diff options
| -rw-r--r-- | arch/s390/include/asm/pgalloc.h | 4 | ||||
| -rw-r--r-- | arch/s390/mm/pgalloc.c | 80 |
2 files changed, 72 insertions, 12 deletions
diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h index 17eb618f1348..89a9d5ef94f8 100644 --- a/arch/s390/include/asm/pgalloc.h +++ b/arch/s390/include/asm/pgalloc.h @@ -143,6 +143,10 @@ static inline void pmd_populate(struct mm_struct *mm, #define pte_free_kernel(mm, pte) page_table_free(mm, (unsigned long *) pte) #define pte_free(mm, pte) page_table_free(mm, (unsigned long *) pte) +/* arch use pte_free_defer() implementation in arch/s390/mm/pgalloc.c */ +#define pte_free_defer pte_free_defer +void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable); + void vmem_map_init(void); void *vmem_crst_alloc(unsigned long val); pte_t *vmem_pte_alloc(void); diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c index 66ab68db9842..d7374add7820 100644 --- a/arch/s390/mm/pgalloc.c +++ b/arch/s390/mm/pgalloc.c @@ -229,6 +229,15 @@ void page_table_free_pgste(struct page *page) * logic described above. Both AA bits are set to 1 to denote a 4KB-pgtable * while the PP bits are never used, nor such a page is added to or removed * from mm_context_t::pgtable_list. + * + * pte_free_defer() overrides those rules: it takes the page off pgtable_list, + * and prevents both 2K fragments from being reused. pte_free_defer() has to + * guarantee that its pgtable cannot be reused before the RCU grace period + * has elapsed (which page_table_free_rcu() does not actually guarantee). + * But for simplicity, because page->rcu_head overlays page->lru, and because + * the RCU callback might not be called before the mm_context_t has been freed, + * pte_free_defer() in this implementation prevents both fragments from being + * reused, and delays making the call to RCU until both fragments are freed. */ unsigned long *page_table_alloc(struct mm_struct *mm) { @@ -261,7 +270,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm) table += PTRS_PER_PTE; atomic_xor_bits(&page->_refcount, 0x01U << (bit + 24)); - list_del(&page->lru); + list_del_init(&page->lru); } } spin_unlock_bh(&mm->context.lock); @@ -281,6 +290,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm) table = (unsigned long *) page_to_virt(page); if (mm_alloc_pgste(mm)) { /* Return 4K page table with PGSTEs */ + INIT_LIST_HEAD(&page->lru); atomic_xor_bits(&page->_refcount, 0x03U << 24); memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); @@ -300,7 +310,9 @@ static void page_table_release_check(struct page *page, void *table, { char msg[128]; - if (!IS_ENABLED(CONFIG_DEBUG_VM) || !mask) + if (!IS_ENABLED(CONFIG_DEBUG_VM)) + return; + if (!mask && list_empty(&page->lru)) return; snprintf(msg, sizeof(msg), "Invalid pgtable %p release half 0x%02x mask 0x%02x", @@ -308,6 +320,15 @@ static void page_table_release_check(struct page *page, void *table, dump_page(page, msg); } +static void pte_free_now(struct rcu_head *head) +{ + struct page *page; + + page = container_of(head, struct page, rcu_head); + pgtable_pte_page_dtor(page); + __free_page(page); +} + void page_table_free(struct mm_struct *mm, unsigned long *table) { unsigned int mask, bit, half; @@ -325,10 +346,17 @@ void page_table_free(struct mm_struct *mm, unsigned long *table) */ mask = atomic_xor_bits(&page->_refcount, 0x11U << (bit + 24)); mask >>= 24; - if (mask & 0x03U) + if ((mask & 0x03U) && !PageActive(page)) { + /* + * Other half is allocated, and neither half has had + * its free deferred: add page to head of list, to make + * this freed half available for immediate reuse. + */ list_add(&page->lru, &mm->context.pgtable_list); - else - list_del(&page->lru); + } else { + /* If page is on list, now remove it. */ + list_del_init(&page->lru); + } spin_unlock_bh(&mm->context.lock); mask = atomic_xor_bits(&page->_refcount, 0x10U << (bit + 24)); mask >>= 24; @@ -342,8 +370,10 @@ void page_table_free(struct mm_struct *mm, unsigned long *table) } page_table_release_check(page, table, half, mask); - pgtable_pte_page_dtor(page); - __free_page(page); + if (TestClearPageActive(page)) + call_rcu(&page->rcu_head, pte_free_now); + else + pte_free_now(&page->rcu_head); } void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, @@ -370,10 +400,18 @@ void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, */ mask = atomic_xor_bits(&page->_refcount, 0x11U << (bit + 24)); mask >>= 24; - if (mask & 0x03U) + if ((mask & 0x03U) && !PageActive(page)) { + /* + * Other half is allocated, and neither half has had + * its free deferred: add page to end of list, to make + * this freed half available for reuse once its pending + * bit has been cleared by __tlb_remove_table(). + */ list_add_tail(&page->lru, &mm->context.pgtable_list); - else - list_del(&page->lru); + } else { + /* If page is on list, now remove it. */ + list_del_init(&page->lru); + } spin_unlock_bh(&mm->context.lock); table = (unsigned long *) ((unsigned long) table | (0x01U << bit)); tlb_remove_table(tlb, table); @@ -403,9 +441,27 @@ void __tlb_remove_table(void *_table) } page_table_release_check(page, table, half, mask); - pgtable_pte_page_dtor(page); - __free_page(page); + if (TestClearPageActive(page)) + call_rcu(&page->rcu_head, pte_free_now); + else + pte_free_now(&page->rcu_head); +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable) +{ + struct page *page; + + page = virt_to_page(pgtable); + SetPageActive(page); + page_table_free(mm, (unsigned long *)pgtable); + /* + * page_table_free() does not do the pgste gmap_unlink() which + * page_table_free_rcu() does: warn us if pgste ever reaches here. + */ + WARN_ON_ONCE(mm_has_pgste(mm)); } +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ /* * Base infrastructure required to generate basic asces, region, segment, |