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| author | Arnd Bergmann <arnd@arndb.de> | 2016-12-13 01:41:35 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-13 03:55:06 +0100 |
| commit | 84582c8ab9479ffa4532afa95ab8d8f96b5478dc (patch) | |
| tree | 3dfcb024b303d52f04b64503ab86ff7ca46917fb | |
| parent | slub: move synchronize_sched out of slab_mutex on shrink (diff) | |
| download | linux-84582c8ab9479ffa4532afa95ab8d8f96b5478dc.tar.xz linux-84582c8ab9479ffa4532afa95ab8d8f96b5478dc.zip | |
slub: avoid false-postive warning
The slub allocator gives us some incorrect warnings when
CONFIG_PROFILE_ANNOTATED_BRANCHES is set, as the unlikely() macro
prevents it from seeing that the return code matches what it was before:
mm/slub.c: In function `kmem_cache_free_bulk':
mm/slub.c:262:23: error: `df.s' may be used uninitialized in this function [-Werror=maybe-uninitialized]
mm/slub.c:2943:3: error: `df.cnt' may be used uninitialized in this function [-Werror=maybe-uninitialized]
mm/slub.c:2933:4470: error: `df.freelist' may be used uninitialized in this function [-Werror=maybe-uninitialized]
mm/slub.c:2943:3: error: `df.tail' may be used uninitialized in this function [-Werror=maybe-uninitialized]
I have not been able to come up with a perfect way for dealing with
this, the three options I see are:
- add a bogus initialization, which would increase the runtime overhead
- replace unlikely() with unlikely_notrace()
- remove the unlikely() annotation completely
I checked the object code for a typical x86 configuration and the last
two cases produce the same result, so I went for the last one, which is
the simplest.
Link: http://lkml.kernel.org/r/20161024155704.3114445-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Laura Abbott <labbott@fedoraproject.org>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/slub.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/slub.c b/mm/slub.c index 4a861f265cd7..067598a00849 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3076,7 +3076,7 @@ void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p) struct detached_freelist df; size = build_detached_freelist(s, size, p, &df); - if (unlikely(!df.page)) + if (!df.page) continue; slab_free(df.s, df.page, df.freelist, df.tail, df.cnt,_RET_IP_); |