On Thu, Sep 23 2021 at 5:11P -0400,
Ming Lei <ming.lei@xxxxxxxxxx> wrote:
> DM uses blk-mq's quiesce/unquiesce to stop/start device mapper queue.
>
> But blk-mq's unquiesce may come from outside events, such as elevator
> switch, updating nr_requests or others, and request may come during
> suspend, so simply ask for blk-mq to requeue it.
>
> Fixes one kernel panic issue when running updating nr_requests and
> dm-mpath suspend/resume stress test.
>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> drivers/md/dm-rq.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
> index 5b95eea517d1..a896dea9750e 100644
> --- a/drivers/md/dm-rq.c
> +++ b/drivers/md/dm-rq.c
> @@ -490,6 +490,14 @@ static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
> struct mapped_device *md = tio->md;
> struct dm_target *ti = md->immutable_target;
>
> + /*
> + * blk-mq's unquiesce may come from outside events, such as
> + * elevator switch, updating nr_requests or others, and request may
> + * come during suspend, so simply ask for blk-mq to requeue it.
> + */
> + if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)))
> + return BLK_STS_RESOURCE;
> +
> if (unlikely(!ti)) {
> int srcu_idx;
> struct dm_table *map = dm_get_live_table(md, &srcu_idx);
> --
> 2.31.1
>
Hey Ming,
I've marked this for stable@ and queued this up. BUT this test is
racey, could easily be that device gets suspended just after your
test.
Mike
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