linux-kernel - [PATCH 5.1 070/155] blk-mq: move cancel of requeue_work into blk_mq

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Message-Id: <20190613075656.897201625@linuxfoundation.org>
Date:   Thu, 13 Jun 2019 10:33:02 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dongli Zhang <dongli.zhang@...cle.com>,
        James Smart <james.smart@...adcom.com>,
        Bart Van Assche <bart.vanassche@....com>,
        Bart Van Assche <bvanassche@....org>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        Hannes Reinecke <hare@...e.com>,
        Christoph Hellwig <hch@....de>, Ming Lei <ming.lei@...hat.com>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>,
        linux-scsi@...r.kernel.org,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        "James E . J . Bottomley" <jejb@...ux.vnet.ibm.com>
Subject: [PATCH 5.1 070/155] blk-mq: move cancel of requeue_work into blk_mq_release

[ Upstream commit fbc2a15e3433058582e5635aabe48a3011a644a8 ]

With holding queue's kobject refcount, it is safe for driver
to schedule requeue. However, blk_mq_kick_requeue_list() may
be called after blk_sync_queue() is done because of concurrent
requeue activities, then requeue work may not be completed when
freeing queue, and kernel oops is triggered.

So moving the cancel of requeue_work into blk_mq_release() for
avoiding race between requeue and freeing queue.

Cc: Dongli Zhang <dongli.zhang@...cle.com>
Cc: James Smart <james.smart@...adcom.com>
Cc: Bart Van Assche <bart.vanassche@....com>
Cc: linux-scsi@...r.kernel.org,
Cc: Martin K . Petersen <martin.petersen@...cle.com>,
Cc: Christoph Hellwig <hch@....de>,
Cc: James E . J . Bottomley <jejb@...ux.vnet.ibm.com>,
Reviewed-by: Bart Van Assche <bvanassche@....org>
Reviewed-by: Johannes Thumshirn <jthumshirn@...e.de>
Reviewed-by: Hannes Reinecke <hare@...e.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Tested-by: James Smart <james.smart@...adcom.com>
Signed-off-by: Ming Lei <ming.lei@...hat.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 block/blk-core.c | 1 -
 block/blk-mq.c   | 2 ++
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index b375cfea024c..2dd94b3e9ece 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -237,7 +237,6 @@ void blk_sync_queue(struct request_queue *q)
 		struct blk_mq_hw_ctx *hctx;
 		int i;
 
-		cancel_delayed_work_sync(&q->requeue_work);
 		queue_for_each_hw_ctx(q, hctx, i)
 			cancel_delayed_work_sync(&hctx->run_work);
 	}
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 8a41cc5974fe..11efca3534ad 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2666,6 +2666,8 @@ void blk_mq_release(struct request_queue *q)
 	struct blk_mq_hw_ctx *hctx;
 	unsigned int i;
 
+	cancel_delayed_work_sync(&q->requeue_work);
+
 	/* hctx kobj stays in hctx */
 	queue_for_each_hw_ctx(q, hctx, i) {
 		if (!hctx)
-- 
2.20.1