diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2020-02-17 15:43:03 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-03-11 16:15:13 +0300 |
| commit | bd68d2206bb832aed06d4feac79097c0cc3228e9 (patch) | |
| tree | 189b9fbda16ecfbccf5ade04c62826725b6c7b52 /drivers/md | |
| parent | 9e6eb1876cfc2c9437162899b40ecd2561d4e293 (diff) | |
| download | linux-bd68d2206bb832aed06d4feac79097c0cc3228e9.tar.xz | |
dm integrity: fix a deadlock due to offloading to an incorrect workqueue
commit 53770f0ec5fd417429775ba006bc4abe14002335 upstream.
If we need to perform synchronous I/O in dm_integrity_map_continue(),
we must make sure that we are not in the map function - in order to
avoid the deadlock due to bio queuing in generic_make_request. To
avoid the deadlock, we offload the request to metadata_wq.
However, metadata_wq also processes metadata updates for write requests.
If there are too many requests that get offloaded to metadata_wq at the
beginning of dm_integrity_map_continue, the workqueue metadata_wq
becomes clogged and the system is incapable of processing any metadata
updates.
This causes a deadlock because all the requests that need to do metadata
updates wait for metadata_wq to proceed and metadata_wq waits inside
wait_and_add_new_range until some existing request releases its range
lock (which doesn't happen because the range lock is released after
metadata update).
In order to fix the deadlock, we create a new workqueue offload_wq and
offload requests to it - so that processing of offload_wq is independent
from processing of metadata_wq.
Fixes: 7eada909bfd7 ("dm: add integrity target")
Cc: stable@vger.kernel.org # v4.12+
Reported-by: Heinz Mauelshagen <heinzm@redhat.com>
Tested-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-integrity.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c index a493bebefd69..5885239cc1f8 100644 --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -198,6 +198,7 @@ struct dm_integrity_c { struct list_head wait_list; wait_queue_head_t endio_wait; struct workqueue_struct *wait_wq; + struct workqueue_struct *offload_wq; unsigned char commit_seq; commit_id_t commit_ids[N_COMMIT_IDS]; @@ -1237,7 +1238,7 @@ static void dec_in_flight(struct dm_integrity_io *dio) dio->range.logical_sector += dio->range.n_sectors; bio_advance(bio, dio->range.n_sectors << SECTOR_SHIFT); INIT_WORK(&dio->work, integrity_bio_wait); - queue_work(ic->wait_wq, &dio->work); + queue_work(ic->offload_wq, &dio->work); return; } do_endio_flush(ic, dio); @@ -1657,7 +1658,7 @@ static void dm_integrity_map_continue(struct dm_integrity_io *dio, bool from_map if (need_sync_io && from_map) { INIT_WORK(&dio->work, integrity_bio_wait); - queue_work(ic->metadata_wq, &dio->work); + queue_work(ic->offload_wq, &dio->work); return; } @@ -3308,6 +3309,14 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv) goto bad; } + ic->offload_wq = alloc_workqueue("dm-integrity-offload", WQ_MEM_RECLAIM, + METADATA_WORKQUEUE_MAX_ACTIVE); + if (!ic->offload_wq) { + ti->error = "Cannot allocate workqueue"; + r = -ENOMEM; + goto bad; + } + ic->commit_wq = alloc_workqueue("dm-integrity-commit", WQ_MEM_RECLAIM, 1); if (!ic->commit_wq) { ti->error = "Cannot allocate workqueue"; @@ -3544,6 +3553,8 @@ static void dm_integrity_dtr(struct dm_target *ti) destroy_workqueue(ic->metadata_wq); if (ic->wait_wq) destroy_workqueue(ic->wait_wq); + if (ic->offload_wq) + destroy_workqueue(ic->offload_wq); if (ic->commit_wq) destroy_workqueue(ic->commit_wq); if (ic->writer_wq) |