From: Grygorii Maistrenko <grygoriimkd@xxxxxxxxx> [ Upstream commit c6e28895a4372992961888ffaadc9efc643b5bfe ] In case CONFIG_SLUB_DEBUG_ON=n, find_mergeable() gets debug features from commandline but never checks if there are features from the SLAB_NEVER_MERGE set. As a result selected by slub_debug caches are always mergeable if they have been created without a custom constructor set or without one of the SLAB_* debug features on. This moves the SLAB_NEVER_MERGE check below the flags update from commandline to make sure it won't merge the slab cache if one of the debug features is on. Link: http://lkml.kernel.org/r/20170101124451.GA4740@lp-laptop-d Signed-off-by: Grygorii Maistrenko <grygoriimkd@xxxxxxxxx> Reviewed-by: Pekka Enberg <penberg@xxxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Acked-by: Christoph Lameter <cl@xxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> --- mm/slab_common.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index bec2fce9fafc..01e7246de8df 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -250,7 +250,7 @@ struct kmem_cache *find_mergeable(size_t size, size_t align, { struct kmem_cache *s; - if (slab_nomerge || (flags & SLAB_NEVER_MERGE)) + if (slab_nomerge) return NULL; if (ctor) @@ -261,6 +261,9 @@ struct kmem_cache *find_mergeable(size_t size, size_t align, size = ALIGN(size, align); flags = kmem_cache_flags(size, flags, name, NULL); + if (flags & SLAB_NEVER_MERGE) + return NULL; + list_for_each_entry_reverse(s, &slab_caches, list) { if (slab_unmergeable(s)) continue; -- 2.11.0