From: Satyam Sharma Considering kfree(NULL) would normally occur only in error paths and kfree(ZERO_SIZE_PTR) is uncommon as well, so let's use unlikely() for the condition check in SLUB's and SLOB's kfree() to optimize for the common case. SLAB has this already. Signed-off-by: Satyam Sharma Cc: Pekka Enberg Cc: Christoph Lameter Signed-off-by: Andrew Morton --- mm/slob.c | 6 +++--- mm/slub.c | 8 ++++---- 2 files changed, 7 insertions(+), 7 deletions(-) diff -puN mm/slob.c~slub-slob-use-unlikely-for-kfreezero_or_null_ptr-check mm/slob.c --- a/mm/slob.c~slub-slob-use-unlikely-for-kfreezero_or_null_ptr-check +++ a/mm/slob.c @@ -360,7 +360,7 @@ static void slob_free(void *block, int s slobidx_t units; unsigned long flags; - if (ZERO_OR_NULL_PTR(block)) + if (unlikely(ZERO_OR_NULL_PTR(block))) return; BUG_ON(!size); @@ -466,7 +466,7 @@ void kfree(const void *block) { struct slob_page *sp; - if (ZERO_OR_NULL_PTR(block)) + if (unlikely(ZERO_OR_NULL_PTR(block))) return; sp = (struct slob_page *)virt_to_page(block); @@ -484,7 +484,7 @@ size_t ksize(const void *block) { struct slob_page *sp; - if (ZERO_OR_NULL_PTR(block)) + if (unlikely(ZERO_OR_NULL_PTR(block))) return 0; sp = (struct slob_page *)virt_to_page(block); diff -puN mm/slub.c~slub-slob-use-unlikely-for-kfreezero_or_null_ptr-check mm/slub.c --- a/mm/slub.c~slub-slob-use-unlikely-for-kfreezero_or_null_ptr-check +++ a/mm/slub.c @@ -2441,7 +2441,7 @@ size_t ksize(const void *object) struct page *page; struct kmem_cache *s; - if (ZERO_OR_NULL_PTR(object)) + if (unlikely(ZERO_OR_NULL_PTR(object))) return 0; page = get_object_page(object); @@ -2475,7 +2475,7 @@ void kfree(const void *x) { struct page *page; - if (ZERO_OR_NULL_PTR(x)) + if (unlikely(ZERO_OR_NULL_PTR(x))) return; page = virt_to_head_page(x); @@ -2792,7 +2792,7 @@ void *__kmalloc_track_caller(size_t size get_order(size)); s = get_slab(size, gfpflags); - if (ZERO_OR_NULL_PTR(s)) + if (unlikely(ZERO_OR_NULL_PTR(s))) return s; return slab_alloc(s, gfpflags, -1, caller); @@ -2808,7 +2808,7 @@ void *__kmalloc_node_track_caller(size_t get_order(size)); s = get_slab(size, gfpflags); - if (ZERO_OR_NULL_PTR(s)) + if (unlikely(ZERO_OR_NULL_PTR(s))) return s; return slab_alloc(s, gfpflags, node, caller); _