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| author | Ingo Molnar <mingo@elte.hu> | 2006-06-23 11:03:46 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-23 16:42:52 +0200 |
| commit | e0a42726794f71336ff4b26084d453dd597471ce (patch) | |
| tree | 31debb23f7cce0510a63755f0c4297086761f623 | |
| parent | [PATCH] fix update_mmu_cache in fremap.c (diff) | |
| download | linux-e0a42726794f71336ff4b26084d453dd597471ce.tar.xz linux-e0a42726794f71336ff4b26084d453dd597471ce.zip | |
[PATCH] mm/slab.c: fix early init assumption
The SLAB bootstrap code assumes that the first two kmalloc caches created
(the INDEX_AC and INDEX_L3 kmalloc caches) wont be off-slab. But due to AC
and L3 structure size increase in lockdep, one of them ended up being
off-slab, and subsequently crashing with:
Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP:
[<ffffffff80267478>] kmem_cache_alloc+0x26/0x7d
The fix is to introduce a bootstrap flag and to use it to prevent off-slab
caches being created so early during bootup.
(The calculation for off-slab caches is quite complex so i didnt want to
complicate things with introducing yet another INDEX_ calculation, the flag
approach is simpler and smaller.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | mm/slab.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/mm/slab.c b/mm/slab.c index e3260db04b9e..664c3a10acf2 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -331,6 +331,8 @@ static __always_inline int index_of(const size_t size) return 0; } +static int slab_early_init = 1; + #define INDEX_AC index_of(sizeof(struct arraycache_init)) #define INDEX_L3 index_of(sizeof(struct kmem_list3)) @@ -1376,6 +1378,8 @@ void __init kmem_cache_init(void) NULL, NULL); } + slab_early_init = 0; + while (sizes->cs_size != ULONG_MAX) { /* * For performance, all the general caches are L1 aligned. @@ -2106,8 +2110,12 @@ kmem_cache_create (const char *name, size_t size, size_t align, #endif #endif - /* Determine if the slab management is 'on' or 'off' slab. */ - if (size >= (PAGE_SIZE >> 3)) + /* + * Determine if the slab management is 'on' or 'off' slab. + * (bootstrapping cannot cope with offslab caches so don't do + * it too early on.) + */ + if ((size >= (PAGE_SIZE >> 3)) && !slab_early_init) /* * Size is large, assume best to place the slab management obj * off-slab (should allow better packing of objs). |