From 128227e7fe4087b60f1bd31f762e61237eb23790 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Thu, 7 Jun 2018 17:05:13 -0700 Subject: slab: __GFP_ZERO is incompatible with a constructor __GFP_ZERO requests that the object be initialised to all-zeroes, while the purpose of a constructor is to initialise an object to a particular pattern. We cannot do both. Add a warning to catch any users who mistakenly pass a __GFP_ZERO flag when allocating a slab with a constructor. Link: http://lkml.kernel.org/r/20180412191322.GA21205@bombadil.infradead.org Fixes: d07dbea46405 ("Slab allocators: support __GFP_ZERO in all allocators") Signed-off-by: Matthew Wilcox Acked-by: Johannes Weiner Acked-by: Vlastimil Babka Acked-by: Michal Hocko Reviewed-by: Andrew Morton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slab.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'mm/slab.c') diff --git a/mm/slab.c b/mm/slab.c index 2f308253c3d7..c1fe8099b3cd 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2665,6 +2665,7 @@ static struct page *cache_grow_begin(struct kmem_cache *cachep, invalid_mask, &invalid_mask, flags, &flags); dump_stack(); } + WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO)); local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK); check_irq_off(); @@ -3071,6 +3072,7 @@ static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep, static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep, gfp_t flags, void *objp, unsigned long caller) { + WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO)); if (!objp) return objp; if (cachep->flags & SLAB_POISON) { -- cgit