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| author | Jens Axboe <axboe@kernel.dk> | 2012-11-06 12:24:26 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-12-03 12:59:14 -0800 |
| commit | 2d7c6b713f9479a02e4a8e7159dc32ad160c8da7 (patch) | |
| tree | cf99261a0135d3f7e8b541e9fbc30cf2da8518d1 /drivers/md | |
| parent | 38f6449bb781860f9a6b62102e5aea75fe4e7945 (diff) | |
| download | kernel_samsung_smdk4412-2d7c6b713f9479a02e4a8e7159dc32ad160c8da7.zip kernel_samsung_smdk4412-2d7c6b713f9479a02e4a8e7159dc32ad160c8da7.tar.gz kernel_samsung_smdk4412-2d7c6b713f9479a02e4a8e7159dc32ad160c8da7.tar.bz2 | |
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/md')
| -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 1889b1e..9f472d5 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -745,8 +745,14 @@ 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 |