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authorRon Lee <ron@debian.org>2009-05-22 04:58:22 +0930
committerPekka Enberg <penberg@cs.helsinki.fi>2009-05-22 11:01:12 +0300
commit6746136520cd0827320a83e62d0a023a5a433650 (patch)
tree2e57aef24fbb8e8531aad10061245ec4bddda6f9 /mm/slab.c
parent45d447406a19cbfd42720f066f156f4eb9d68801 (diff)
downloadlwn-6746136520cd0827320a83e62d0a023a5a433650.tar.gz
lwn-6746136520cd0827320a83e62d0a023a5a433650.zip
slab: fix generic PAGE_POISONING conflict with SLAB_RED_ZONE
A generic page poisoning mechanism was added with commit: 6a11f75b6a17b5d9ac5025f8d048382fd1f47377 which destructively poisons full pages with a bitpattern. On arches where PAGE_POISONING is used, this conflicts with the slab redzone checking enabled by DEBUG_SLAB, scribbling bits all over its magic words and making it complain about that quite emphatically. On x86 (and I presume at present all the other arches which set ARCH_SUPPORTS_DEBUG_PAGEALLOC too), the kernel_map_pages() operation is non destructive so it can coexist with the other DEBUG_SLAB mechanisms just fine. This patch favours the expensive full page destruction test for cases where there is a collision and it is explicitly selected. Signed-off-by: Ron Lee <ron@debian.org> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Diffstat (limited to 'mm/slab.c')
-rw-r--r--mm/slab.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/mm/slab.c b/mm/slab.c
index 9a90b00d2f91..1a6040d0f41d 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2353,6 +2353,15 @@ kmem_cache_create (const char *name, size_t size, size_t align,
/* really off slab. No need for manual alignment */
slab_size =
cachep->num * sizeof(kmem_bufctl_t) + sizeof(struct slab);
+
+#ifdef CONFIG_PAGE_POISONING
+ /* If we're going to use the generic kernel_map_pages()
+ * poisoning, then it's going to smash the contents of
+ * the redzone and userword anyhow, so switch them off.
+ */
+ if (size % PAGE_SIZE == 0 && flags & SLAB_POISON)
+ flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
+#endif
}
cachep->colour_off = cache_line_size();