I see. would it be possible to detach the elevator from the queue in
elevator_exit instead?
On 6/17/2025 3:25 PM, Bart Van Assche wrote:
On 6/17/25 1:56 PM, Elijah Wright wrote:
in dd_finish_request(), per_prio points to a rq->elv.priv[0], which
could be
free memory if an in-flight requests completes after its associated
scheduler
has been freed
Signed-off-by: Elijah Wright <git@elijahs.space>
---
block/mq-deadline.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 2edf1cac06d5..4d7b21b144d3 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -751,13 +751,15 @@ static void dd_finish_request(struct request *rq)
{
struct dd_per_prio *per_prio = rq->elv.priv[0];
- /*
- * The block layer core may call dd_finish_request() without having
- * called dd_insert_requests(). Skip requests that bypassed I/O
- * scheduling. See also blk_mq_request_bypass_insert().
- */
- if (per_prio)
- atomic_inc(&per_prio->stats.completed);
+ if (rq->q->elevator) {
+ /*
+ * The block layer core may call dd_finish_request() without
having
+ * called dd_insert_requests(). Skip requests that bypassed I/O
+ * scheduling. See also blk_mq_request_bypass_insert().
+ */
+ if (per_prio)
+ atomic_inc(&per_prio->stats.completed);
+ }
}
The warnings in dd_exit_sched() will be triggered if dd_finish_request()
is ever called with rq->q->elevator == NULL.
If this can happen, it should be fixed in the block layer core instead
of in the mq-deadline scheduler.
Thanks,
Bart.
