestore(ds_queue, flags); - list_for_each_safe(pos, next, &list) { - page = list_entry((void *)pos, struct page, mapping); - if (!trylock_page(page)) + for (i = 0; i < folio_batch_count(&fbatch); i++) { + bool did_split = false; + bool underused = false; + struct deferred_split *fqueue; + + folio = fbatch.folios[i]; + if (!folio_test_partially_mapped(folio)) { + /* + * See try_to_map_unused_to_zeropage(): we cannot + * optimize zero-filled pages after splitting an + * mlocked folio. + */ + if (folio_test_mlocked(folio)) + goto next; + underused = thp_underused(folio); + if (!underused) + goto next; + } + if (!folio_trylock(folio)) goto next; - /* split_huge_page() removes page from list on success */ - if (!split_huge_page(page)) + if (!split_folio(folio)) { + did_split = true; + if (underused) + count_vm_event(THP_UNDERUSED_SPLIT_PAGE); split++; - unlock_page(page); + } + folio_unlock(folio); next: - put_page(page); + if (did_split || !folio_test_partially_mapped(folio)) + continue; + /* + * Only add back to the queue if folio is partially mapped. + * If thp_underused returns false, or if split_folio fails + * in the case it was underused, then consider it used and + * don't add it back to split_queue. + */ + fqueue = folio_split_queue_lock_irqsave(folio, &flags); + if (list_empty(&folio->_deferred_list)) { + list_add_tail(&folio->_deferred_list, &fqueue->split_queue); + fqueue->split_queue_len++; + } + split_queue_unlock_irqrestore(fqueue, flags); } + folios_put(&fbatch); - spin_lock_irqsave(&pgdata->split_queue_lock, flags); - list_splice_tail(&list, &pgdata->split_queue); - spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); + if (sc->nr_to_scan && !list_empty(&ds_queue->split_queue)) { + cond_resched(); + goto retry; + } /* * Stop shrinker if we didn't split any page, but the queue is empty. * This can happen if pages were freed under us. */ - if (!split && list_empty(&pgdata->split_queue)) + if (!split && list_empty(&ds_queue->split_queue)) return SHRINK_STOP; return split; } -static struct shrinker deferred_split_shrinker = { - .count_objects = deferred_split_count, - .scan_objects = deferred_split_scan, - .seeks = DEFAULT_SEEKS, - .flags = SHRINKER_NUMA_AWARE, -}; +#ifdef CONFIG_MEMCG +void reparent_deferred_split_queue(struct mem_cgroup *memcg) +{ + struct mem_cgroup *parent = parent_mem_cgroup(memcg); + struct deferred_split *ds_queue = &memcg->deferred_split_queue; + struct deferred_split *parent_ds_queue = &parent->deferred_split_queue; + int nid; + + spin_lock_irq(&ds_queue->split_queue_lock); + spin_lock_nested(&parent_ds_queue->split_queue_lock, SINGLE_DEPTH_NESTING); + + if (!ds_queue->split_queue_len) + goto unlock; + + list_splice_tail_init(&ds_queue->split_queue, &parent_ds_queue->split_queue); + parent_ds_queue->split_queue_len += ds_queue->split_queue_len; + ds_queue->split_queue_len = 0; + + for_each_node(nid) + set_shrinker_bit(parent, nid, shrinker_id(deferred_split_shrinker)); + +unlock: + spin_unlock(&parent_ds_queue->split_queue_lock); + spin_unlock_irq(&ds_queue->split_queue_lock); +} +#endif #ifdef CONFIG_DEBUG_FS -static int split_huge_pages_set(void *data, u64 val) +static void split_huge_pages_all(void) { struct zone *zone; struct page *page; + struct folio *folio; unsigned long pfn, max_zone_pfn; unsigned long total = 0, split = 0; - if (val != 1) - return -EINVAL; - - for_each_populated_zone(zone) { + pr_debug("Split all THPs\n"); + for_each_zone(zone) { + if (!managed_zone(zone)) + continue; max_zone_pfn = zone_end_pfn(zone); for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { - if (!pfn_valid(pfn)) - continue; + int nr_pages; - page = pfn_to_page(pfn); - if (!get_page_unless_zero(page)) + page = pfn_to_online_page(pfn); + if (!page || PageTail(page)) + continue; + folio = page_folio(page); + if (!folio_try_get(folio)) continue; - if (zone != page_zone(page)) + if (unlikely(page_folio(page) != folio)) goto