From 614410d5892af5f86d0ec14e28f9f6d5f4ac9e9b Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Sun, 6 May 2007 14:49:38 -0700 Subject: [PATCH] SLUB: allocate smallest object size if the user asks for 0 bytes Makes SLUB behave like SLAB in this area to avoid issues.... Throw a stack dump to alert people. At some point the behavior should be switched back. NULL is no memory as far as I can tell and if the use asked for 0 bytes then he need to get no memory. Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/slub_def.h | 8 ++++++-- mm/slub.c | 2 +- 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index 30b154ce7289..f8e0c86c48a9 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -80,8 +80,12 @@ extern struct kmem_cache kmalloc_caches[KMALLOC_SHIFT_HIGH + 1]; */ static inline int kmalloc_index(int size) { - if (size == 0) - return 0; + /* + * We should return 0 if size == 0 but we use the smallest object + * here for SLAB legacy reasons. + */ + WARN_ON_ONCE(size == 0); + if (size > 64 && size <= 96) return 1; if (size > 128 && size <= 192) diff --git a/mm/slub.c b/mm/slub.c index 4a8585befd84..9d52cce7c999 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1979,7 +1979,7 @@ static struct kmem_cache *get_slab(size_t size, gfp_t flags) { int index = kmalloc_index(size); - if (!size) + if (!index) return NULL; /* Allocation too large? */ -- 2.20.1