From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 24 Aug 2007 11:50:01 -0700 (PDT) From: Christoph Lameter Subject: SLUB: Accurately compare debug flags during slab cache merge In-Reply-To: <200708241804.l7OI4u4T007741@imap1.linux-foundation.org> Message-ID: References: <200708241804.l7OI4u4T007741@imap1.linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: davem@davemloft.net Cc: akpm@linux-foundation.org, linux-mm@kvack.org List-ID: SLUB: Accurately compare debug flags during slab cache merge Currently we simply add the debug flags unconditional when checking for a matching slab cache. This can create 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 debug flags if kmem_cache_open() would also add them. Create a function kmem_cache_flags() to calculate the flags to set on a slab cache and use kmem_cache_flags() to determine the flags in find_mergeable_slab(). Signed-off-by: Christoph Lameter --- mm/slub.c | 37 ++++++++++++++++++++++--------------- 1 file changed, 22 insertions(+), 15 deletions(-) Index: linux-2.6/mm/slub.c =================================================================== --- linux-2.6.orig/mm/slub.c 2007-08-24 11:14:02.000000000 -0700 +++ linux-2.6/mm/slub.c 2007-08-24 11:38:43.000000000 -0700 @@ -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 +1002,20 @@ static void kmem_cache_open_debug_check( * 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 +1032,12 @@ static inline int slab_pad_check(struct 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 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 /* @@ -2081,9 +2089,8 @@ static int kmem_cache_open(struct kmem_c 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; @@ -2653,7 +2660,7 @@ static int slab_unmergeable(struct kmem_ } 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; @@ -2667,6 +2674,7 @@ static struct kmem_cache *find_mergeable 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)) @@ -2675,8 +2683,7 @@ static struct kmem_cache *find_mergeable 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. @@ -2700,7 +2707,7 @@ struct kmem_cache *kmem_cache_create(con 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++; /* -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org