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authorIngo Molnar <mingo@elte.hu>2006-06-23 02:03:46 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-23 07:42:52 -0700
commite0a42726794f71336ff4b26084d453dd597471ce (patch)
tree31debb23f7cce0510a63755f0c4297086761f623 /mm/slab.c
parent668e0d8f1a02fd75f1c1e8142a6b08455914242c (diff)
downloadop-kernel-dev-e0a42726794f71336ff4b26084d453dd597471ce.zip
op-kernel-dev-e0a42726794f71336ff4b26084d453dd597471ce.tar.gz
[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>
Diffstat (limited to 'mm/slab.c')
-rw-r--r--mm/slab.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/mm/slab.c b/mm/slab.c
index e3260db..664c3a10 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).
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