dm: fix deadlock with request based dm and queue request_fn recursion
authorJens Axboe <axboe@kernel.dk>
Tue, 6 Nov 2012 11:24:26 +0000 (12:24 +0100)
committerBen Hutchings <ben@decadent.org.uk>
Thu, 6 Dec 2012 11:20:34 +0000 (11:20 +0000)
commitde268a9f92b3b2504e9f87db3b4dd609aafb255f
treee555b2b88a643616aedac9e1a63ab8be600eb89d
parent66a572596853a2180272ca6a017cc32e8a56527c
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>
drivers/md/dm.c