diff options
| author | Jens Axboe <axboe@fb.com> | 2014-10-07 08:39:20 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-11-14 10:10:25 -0800 |
| commit | 7d515b57a1457c9dc4113bc471e686f2b7e79474 (patch) | |
| tree | 2ceb8e6afe01c62dd053962697afec743e130216 /block | |
| parent | 8c7130220e2f3c64f9ef67aa576064df496cae84 (diff) | |
blk-mq: fix potential hang if rolling wakeup depth is too high
commit abab13b5c4fd1fec4f9a61622548012d93dc2831 upstream.
We currently divide the queue depth by 4 as our batch wakeup
count, but we split the wakeups over BT_WAIT_QUEUES number of
wait queues. This defaults to 8. If the product of the resulting
batch wake count and BT_WAIT_QUEUES is higher than the device
queue depth, we can get into a situation where a task goes to
sleep waiting for a request, but never gets woken up.
Reported-by: Bart Van Assche <bvanassche@acm.org>
Fixes: 4bb659b156996
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-mq-tag.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index c1b92426c95e..74a4168ea34e 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -463,8 +463,8 @@ static void bt_update_count(struct blk_mq_bitmap_tags *bt, } bt->wake_cnt = BT_WAIT_BATCH; - if (bt->wake_cnt > depth / 4) - bt->wake_cnt = max(1U, depth / 4); + if (bt->wake_cnt > depth / BT_WAIT_QUEUES) + bt->wake_cnt = max(1U, depth / BT_WAIT_QUEUES); bt->depth = depth; } |