The patch titled Subject: slub: track number of slabs irrespective of CONFIG_SLUB_DEBUG has been added to the -mm tree. Its filename is slub-track-number-of-slabs-irrespective-of-config_slub_debug.patch
This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/slub-track-number-of-slabs-irrespec... and later at http://ozlabs.org/~akpm/mmotm/broken-out/slub-track-number-of-slabs-irrespec...
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------------------------------------------------------ From: Shakeel Butt shakeelb@google.com Subject: slub: track number of slabs irrespective of CONFIG_SLUB_DEBUG
For !CONFIG_SLUB_DEBUG, SLUB does not maintain the number of slabs allocated per node for a kmem_cache. Thus, slabs_node() in __kmem_cache_empty(), __kmem_cache_shrink() and __kmem_cache_destroy() will always return 0 for such config. This is wrong and can cause issues for all users of these functions.
In fact in [1] Jason has reported a system crash while using SLUB without CONFIG_SLUB_DEBUG. The reason was the usage of slabs_node() by __kmem_cache_empty().
The right solution is to make slabs_node() work even for !CONFIG_SLUB_DEBUG. The commit 0f389ec63077 ("slub: No need for per node slab counters if !SLUB_DEBUG") had put the per node slab counter under CONFIG_SLUB_DEBUG because it was only read through sysfs API and the sysfs API was disabled on !CONFIG_SLUB_DEBUG. However the users of the per node slab counter assumed that it will work in the absence of CONFIG_SLUB_DEBUG. So, make the counter work for !CONFIG_SLUB_DEBUG.
Please note that f9e13c0a5a33 ("slab, slub: skip unnecessary kasan_cache_shutdown()") exposed this issue but it is present even before.
[1] http://lkml.kernel.org/r/CAHmME9rtoPwxUSnktxzKso14iuVCWT7BE_-_8PAC=pGw1iJnQg...
Link: http://lkml.kernel.org/r/20180620224147.23777-1-shakeelb@google.com Fixes: f9e13c0a5a33 ("slab, slub: skip unnecessary kasan_cache_shutdown()") Signed-off-by: Shakeel Butt shakeelb@google.com Suggested-by: David Rientjes rientjes@google.com Reported-by: Jason A . Donenfeld Jason@zx2c4.com Cc: Christoph Lameter cl@linux.com Cc: Pekka Enberg penberg@kernel.org Cc: Joonsoo Kim iamjoonsoo.kim@lge.com Cc: Andrey Ryabinin aryabinin@virtuozzo.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
mm/slab.h | 2 - mm/slub.c | 80 ++++++++++++++++++++++++---------------------------- 2 files changed, 38 insertions(+), 44 deletions(-)
diff -puN mm/slab.h~slub-track-number-of-slabs-irrespective-of-config_slub_debug mm/slab.h --- a/mm/slab.h~slub-track-number-of-slabs-irrespective-of-config_slub_debug +++ a/mm/slab.h @@ -473,8 +473,8 @@ struct kmem_cache_node { #ifdef CONFIG_SLUB unsigned long nr_partial; struct list_head partial; -#ifdef CONFIG_SLUB_DEBUG atomic_long_t nr_slabs; +#ifdef CONFIG_SLUB_DEBUG atomic_long_t total_objects; struct list_head full; #endif diff -puN mm/slub.c~slub-track-number-of-slabs-irrespective-of-config_slub_debug mm/slub.c --- a/mm/slub.c~slub-track-number-of-slabs-irrespective-of-config_slub_debug +++ a/mm/slub.c @@ -1030,42 +1030,6 @@ static void remove_full(struct kmem_cach list_del(&page->lru); }
-/* Tracking of the number of slabs for debugging purposes */ -static inline unsigned long slabs_node(struct kmem_cache *s, int node) -{ - struct kmem_cache_node *n = get_node(s, node); - - return atomic_long_read(&n->nr_slabs); -} - -static inline unsigned long node_nr_slabs(struct kmem_cache_node *n) -{ - return atomic_long_read(&n->nr_slabs); -} - -static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects) -{ - struct kmem_cache_node *n = get_node(s, node); - - /* - * May be called early in order to allocate a slab for the - * kmem_cache_node structure. Solve the chicken-egg - * dilemma by deferring the increment of the count during - * bootstrap (see early_kmem_cache_node_alloc). - */ - if (likely(n)) { - atomic_long_inc(&n->nr_slabs); - atomic_long_add(objects, &n->total_objects); - } -} -static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects) -{ - struct kmem_cache_node *n = get_node(s, node); - - atomic_long_dec(&n->nr_slabs); - atomic_long_sub(objects, &n->total_objects); -} - /* Object debug checks for alloc/free paths */ static void setup_object_debug(struct kmem_cache *s, struct page *page, void *object) @@ -1321,16 +1285,46 @@ slab_flags_t kmem_cache_flags(unsigned i
#define disable_higher_order_debug 0
+#endif /* CONFIG_SLUB_DEBUG */ + static inline unsigned long slabs_node(struct kmem_cache *s, int node) - { return 0; } +{ + struct kmem_cache_node *n = get_node(s, node); + + return atomic_long_read(&n->nr_slabs); +} + static inline unsigned long node_nr_slabs(struct kmem_cache_node *n) - { return 0; } -static inline void inc_slabs_node(struct kmem_cache *s, int node, - int objects) {} -static inline void dec_slabs_node(struct kmem_cache *s, int node, - int objects) {} +{ + return atomic_long_read(&n->nr_slabs); +}
-#endif /* CONFIG_SLUB_DEBUG */ +static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects) +{ + struct kmem_cache_node *n = get_node(s, node); + + /* + * May be called early in order to allocate a slab for the + * kmem_cache_node structure. Solve the chicken-egg + * dilemma by deferring the increment of the count during + * bootstrap (see early_kmem_cache_node_alloc). + */ + if (likely(n)) { + atomic_long_inc(&n->nr_slabs); +#ifdef CONFIG_SLUB_DEBUG + atomic_long_add(objects, &n->total_objects); +#endif + } +} +static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects) +{ + struct kmem_cache_node *n = get_node(s, node); + + atomic_long_dec(&n->nr_slabs); +#ifdef CONFIG_SLUB_DEBUG + atomic_long_sub(objects, &n->total_objects); +#endif +}
/* * Hooks for other subsystems that check memory allocations. In a typical _
Patches currently in -mm which might be from shakeelb@google.com are
slub-track-number-of-slabs-irrespective-of-config_slub_debug.patch slub-fix-__kmem_cache_empty-for-config_slub_debug.patch