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authorMatthew Wilcox <mawilcox@microsoft.com>2018-06-07 17:05:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-06-07 17:34:34 -0700
commit128227e7fe4087b60f1bd31f762e61237eb23790 (patch)
treeccf03475b150751d98f4f901339a3871dafe8240
parente56ee574bc46b9734066008b3dc105bd7d4cbc0c (diff)
downloadlinux-128227e7fe4087b60f1bd31f762e61237eb23790.tar.bz2
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 <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>
-rw-r--r--mm/slab.c2
-rw-r--r--mm/slob.c4
-rw-r--r--mm/slub.c2
3 files changed, 7 insertions, 1 deletions
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) {
diff --git a/mm/slob.c b/mm/slob.c
index 623e8a5c46ce..307c2c9feb44 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -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;
diff --git a/mm/slub.c b/mm/slub.c
index 44aa7847324a..dc960401ce90 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -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)