From: Yu Kuai <yukuai3@xxxxxxxxxx> commit 181490d5321806e537dc5386db5ea640b826bf78 upstream. If bfq_schedule_dispatch() is called from bfq_idle_slice_timer_body(), then 'bfqd->queued' is read without holding 'bfqd->lock'. This is wrong since it can be wrote concurrently. Fix the problem by holding 'bfqd->lock' in such case. Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220513023507.2625717-2-yukuai3@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Cc: Khazhy Kumykov <khazhy@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- block/bfq-iosched.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -298,6 +298,8 @@ static struct bfq_io_cq *bfq_bic_lookup( */ void bfq_schedule_dispatch(struct bfq_data *bfqd) { + lockdep_assert_held(&bfqd->lock); + if (bfqd->queued != 0) { bfq_log(bfqd, "schedule dispatch"); blk_mq_run_hw_queues(bfqd->queue, true); @@ -4584,8 +4586,8 @@ bfq_idle_slice_timer_body(struct bfq_dat bfq_bfqq_expire(bfqd, bfqq, true, reason); schedule_dispatch: - spin_unlock_irqrestore(&bfqd->lock, flags); bfq_schedule_dispatch(bfqd); + spin_unlock_irqrestore(&bfqd->lock, flags); } /*
