diff mbox

block: do not put mq context in blk_mq_alloc_request_hctx

Message ID 1490851245-32245-1-git-send-email-minchan@kernel.org (mailing list archive)
State New, archived
Headers show

Commit Message

Minchan Kim March 30, 2017, 5:20 a.m. UTC
In blk_mq_alloc_request_hctx, blk_mq_sched_get_request doesn't
get sw context so we don't need to put the context with
blk_mq_put_ctx. Unless, we will see preempt counter underflow.

Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---

Maybe, it would be fixed by someone but I have noticed preempt counter
undeflow problem a few weeks ago and still see the problem with
linux-next.

 block/blk-mq.c | 1 -
 1 file changed, 1 deletion(-)

Comments

Sagi Grimberg March 30, 2017, 2:02 p.m. UTC | #1
Looks good,

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Jens Axboe March 30, 2017, 2:12 p.m. UTC | #2
On 03/29/2017 11:20 PM, Minchan Kim wrote:
> In blk_mq_alloc_request_hctx, blk_mq_sched_get_request doesn't
> get sw context so we don't need to put the context with
> blk_mq_put_ctx. Unless, we will see preempt counter underflow.

Good catch, that's definitely a bug. I have applied your patch
for 4.11.
diff mbox

Patch

diff --git a/block/blk-mq.c b/block/blk-mq.c
index a4546f060e80..a6f3998dc4ee 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -321,7 +321,6 @@  struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
 
 	rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
 
-	blk_mq_put_ctx(alloc_data.ctx);
 	blk_queue_exit(q);
 
 	if (!rq)