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authorVlastimil Babka <vbabka@suse.cz>2020-01-13 16:29:20 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-13 18:19:02 -0800
commit8e57f8acbbd121ecfb0c9dc13b8b030f86c6bd3b (patch)
tree91516d1faa0be5ed78a8919e0fc6a0b1da1d2a8d /mm
parent4a87e2a25dc27131c3cce5e94421622193305638 (diff)
mm, debug_pagealloc: don't rely on static keys too early
Commit 96a2b03f281d ("mm, debug_pagelloc: use static keys to enable debugging") has introduced a static key to reduce overhead when debug_pagealloc is compiled in but not enabled. It relied on the assumption that jump_label_init() is called before parse_early_param() as in start_kernel(), so when the "debug_pagealloc=on" option is parsed, it is safe to enable the static key. However, it turns out multiple architectures call parse_early_param() earlier from their setup_arch(). x86 also calls jump_label_init() even earlier, so no issue was found while testing the commit, but same is not true for e.g. ppc64 and s390 where the kernel would not boot with debug_pagealloc=on as found by our QA. To fix this without tricky changes to init code of multiple architectures, this patch partially reverts the static key conversion from 96a2b03f281d. Init-time and non-fastpath calls (such as in arch code) of debug_pagealloc_enabled() will again test a simple bool variable. Fastpath mm code is converted to a new debug_pagealloc_enabled_static() variant that relies on the static key, which is enabled in a well-defined point in mm_init() where it's guaranteed that jump_label_init() has been called, regardless of architecture. [sfr@canb.auug.org.au: export _debug_pagealloc_enabled_early] Link: http://lkml.kernel.org/r/20200106164944.063ac07b@canb.auug.org.au Link: http://lkml.kernel.org/r/20191219130612.23171-1-vbabka@suse.cz Fixes: 96a2b03f281d ("mm, debug_pagelloc: use static keys to enable debugging") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Qian Cai <cai@lca.pw> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c37
-rw-r--r--mm/slab.c4
-rw-r--r--mm/slub.c2
-rw-r--r--mm/vmalloc.c4
4 files changed, 18 insertions, 29 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 409be5ec7e2c..d047bf7d8fd4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -694,34 +694,27 @@ void prep_compound_page(struct page *page, unsigned int order)
#ifdef CONFIG_DEBUG_PAGEALLOC
unsigned int _debug_guardpage_minorder;
-#ifdef CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT
-DEFINE_STATIC_KEY_TRUE(_debug_pagealloc_enabled);
-#else
+bool _debug_pagealloc_enabled_early __read_mostly
+ = IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT);
+EXPORT_SYMBOL(_debug_pagealloc_enabled_early);
DEFINE_STATIC_KEY_FALSE(_debug_pagealloc_enabled);
-#endif
EXPORT_SYMBOL(_debug_pagealloc_enabled);
DEFINE_STATIC_KEY_FALSE(_debug_guardpage_enabled);
static int __init early_debug_pagealloc(char *buf)
{
- bool enable = false;
-
- if (kstrtobool(buf, &enable))
- return -EINVAL;
-
- if (enable)
- static_branch_enable(&_debug_pagealloc_enabled);
-
- return 0;
+ return kstrtobool(buf, &_debug_pagealloc_enabled_early);
}
early_param("debug_pagealloc", early_debug_pagealloc);
-static void init_debug_guardpage(void)
+void init_debug_pagealloc(void)
{
if (!debug_pagealloc_enabled())
return;
+ static_branch_enable(&_debug_pagealloc_enabled);
+
if (!debug_guardpage_minorder())
return;
@@ -1186,7 +1179,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
*/
arch_free_page(page, order);
- if (debug_pagealloc_enabled())
+ if (debug_pagealloc_enabled_static())
kernel_map_pages(page, 1 << order, 0);
kasan_free_nondeferred_pages(page, order);
