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slab: __GFP_ZERO is incompatible with a constructor

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__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: d07dbea464 ("Slab allocators: support __GFP_ZERO in all allocators")
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox 2018-06-07 17:05:13 -07:00 committed by Linus Torvalds
parent e56ee574bc
commit 128227e7fe
3 changed files with 7 additions and 1 deletions
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2
mm/slab.c
View File

@ -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) {

4
mm/slob.c
View File

@ -555,8 +555,10 @@ static void *slob_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
flags, node);
}
if (b && c->ctor)
if (b && c->ctor) {
WARN_ON_ONCE(flags & __GFP_ZERO);
c->ctor(b);
}
kmemleak_alloc_recursive(b, c->size, 1, c->flags, flags);
return b;

2
mm/slub.c
View File

@ -2444,6 +2444,8 @@ static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags,
struct kmem_cache_cpu *c = *pc;
struct page *page;
WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO));
freelist = get_partial(s, flags, node, c);
if (freelist)