diff options
author | Zachary Hays <zhays@lexmark.com> | 2019-02-07 10:03:08 -0500 |
---|---|---|
committer | Ulf Hansson <ulf.hansson@linaro.org> | 2019-02-08 12:24:17 +0100 |
commit | dcf6e2e38a1c7ccbc535de5e1d9b14998847499d (patch) | |
tree | 6b54c5ee87b59511e819c1582a4d3f79aeb70025 /include | |
parent | d6f11e7d91f2ac85f66194fe3ef8789b49901d64 (diff) |
mmc: block: handle complete_work on separate workqueue
The kblockd workqueue is created with the WQ_MEM_RECLAIM flag set.
This generates a rescuer thread for that queue that will trigger when
the CPU is under heavy load and collect the uncompleted work.
In the case of mmc, this creates the possibility of a deadlock when
there are multiple partitions on the device as other blk-mq work is
also run on the same queue. For example:
- worker 0 claims the mmc host to work on partition 1
- worker 1 attempts to claim the host for partition 2 but has to wait
for worker 0 to finish
- worker 0 schedules complete_work to release the host
- rescuer thread is triggered after time-out and collects the dangling
work
- rescuer thread attempts to complete the work in order starting with
claim host
- the task to release host is now blocked by a task to claim it and
will never be called
The above results in multiple hung tasks that lead to failures to
mount partitions.
Handling complete_work on a separate workqueue avoids this by keeping
the work completion tasks separate from the other blk-mq work. This
allows the host to be released without getting blocked by other tasks
attempting to claim the host.
Signed-off-by: Zachary Hays <zhays@lexmark.com>
Fixes: 81196976ed94 ("mmc: block: Add blk-mq support")
Cc: <stable@vger.kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/mmc/card.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h index de7377815b6b..8ef330027b13 100644 --- a/include/linux/mmc/card.h +++ b/include/linux/mmc/card.h @@ -308,6 +308,7 @@ struct mmc_card { unsigned int nr_parts; unsigned int bouncesz; /* Bounce buffer size */ + struct workqueue_struct *complete_wq; /* Private workqueue */ }; static inline bool mmc_large_sector(struct mmc_card *card) |