4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sean Rees <s...@erifax.org>
commit a810007afe239d59c1115fcaa06eb5b480f876e9 upstream.
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-s...@erifax.org
Signed-off-by: Sean Rees <s...@erifax.org>
Reported-by: <userwith...@gmail.com>
Cc: Christoph Lameter <c...@linux.com>
Cc: Pekka Enberg <penb...@kernel.org>
Cc: David Rientjes <rient...@google.com>
Cc: Joonsoo Kim <iamjoonsoo....@lge.com>
Cc: Thomas Garnier <thgar...@google.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
mm/slub.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1419,6 +1419,10 @@ static int init_cache_random_seq(struct
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",
