diff options
| author | Jens Axboe <axboe@kernel.dk> | 2012-11-06 12:24:26 +0100 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-12-06 11:20:34 +0000 |
| commit | de268a9f92b3b2504e9f87db3b4dd609aafb255f (patch) | |
| tree | e555b2b88a643616aedac9e1a63ab8be600eb89d | |
| parent | 66a572596853a2180272ca6a017cc32e8a56527c (diff) | |
dm: fix deadlock with request based dm and queue request_fn recursion
commit a8c32a5c98943d370ea606a2e7dc04717eb92206 upstream.
Request based dm attempts to re-run the request queue off the
request completion path. If used with a driver that potentially does
end_io from its request_fn, we could deadlock trying to recurse
back into request dispatch. Fix this by punting the request queue
run to kblockd.
Tested to fix a quickly reproducible deadlock in such a scenario.
Acked-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | drivers/md/dm.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 502dcf7565f4..895363049bef 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -755,8 +755,14 @@ static void rq_completed(struct mapped_device *md, int rw, int run_queue) if (!md_in_flight(md)) wake_up(&md->wait); + /* + * Run this off this callpath, as drivers could invoke end_io while + * inside their request_fn (and holding the queue lock). Calling + * back into ->request_fn() could deadlock attempting to grab the + * queue lock again. + */ if (run_queue) - blk_run_queue(md->queue); + blk_run_queue_async(md->queue); /* * dm_put() must be at the end of this function. See the comment above |