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    Subject[PATCH 4.19 055/118] blk-mq: move cancel of requeue_work into blk_mq_release
    Date
    [ 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@oracle.com>
    Cc: James Smart <james.smart@broadcom.com>
    Cc: Bart Van Assche <bart.vanassche@wdc.com>
    Cc: linux-scsi@vger.kernel.org,
    Cc: Martin K . Petersen <martin.petersen@oracle.com>,
    Cc: Christoph Hellwig <hch@lst.de>,
    Cc: James E . J . Bottomley <jejb@linux.vnet.ibm.com>,
    Reviewed-by: Bart Van Assche <bvanassche@acm.org>
    Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
    Reviewed-by: Hannes Reinecke <hare@suse.com>
    Reviewed-by: Christoph Hellwig <hch@lst.de>
    Tested-by: James Smart <james.smart@broadcom.com>
    Signed-off-by: Ming Lei <ming.lei@redhat.com>
    Signed-off-by: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: Sasha Levin <sashal@kernel.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 33488b1426b7..6eed5d84c2ef 100644
    --- a/block/blk-core.c
    +++ b/block/blk-core.c
    @@ -411,7 +411,6 @@ 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);
    } else {
    diff --git a/block/blk-mq.c b/block/blk-mq.c
    index 4e563ee462cb..70d839b9c3b0 100644
    --- a/block/blk-mq.c
    +++ b/block/blk-mq.c
    @@ -2465,6 +2465,8 @@ 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


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