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| author | Yu Kuai <yukuai3@huawei.com> | 2023-06-10 10:30:43 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-06-12 09:55:53 -0600 |
| commit | 4f1731df60f9033669f024d06ae26a6301260b55 (patch) | |
| tree | 8b3d6dbff9e497e9b2ecf9603284499be48a2bde /block/blk-mq-debugfs.c | |
| parent | 0733ad8002916b9dbbbcfe6e92ad44d2657de1c1 (diff) | |
| download | linux-stable-4f1731df60f9033669f024d06ae26a6301260b55.tar.gz linux-stable-4f1731df60f9033669f024d06ae26a6301260b55.tar.bz2 linux-stable-4f1731df60f9033669f024d06ae26a6301260b55.zip | |
blk-mq: fix potential io hang by wrong 'wake_batch'
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>
Diffstat (limited to 'block/blk-mq-debugfs.c')
| -rw-r--r-- | block/blk-mq-debugfs.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c index 68165a50951b..c3b5930106b2 100644 --- a/block/blk-mq-debugfs.c +++ b/block/blk-mq-debugfs.c @@ -401,7 +401,7 @@ static void blk_mq_debugfs_tags_show(struct seq_file *m, seq_printf(m, "nr_tags=%u\n", tags->nr_tags); seq_printf(m, "nr_reserved_tags=%u\n", tags->nr_reserved_tags); seq_printf(m, "active_queues=%d\n", - atomic_read(&tags->active_queues)); + READ_ONCE(tags->active_queues)); seq_puts(m, "\nbitmap_tags:\n"); sbitmap_queue_show(&tags->bitmap_tags, m); |