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| author | Yu Kuai <yukuai3@huawei.com> | 2023-06-10 05:30:43 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-07-19 17:20:55 +0300 |
| commit | 931bd6758bcc0f3d27d0492456798afae028e52f (patch) | |
| tree | e8404c4dcabce4ada87dfba4b6905b0cf2ba92db /include | |
| parent | c2a0eb3b2017bd1ab8bc68f9296619036a3d06df (diff) | |
| download | linux-931bd6758bcc0f3d27d0492456798afae028e52f.tar.xz | |
blk-mq: fix potential io hang by wrong 'wake_batch'
[ Upstream commit 4f1731df60f9033669f024d06ae26a6301260b55 ]
In __blk_mq_tag_busy/idle(), updating 'active_queues' and calculating
'wake_batch' is not atomic:
t1: t2:
_blk_mq_tag_busy blk_mq_tag_busy
inc active_queues
// assume 1->2
inc active_queues
// 2 -> 3
blk_mq_update_wake_batch
// calculate based on 3
blk_mq_update_wake_batch
/* calculate based on 2, while active_queues is actually 3. */
Fix this problem by protecting them wih 'tags->lock', this is not a hot
path, so performance should not be concerned. And now that all writers
are inside the lock, switch 'actives_queues' from atomic to unsigned
int.
Fixes: 180dccb0dba4 ("blk-mq: fix tag_get wait task can't be awakened")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230610023043.2559121-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/blk-mq.h | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index a9764cbf7f8d..e4f676e1042b 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -745,8 +745,7 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, struct blk_mq_tags { unsigned int nr_tags; unsigned int nr_reserved_tags; - - atomic_t active_queues; + unsigned int active_queues; struct sbitmap_queue bitmap_tags; struct sbitmap_queue breserved_tags; |