block: don't call rq_qos_ops->done_bio if the bio isn't tracked
authorMing Lei <ming.lei@redhat.com>
Fri, 24 Sep 2021 11:07:04 +0000 (19:07 +0800)
committerJens Axboe <axboe@kernel.dk>
Fri, 24 Sep 2021 17:04:39 +0000 (11:04 -0600)
commita647a524a46736786c95cdb553a070322ca096e3
tree9e521c7d5b50c6a8f708865d889ce7afc8d16aec
parent5cad87569164fbdd5279504d7bc089aea51bf0f4
block: don't call rq_qos_ops->done_bio if the bio isn't tracked

rq_qos framework is only applied on request based driver, so:

1) rq_qos_done_bio() needn't to be called for bio based driver

2) rq_qos_done_bio() needn't to be called for bio which isn't tracked,
such as bios ended from error handling code.

Especially in bio_endio():

1) request queue is referred via bio->bi_bdev->bd_disk->queue, which
may be gone since request queue refcount may not be held in above two
cases

2) q->rq_qos may be freed in blk_cleanup_queue() when calling into
__rq_qos_done_bio()

Fix the potential kernel panic by not calling rq_qos_ops->done_bio if
the bio isn't tracked. This way is safe because both ioc_rqos_done_bio()
and blkcg_iolatency_done_bio() are nop if the bio isn't tracked.

Reported-by: Yu Kuai <yukuai3@huawei.com>
Cc: tj@kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20210924110704.1541818-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block/bio.c