From f3a3c320d54eea39a419fd539f5b0e9c74517b0a Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Tue, 15 Mar 2016 14:54:38 -0700 Subject: [PATCH] mm/slab: do not change cache size if debug pagealloc isn't possible We can fail to setup off slab in some conditions. Even in this case, debug pagealloc increases cache size to PAGE_SIZE in advance and it is waste because debug pagealloc cannot work for it when it isn't the off slab. To improve this situation, this patch checks first that this cache with increased size is suitable for off slab. It actually increases cache size when it is suitable for off-slab, so possible waste is removed. Signed-off-by: Joonsoo Kim Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Jesper Dangaard Brouer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slab.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index 9b56685fb79b..21aad9d518a7 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2206,10 +2206,17 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags) */ if (debug_pagealloc_enabled() && (flags & SLAB_POISON) && !slab_early_init && size >= kmalloc_size(INDEX_NODE) && - size >= 256 && cachep->object_size > cache_line_size() && - size < PAGE_SIZE) { - cachep->obj_offset += PAGE_SIZE - size; - size = PAGE_SIZE; + size >= 256 && cachep->object_size > cache_line_size()) { + if (size < PAGE_SIZE || size % PAGE_SIZE == 0) { + size_t tmp_size = ALIGN(size, PAGE_SIZE); + + if (set_off_slab_cache(cachep, tmp_size, flags)) { + flags |= CFLGS_OFF_SLAB; + cachep->obj_offset += tmp_size - size; + size = tmp_size; + goto done; + } + } } #endif -- 2.20.1