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authorChristoph Lameter <clameter@sgi.com>2007-09-11 15:24:11 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-09-11 17:21:27 -0700
commitba0268a8b056f2ad846f1f8837a764c21bb6425e (patch)
tree93ab7d2555a98628850dbf917a43ceddef8c980c
parent4150d3f549fe2355625017b2a6ff72aec98bcef0 (diff)
downloadlinux-2.6.34-ux500-ba0268a8b056f2ad846f1f8837a764c21bb6425e.tar.gz
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 <clameter@sgi.com> Cc: Chuck Ebbert <cebbert@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/slub.c38
1 files changed, 23 insertions, 15 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 7defe84e6bd..addb20a6d67 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++;
/*