diff options
| author | Ming Lei <ming.lei@redhat.com> | 2026-01-22 12:28:58 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-01-22 07:24:17 -0700 |
| commit | 046be7e5967ef80547f7fd8a399e932f5338d5d4 (patch) | |
| tree | 23af70912c444be1204d54696ec2575a65dbedef /block | |
| parent | e7e1cc18f120a415646be12470169a978a1adcd9 (diff) | |
blk-mq: use BLK_POLL_ONESHOT for synchronous poll completion
blk_execute_rq() with polling is used in kernel code paths such as
NVMe controller connect. The aggressive spinning in blk_hctx_poll()
can prevent the completion task from getting a chance to run, causing
a lockup.
The spinning with cpu_relax() doesn't yield CPU, so need_resched()
only becomes true on timer tick. This causes unnecessary spinning
while the completion task is already waiting to run.
Before commit f22ecf9c14c1, the loop would exit early because
task_is_running() was always true. After that commit removed the
check, the loop now spins until need_resched().
Fix this by using BLK_POLL_ONESHOT in blk_rq_poll_completion(). This
causes blk_hctx_poll() to poll once and return immediately, letting
the outer loop's cond_resched() yield CPU so the completion task can
run.
Fixes: f22ecf9c14c1 ("blk-mq: delete task running check in blk_hctx_poll()")
Cc: Diangang Li <lidiangang@bytedance.com>
Cc: Fengnan Chang <changfengnan@bytedance.com>
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-mq.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index a29d8ac9d3e3..968699277c3d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1480,7 +1480,7 @@ EXPORT_SYMBOL_GPL(blk_rq_is_poll); static void blk_rq_poll_completion(struct request *rq, struct completion *wait) { do { - blk_hctx_poll(rq->q, rq->mq_hctx, NULL, 0); + blk_hctx_poll(rq->q, rq->mq_hctx, NULL, BLK_POLL_ONESHOT); cond_resched(); } while (!completion_done(wait)); } |