From ba0268a8b056f2ad846f1f8837a764c21bb6425e Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Tue, 11 Sep 2007 15:24:11 -0700 Subject: [PATCH] SLUB: accurately compare debug flags during slab cache merge This was posted on Aug 28 and fixes an issue that could cause troubles when slab caches >=128k are created. http://marc.info/?l=linux-mm&m=118798149918424&w=2 Currently we simply add the debug flags unconditional when checking for a matching slab. This creates issues for sysfs processing when slabs exist that are exempt from debugging due to their huge size or because only a subset of slabs was selected for debugging. We need to only add the flags if kmem_cache_open() would also add them. Create a function to calculate the flags that would be set if the cache would be opened and use that function to determine the flags before looking for a compatible slab. [akpm@linux-foundation.org: fixlets] Signed-off-by: Christoph Lameter Cc: Chuck Ebbert Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slub.c | 38 +++++++++++++++++++++++--------------- 1 file changed, 23 insertions(+), 15 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 7defe84e6bd0..addb20a6d67d 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -986,7 +986,9 @@ out: __setup("slub_debug", setup_slub_debug); -static void kmem_cache_open_debug_check(struct kmem_cache *s) +static unsigned long kmem_cache_flags(unsigned long objsize, + unsigned long flags, const char *name, + void (*ctor)(void *, struct kmem_cache *, unsigned long)) { /* * The page->offset field is only 16 bit wide. This is an offset @@ -1000,19 +1002,21 @@ static void kmem_cache_open_debug_check(struct kmem_cache *s) * Debugging or ctor may create a need to move the free * pointer. Fail if this happens. */ - if (s->objsize >= 65535 * sizeof(void *)) { - BUG_ON(s->flags & (SLAB_RED_ZONE | SLAB_POISON | + if (objsize >= 65535 * sizeof(void *)) { + BUG_ON(flags & (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | SLAB_DESTROY_BY_RCU)); - BUG_ON(s->ctor); - } - else + BUG_ON(ctor); + } else { /* * Enable debugging if selected on the kernel commandline. */ if (slub_debug && (!slub_debug_slabs || - strncmp(slub_debug_slabs, s->name, + strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs)) == 0)) - s->flags |= slub_debug; + flags |= slub_debug; + } + + return flags; } #else static inline void setup_object_debug(struct kmem_cache *s, @@ -1029,7 +1033,12 @@ static inline int slab_pad_check(struct kmem_cache *s, struct page *page) static inline int check_object(struct kmem_cache *s, struct page *page, void *object, int active) { return 1; } static inline void add_full(struct kmem_cache_node *n, struct page *page) {} -static inline void kmem_cache_open_debug_check(struct kmem_cache *s) {} +static inline unsigned long kmem_cache_flags(unsigned long objsize, + unsigned long flags, const char *name, + void (*ctor)(void *, struct kmem_cache *, unsigned long)) +{ + return flags; +} #define slub_debug 0 #endif /* @@ -2088,9 +2097,8 @@ static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags, s->name = name; s->ctor = ctor; s->objsize = size; - s->flags = flags; s->align = align; - kmem_cache_open_debug_check(s); + s->flags = kmem_cache_flags(size, flags, name, ctor); if (!calculate_sizes(s)) goto error; @@ -2660,7 +2668,7 @@ static int slab_unmergeable(struct kmem_cache *s) } static struct kmem_cache *find_mergeable(size_t size, - size_t align, unsigned long flags, + size_t align, unsigned long flags, const char *name, void (*ctor)(void *, struct kmem_cache *, unsigned long)) { struct kmem_cache *s; @@ -2674,6 +2682,7 @@ static struct kmem_cache *find_mergeable(size_t size, size = ALIGN(size, sizeof(void *)); align = calculate_alignment(flags, align, size); size = ALIGN(size, align); + flags = kmem_cache_flags(size, flags, name, NULL); list_for_each_entry(s, &slab_caches, list) { if (slab_unmergeable(s)) @@ -2682,8 +2691,7 @@ static struct kmem_cache *find_mergeable(size_t size, if (size > s->size) continue; - if (((flags | slub_debug) & SLUB_MERGE_SAME) != - (s->flags & SLUB_MERGE_SAME)) + if ((flags & SLUB_MERGE_SAME) != (s->flags & SLUB_MERGE_SAME)) continue; /* * Check if alignment is compatible. @@ -2707,7 +2715,7 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, struct kmem_cache *s; down_write(&slub_lock); - s = find_mergeable(size, align, flags, ctor); + s = find_mergeable(size, align, flags, name, ctor); if (s) { s->refcount++; /* -- 2.30.2