next; - if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) + if (zone != folio_zone(folio)) + goto next; + + if (!folio_test_large(folio) + || folio_test_hugetlb(folio) + || !folio_test_lru(folio)) goto next; total++; - lock_page(page); - if (!split_huge_page(page)) + folio_lock(folio); + nr_pages = folio_nr_pages(folio); + if (!split_folio(folio)) split++; - unlock_page(page); + pfn += nr_pages - 1; + folio_unlock(folio); next: - put_page(page); + folio_put(folio); + cond_resched(); } } - pr_info("%lu of %lu THP split\n", split, total); + pr_debug("%lu of %lu THP split\n", split, total); +} - return 0; +static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) +{ + return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || + is_vm_hugetlb_page(vma); } -DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, - "%llu\n"); -static int __init split_huge_pages_debugfs(void) +static int split_huge_pages_pid(int pid, unsigned long vaddr_start, + unsigned long vaddr_end, unsigned int new_order, + long in_folio_offset) +{ + int ret = 0; + struct task_struct *task; + struct mm_struct *mm; + unsigned long total = 0, split = 0; + unsigned long addr; + + vaddr_start &= PAGE_MASK; + vaddr_end &= PAGE_MASK; + + task = find_get_task_by_vpid(pid); + if (!task) { + ret = -ESRCH; + goto out; + } + + /* Find the mm_struct */ + mm = get_task_mm(task); + put_task_struct(task); + + if (!mm) { + ret = -EINVAL; + goto out; + } + + pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx], new_order: %u, in_folio_offset: %ld\n", + pid, vaddr_start, vaddr_end, new_order, in_folio_offset); + + mmap_read_lock(mm); + /* + * always increase addr by PAGE_SIZE, since we could have a PTE page + * table filled with PTE-mapped THPs, each of which is distinct. + */ + for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { + struct vm_area_struct *vma = vma_lookup(mm, addr); + struct folio_walk fw; + struct folio *folio; + struct address_space *mapping; + unsigned int target_order = new_order; + + if (!vma) + break; + + /* skip special VMA and hugetlb VMA */ + if (vma_not_suitable_for_thp_split(vma)) { + addr = vma->vm_end; + continue; + } + + folio = folio_walk_start(&fw, vma, addr, 0); + if (!folio) + continue; + + if (!is_transparent_hugepage(folio)) + goto next; + + if (!folio_test_anon(folio)) { + mapping = folio->mapping; + target_order = max(new_order, + mapping_min_folio_order(mapping)); + } + + if (target_order >= folio_order(folio)) + goto next; + + total++; + /* + * For folios with private, split_huge_page_to_list_to_order() + * will try to drop it before split and then check if the folio + * can be split or not. So skip the check here. + */ + if (!folio_test_private(folio) && + !can_split_folio(folio, 0, NULL)) + goto next; + + if (!folio_trylock(folio)) + goto next; + folio_get(folio); + folio_walk_end(&fw, vma); + + if (!folio_test_anon(folio) && folio->mapping != mapping) + goto unlock; + + if (in_folio_offset < 0 || + in_folio_offset >= folio_nr_pages(folio)) { + if (!split_folio_to_order(folio, target_order)) + split++; + } else { + struct page *split_at = folio_page(folio, + in_folio_offset); + if (!folio_split(folio, target_order, split_at, NULL)) + split++; + } + +unlock: + + folio_unlock(folio); + folio_put(folio); + + cond_resched(); + continue; +next: + folio_walk_end(&fw, vma); + cond_resched(); + } + mmap_read_unlock(mm); + mmput(mm); + + pr_debug("%lu of %lu THP split\n", split, total); + +out: + return ret; +} + +static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, + pgoff_t off_end, unsigned int new_order, + long in_folio_offset) +{ + struct filename *file; + struct file *candidate; + struct address_space *mapping; + int ret = -EINVAL; + pgoff_t index; + int nr_pages = 1; + unsigned long total = 0, split = 0; + unsigned int min_order; + unsigned int target_order; + + file = getname_kernel(file_path); + if (IS_ERR(file)) + return ret; + + candidate = file_open_name(file, O_RDONLY, 0); + if (IS_ERR(candidate)) + goto out; + + pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx], new_order: %u, in_folio_offset: %ld\n", + file_path, off_start, off_end, new_order, in_folio_offset); + + mapping = candidate->f_mapping; + min_order = mapping_min_folio_order(mapping); + target_order = max(new_order, min_order); + + for (index = off_start; index < off_end; index += nr_pages) { + struct folio *folio = filemap_get_folio(mapping, index); + + nr_pages = 1; + if (IS_ERR(folio)) + continue; + + if (!folio_test_large(folio)) + goto next; + + total++; + nr_pages = folio_nr_pages(folio); + + if (target_order >= folio_order(folio)) + goto next; + + if (!folio_trylock(folio)) + goto next; + + if (folio->mapping != mapping) + goto unlock; + + if (in_folio_offset < 0 || in_folio_offset >= nr_pages) { + if (!split_folio_to_order(folio, target_order)) + split++; + } else { + struct page *split_at = folio_page(folio, + in_folio_offset); + if (!folio_split(folio, target_order, split_at, NULL)) + split++; + } + +unlock: + folio_unlock(folio); +next: + folio_put(folio); + cond_resched(); + } + + filp_close(candidate, NULL); + ret = 0; + + pr_debug("%lu of %lu file-backed THP split\n", split, total); +out: + putname(file); + return ret; +} + +#define MAX_INPUT_BUF_SZ 255 + +static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppops) { - void *ret; + static DEFINE_MUTEX(split_debug_mutex); + ssize_t ret; + /* + * hold pid, start_vaddr, end_vaddr, new_order or + * file_path, off_start, off_end, new_order + */ + char input_buf[MAX_INPUT_BUF_SZ]; + int pid; + unsigned long vaddr_start, vaddr_end; + unsigned int new_order = 0; + long in_folio_offset = -1; + + ret = mutex_lock_interruptible(&split_debug_mutex); + if (ret) + return ret; + + ret = -EFAULT; - ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL, - &split_huge_pages_fops); + memset(input_buf, 0, MAX_INPUT_BUF_SZ); + if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) + goto out; + + input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; + + if (input_buf[0] == '/') { + char *tok; + char *tok_buf = input_buf; + char file_path[MAX_INPUT_BUF_SZ]; + pgoff_t off_start = 0, off_end = 0; + size_t input_len = strlen(input_buf); + + tok = strsep(&tok_buf, ","); + if (tok && tok_buf) { + strscpy(file_path, tok); + } else { + ret = -EINVAL; + goto out; + } + + ret = sscanf(tok_buf, "0x%lx,0x%lx,%d,%ld", &off_start, &off_end, + &new_order, &in_folio_offset); + if (ret != 2 && ret != 3 && ret != 4) { + ret = -EINVAL; + goto out; + } + ret = split_huge_pages_in_file(file_path, off_start, off_end, + new_order, in_folio_offset); + if (!ret) + ret = input_len; + + goto out; + } + + ret = sscanf(input_buf, "%d,0x%lx,0x%lx,%d,%ld", &pid, &vaddr_start, + &vaddr_end, &new_order, &in_folio_offset); + if (ret == 1 && pid == 1) { + split_huge_pages_all(); + ret = strlen(input_buf); + goto out; + } else if (ret != 3 && ret != 4 && ret != 5) { + ret = -EINVAL; + goto out; + } + + ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end, new_order, + in_folio_offset); if (!ret) - pr_warn("Failed to create split_huge_pages in debugfs"); + ret = strlen(input_buf); +out: + mutex_unlock(&split_debug_mutex); + return ret; + +} + +static const struct file_operations split_huge_pages_fops = { + .owner = THIS_MODULE, + .write = split_huge_pages_write, +}; + +static int __init split_huge_pages_debugfs(void) +{ + debugfs_create_file("split_huge_pages", 0200, NULL, NULL, + &split_huge_pages_fops); return 0; } late_initcall(split_huge_pages_debugfs); #endif #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION -void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, +int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, struct page *page) { + struct folio *folio = page_folio(page); struct vm_area_struct *vma = pvmw->vma; struct mm_struct *mm = vma->vm_mm; unsigned long address = pvmw->address; + bool anon_exclusive; pmd_t pmdval; swp_entry_t entry; pmd_t pmdswp; if (!