The patch titled
Subject: slab: __GFP_ZERO is incompatible with a constructor
has been added to the -mm tree. Its filename is
slab-__gfp_zero-is-incompatible-with-a-constructor.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/slab-__gfp_zero-is-incompatible-with-a-constructor.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/slab-__gfp_zero-is-incompatible-with-a-constructor.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxxxx
Fixes: d07dbea46405 ("Slab allocators: support __GFP_ZERO in all allocators")
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slab.c | 2 ++
mm/slob.c | 4 +++-
mm/slub.c | 2 ++
3 files changed, 7 insertions(+), 1 deletion(-)
diff -puN mm/slab.c~slab-__gfp_zero-is-incompatible-with-a-constructor mm/slab.c
--- a/mm/slab.c~slab-__gfp_zero-is-incompatible-with-a-constructor
+++ a/mm/slab.c
@@ -2665,6 +2665,7 @@ static struct page *cache_grow_begin(str
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_debugchec
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 -puN mm/slob.c~slab-__gfp_zero-is-incompatible-with-a-constructor mm/slob.c
--- a/mm/slob.c~slab-__gfp_zero-is-incompatible-with-a-constructor
+++ a/mm/slob.c
@@ -555,8 +555,10 @@ static void *slob_alloc_node(struct kmem
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 -puN mm/slub.c~slab-__gfp_zero-is-incompatible-with-a-constructor mm/slub.c
--- a/mm/slub.c~slab-__gfp_zero-is-incompatible-with-a-constructor
+++ a/mm/slub.c
@@ -2444,6 +2444,8 @@ static inline void *new_slab_objects(str
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)
_
Patches currently in -mm which might be from mawilcox@xxxxxxxxxxxxx are
fix-null-pointer-in-page_cache_tree_insert.patch
slab-__gfp_zero-is-incompatible-with-a-constructor.patch
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