On 2020-04-16 04:18, John Garry wrote:
If in blk_mq_dispatch_rq_list() we find no budget, then we break of the
dispatch loop, but the request may keep the driver tag, evaulated
in 'nxt' in the previous loop iteration.
Fix by putting the driver tag for that request.
Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 8e56884fd2e9..a7785df2c944 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1222,8 +1222,10 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
rq = list_first_entry(list, struct request, queuelist);
hctx = rq->mq_hctx;
- if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
+ if (!got_budget && !blk_mq_get_dispatch_budget(hctx)) {
+ blk_mq_put_driver_tag(rq);
break;
+ }
if (!blk_mq_get_driver_tag(rq)) {
/*
Is this something that can only happen if q->mq_ops->queue_rq(hctx, &bd)
returns another value than BLK_STS_OK, BLK_STS_RESOURCE and
BLK_STS_DEV_RESOURCE?
that explains this.
Is this perhaps a bug fix for 0bca799b9280 ("blk-mq: order getting
budget and driver tag")? If so, please mention this and add Cc tags for
the people who were Cc-ed on that patch.