From 683d0baad3d6e18134927f8c28ee804dbe10fe71 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Mon, 7 Jan 2008 23:20:29 -0800 Subject: SLUB: Use unique end pointer for each slab page. We use a NULL pointer on freelists to signal that there are no more objects. However the NULL pointers of all slabs match in contrast to the pointers to the real objects which are in different ranges for different slab pages. Change the end pointer to be a pointer to the first object and set bit 0. Every slab will then have a different end pointer. This is necessary to ensure that end markers can be matched to the source slab during cmpxchg_local. Bring back the use of the mapping field by SLUB since we would otherwise have to call a relatively expensive function page_address() in __slab_alloc(). Use of the mapping field allows avoiding a call to page_address() in various other functions as well. There is no need to change the page_mapping() function since bit 0 is set on the mapping as also for anonymous pages. page_mapping(slab_page) will therefore still return NULL although the mapping field is overloaded. Signed-off-by: Christoph Lameter Cc: Pekka Enberg Signed-off-by: Andrew Morton --- include/linux/mm_types.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 34023c65d46..bfee0bd1d43 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -64,7 +64,10 @@ struct page { #if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS spinlock_t ptl; #endif - struct kmem_cache *slab; /* SLUB: Pointer to slab */ + struct { + struct kmem_cache *slab; /* SLUB: Pointer to slab */ + void *end; /* SLUB: end marker */ + }; struct page *first_page; /* Compound tail pages */ }; union { -- cgit v1.2.3