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authorMikulas Patocka <mpatocka@redhat.com>2020-02-19 10:25:45 -0500
committerMike Snitzer <snitzer@redhat.com>2020-02-27 12:00:52 -0500
commit7cdf6a0aae1cccf5167f3f04ecddcf648b78e289 (patch)
tree115172a66547e3074c3c57ada5dd5ac130a98f4d /drivers
parent7fc2e47f40dd77ab1fcbda6db89614a0173d89c7 (diff)
dm cache: fix a crash due to incorrect work item cancelling
The crash can be reproduced by running the lvm2 testsuite test lvconvert-thin-external-cache.sh for several minutes, e.g.: while :; do make check T=shell/lvconvert-thin-external-cache.sh; done The crash happens in this call chain: do_waker -> policy_tick -> smq_tick -> end_hotspot_period -> clear_bitset -> memset -> __memset -- which accesses an invalid pointer in the vmalloc area. The work entry on the workqueue is executed even after the bitmap was freed. The problem is that cancel_delayed_work doesn't wait for the running work item to finish, so the work item can continue running and re-submitting itself even after cache_postsuspend. In order to make sure that the work item won't be running, we must use cancel_delayed_work_sync. Also, change flush_workqueue to drain_workqueue, so that if some work item submits itself or another work item, we are properly waiting for both of them. Fixes: c6b4fcbad044 ("dm: add cache target") Cc: stable@vger.kernel.org # v3.9 Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/md/dm-cache-target.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 2d32821b3a5b..f4be63671233 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -2846,8 +2846,8 @@ static void cache_postsuspend(struct dm_target *ti)
prevent_background_work(cache);
BUG_ON(atomic_read(&cache->nr_io_migrations));
- cancel_delayed_work(&cache->waker);
- flush_workqueue(cache->wq);
+ cancel_delayed_work_sync(&cache->waker);
+ drain_workqueue(cache->wq);
WARN_ON(cache->tracker.in_flight);
/*