(pvmw->pmd && !pvmw->pte)) - return; + return 0; flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); - pmdval = *pvmw->pmd; - pmdp_invalidate(vma, address, pvmw->pmd); + if (unlikely(!pmd_present(*pvmw->pmd))) + pmdval = pmdp_huge_get_and_clear(vma->vm_mm, address, pvmw->pmd); + else + pmdval = pmdp_invalidate(vma, address, pvmw->pmd); + + /* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */ + anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page); + if (anon_exclusive && folio_try_share_anon_rmap_pmd(folio, page)) { + set_pmd_at(mm, address, pvmw->pmd, pmdval); + return -EBUSY; + } + if (pmd_dirty(pmdval)) - set_page_dirty(page); - entry = make_migration_entry(page, pmd_write(pmdval)); + folio_mark_dirty(folio); + if (pmd_write(pmdval)) + entry = make_writable_migration_entry(page_to_pfn(page)); + else if (anon_exclusive) + entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); + else + entry = make_readable_migration_entry(page_to_pfn(page)); + if (pmd_young(pmdval)) + entry = make_migration_entry_young(entry); + if (pmd_dirty(pmdval)) + entry = make_migration_entry_dirty(entry); pmdswp = swp_entry_to_pmd(entry); if (pmd_soft_dirty(pmdval)) pmdswp = pmd_swp_mksoft_dirty(pmdswp); + if (pmd_uffd_wp(pmdval)) + pmdswp = pmd_swp_mkuffd_wp(pmdswp); set_pmd_at(mm, address, pvmw->pmd, pmdswp); - page_remove_rmap(page, true); - put_page(page); + folio_remove_rmap_pmd(folio, page, vma); + folio_put(folio); + trace_set_migration_pmd(address, pmd_val(pmdswp)); + + return 0; } void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) { + struct folio *folio = page_folio(new); struct vm_area_struct *vma = pvmw->vma; struct mm_struct *mm = vma->vm_mm; unsigned long address = pvmw->address; - unsigned long mmun_start = address & HPAGE_PMD_MASK; + unsigned long haddr = address & HPAGE_PMD_MASK; pmd_t pmde; - swp_entry_t entry; + softleaf_t entry; if (!(pvmw->pmd && !pvmw->pte)) return; - entry = pmd_to_swp_entry(*pvmw->pmd); - get_page(new); - pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); + entry = softleaf_from_pmd(*pvmw->pmd); + folio_get(folio); + pmde = folio_mk_pmd(folio, READ_ONCE(vma->vm_page_prot)); + if (pmd_swp_soft_dirty(*pvmw->pmd)) pmde = pmd_mksoft_dirty(pmde); - if (is_write_migration_entry(entry)) - pmde = maybe_pmd_mkwrite(pmde, vma); + if (softleaf_is_migration_write(entry)) + pmde = pmd_mkwrite(pmde, vma); + if (pmd_swp_uffd_wp(*pvmw->pmd)) + pmde = pmd_mkuffd_wp(pmde); + if (!softleaf_is_migration_young(entry)) + pmde = pmd_mkold(pmde); + /* NOTE: this may contain setting soft-dirty on some archs */ + if (folio_test_dirty(folio) && softleaf_is_migration_dirty(entry)) + pmde = pmd_mkdirty(pmde); + + if (folio_is_device_private(folio)) { + swp_entry_t entry; - flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE); - if (PageAnon(new)) - page_add_anon_rmap(new, vma, mmun_start, true); - else - page_add_file_rmap(new, true); - set_pmd_at(mm, mmun_start, pvmw->pmd, pmde); - if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new)) - mlock_vma_page(new); + if (pmd_write(pmde)) + entry = make_writable_device_private_entry( + page_to_pfn(new)); + else + entry = make_readable_device_private_entry( + page_to_pfn(new)); + pmde = swp_entry_to_pmd(entry); + + if (pmd_swp_soft_dirty(*pvmw->pmd)) + pmde = pmd_swp_mksoft_dirty(pmde); + if (pmd_swp_uffd_wp(*pvmw->pmd)) + pmde = pmd_swp_mkuffd_wp(pmde); + } + + if (folio_test_anon(folio)) { + rmap_t rmap_flags = RMAP_NONE; + + if (!softleaf_is_migration_read(entry)) + rmap_flags |= RMAP_EXCLUSIVE; + + folio_add_anon_rmap_pmd(folio, new, vma, haddr, rmap_flags); + } else { + folio_add_file_rmap_pmd(folio, new, vma); + } + VM_BUG_ON(pmd_write(pmde) && folio_test_anon(folio) && !PageAnonExclusive(new)); + set_pmd_at(mm, haddr, pvmw->pmd, pmde); + + /* No need to invalidate - it was non-present before */ update_mmu_cache_pmd(vma, address, pvmw->pmd); + trace_remove_migration_pmd(address, pmd_val(pmde)); } #endif |