@@ -1207,7 +1200,7 @@ static bool free_pcp_prepare(struct page *page)
static bool bulkfree_pcp_prepare(struct page *page)
{
- if (debug_pagealloc_enabled())
+ if (debug_pagealloc_enabled_static())
return free_pages_check(page);
else
return false;
@@ -1221,7 +1214,7 @@ static bool bulkfree_pcp_prepare(struct page *page)
*/
static bool free_pcp_prepare(struct page *page)
{
- if (debug_pagealloc_enabled())
+ if (debug_pagealloc_enabled_static())
return free_pages_prepare(page, 0, true);
else
return free_pages_prepare(page, 0, false);
@@ -1973,10 +1966,6 @@ void __init page_alloc_init_late(void)
for_each_populated_zone(zone)
set_zone_contiguous(zone);
-
-#ifdef CONFIG_DEBUG_PAGEALLOC
- init_debug_guardpage();
-#endif
}
#ifdef CONFIG_CMA
@@ -2106,7 +2095,7 @@ static inline bool free_pages_prezeroed(void)
*/
static inline bool check_pcp_refill(struct page *page)
{
- if (debug_pagealloc_enabled())
+ if (debug_pagealloc_enabled_static())
return check_new_page(page);
else
return false;
@@ -2128,7 +2117,7 @@ static inline bool check_pcp_refill(struct page *page)
}
static inline bool check_new_pcp(struct page *page)
{
- if (debug_pagealloc_enabled())
+ if (debug_pagealloc_enabled_static())
return check_new_page(page);
else
return false;
@@ -2155,7 +2144,7 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
set_page_refcounted(page);
arch_alloc_page(page, order);
- if (debug_pagealloc_enabled())
+ if (debug_pagealloc_enabled_static())
kernel_map_pages(page, 1 << order, 1);
kasan_alloc_pages(page, order);
kernel_poison_pages(page, 1 << order, 1);
diff --git a/mm/slab.c b/mm/slab.c
index f1e1840af533..a89633603b2d 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1416,7 +1416,7 @@ static void kmem_rcu_free(struct rcu_head *head)
#if DEBUG
static bool is_debug_pagealloc_cache(struct kmem_cache *cachep)
{
- if (debug_pagealloc_enabled() && OFF_SLAB(cachep) &&
+ if (debug_pagealloc_enabled_static() && OFF_SLAB(cachep) &&
(cachep->size % PAGE_SIZE) == 0)
return true;
@@ -2008,7 +2008,7 @@ int __kmem_cache_create(struct kmem_cache *cachep, slab_flags_t flags)
* to check size >= 256. It guarantees that all necessary small
* sized slab is initialized in current slab initialization sequence.
*/
- if (debug_pagealloc_enabled() && (flags & SLAB_POISON) &&
+ if (debug_pagealloc_enabled_static() && (flags & SLAB_POISON) &&
size >= 256 && cachep->object_size > cache_line_size()) {
if (size < PAGE_SIZE || size % PAGE_SIZE == 0) {
size_t tmp_size = ALIGN(size, PAGE_SIZE);
diff --git a/mm/slub.c b/mm/slub.c
index d11389710b12..8eafccf75940 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -288,7 +288,7 @@ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
unsigned long freepointer_addr;
void *p;
- if (!debug_pagealloc_enabled())
+ if (!debug_pagealloc_enabled_static())
return get_freepointer(s, object);
freepointer_addr = (unsigned long)object + s->offset;
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index e9681dc4aa75..b29ad17edcf5 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1383,7 +1383,7 @@ static void free_unmap_vmap_area(struct vmap_area *va)
{
flush_cache_vunmap(va->va_start, va->va_end);
unmap_vmap_area(va);
- if (debug_pagealloc_enabled())
+ if (debug_pagealloc_enabled_static())
flush_tlb_kernel_range(va->va_start, va->va_end);
free_vmap_area_noflush(va);
@@ -1681,7 +1681,7 @@ static void vb_free(const void *addr, unsigned long size)
vunmap_page_range((unsigned long)addr, (unsigned long)addr + size);
- if (debug_pagealloc_enabled())
+ if (debug_pagealloc_enabled_static())
flush_tlb_kernel_range((unsigned long)addr,
(unsigned long)addr + size);