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Donenfeld" Cc: David Rientjes , Christoph Lameter , Pekka Enberg , Joonsoo Kim , Andrew Morton , Andrey Ryabinin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Shakeel Butt , stable@vger.kernel.org Subject: [PATCH] slub: track number of slabs irrespective of CONFIG_SLUB_DEBUG Date: Wed, 20 Jun 2018 15:41:47 -0700 Message-Id: <20180620224147.23777-1-shakeelb@google.com> X-Mailer: git-send-email 2.18.0.rc1.244.gcf134e6275-goog Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Infact 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 commit 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@mail.gmail.com Fixes: f9e13c0a5a33 ("slab, slub: skip unnecessary kasan_cache_shutdown()") Signed-off-by: Shakeel Butt Suggested-by: David Rientjes Reported-by: Jason A . Donenfeld Cc: Christoph Lameter Cc: Pekka Enberg Cc: Joonsoo Kim Cc: Andrew Morton Cc: Andrey Ryabinin Cc: Cc: Cc: --- mm/slab.h | 2 +- mm/slub.c | 80 +++++++++++++++++++++++++------------------------------ 2 files changed, 38 insertions(+), 44 deletions(-) diff --git a/mm/slab.h b/mm/slab.h index 68bdf498da3b..a6545332cc86 100644 --- a/mm/slab.h +++ b/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 --git a/mm/slub.c b/mm/slub.c index a3b8467c14af..c9c190d54687 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1030,42 +1030,6 @@ static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct 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 int object_size, #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 -- 2.18.0.rc1.244.gcf134e6275-goog