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authorSean Rees <sean@erifax.org>2017-02-08 14:30:59 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-08 15:41:43 -0800
commita810007afe239d59c1115fcaa06eb5b480f876e9 (patch)
tree25bbc5efa479af7cb1ca2defeeffb2040600a2fd
parent4d59b6ccf000862beed6fc0765d3209f98a8d8a2 (diff)
mm/slub.c: fix random_seq offset destruction
Commit 210e7a43fa90 ("mm: SLUB freelist randomization") broke USB hub initialisation as described in https://bugzilla.kernel.org/show_bug.cgi?id=177551. Bail out early from init_cache_random_seq if s->random_seq is already initialised. This prevents destroying the previously computed random_seq offsets later in the function. If the offsets are destroyed, then shuffle_freelist will truncate page->freelist to just the first object (orphaning the rest). Fixes: 210e7a43fa90 ("mm: SLUB freelist randomization") Link: http://lkml.kernel.org/r/20170207140707.20824-1-sean@erifax.org Signed-off-by: Sean Rees <sean@erifax.org> Reported-by: <userwithuid@gmail.com> 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: Thomas Garnier <thgarnie@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/slub.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 7aa6f433f4de..7ec0a965c6a3 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1422,6 +1422,10 @@ static int init_cache_random_seq(struct kmem_cache *s)
int err;
unsigned long i, count = oo_objects(s->oo);
+ /* Bailout if already initialised */
+ if (s->random_seq)
+ return 0;
+
err = cache_random_seq_create(s, count, GFP_KERNEL);
if (err) {
pr_err("SLUB: Unable to initialize free list for %s\n",