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Date:   Wed, 24 Apr 2019 18:18:56 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        Hannes Reinecke <hare@suse.com>,
        Keith Busch <keith.busch@intel.com>,
        linux-nvme@lists.infradead.org, Sagi Grimberg <sagi@grimberg.me>,
        James Smart <james.smart@broadcom.com>,
        Dongli Zhang <dongli.zhang@oracle.com>,
        Bart Van Assche <bart.vanassche@wdc.com>,
        linux-scsi@vger.kernel.org,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        Christoph Hellwig <hch@lst.de>,
        "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>
Subject: Re: [PATCH V7 2/9] blk-mq: move cancel of requeue_work into
 blk_mq_release
Message-ID: <20190424161856.GB23854@lst.de>
References: <20190424110221.17435-1-ming.lei@redhat.com> <20190424110221.17435-3-ming.lei@redhat.com>
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On Wed, Apr 24, 2019 at 07:02:14PM +0800, Ming Lei wrote:
> 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.

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

From mboxrd@z Thu Jan  1 00:00:00 1970
From: hch@lst.de (Christoph Hellwig)
Date: Wed, 24 Apr 2019 18:18:56 +0200
Subject: [PATCH V7 2/9] blk-mq: move cancel of requeue_work into
 blk_mq_release
In-Reply-To: <20190424110221.17435-3-ming.lei@redhat.com>
References: <20190424110221.17435-1-ming.lei@redhat.com>
 <20190424110221.17435-3-ming.lei@redhat.com>
Message-ID: <20190424161856.GB23854@lst.de>

On Wed, Apr 24, 2019@07:02:14PM +0800, Ming Lei wrote:
> 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.

Looks good,

Reviewed-by: Christoph Hellwig <hch at lst.de>