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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Anton Ivanov <anton.ivanov@cambridgegreys.com>,
        Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 5.3 121/163] um-ubd: Entrust re-queue to the upper layers
Date:   Mon,  4 Nov 2019 22:45:11 +0100
Message-Id: <20191104212148.975125444@linuxfoundation.org>
In-Reply-To: <20191104212140.046021995@linuxfoundation.org>
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From: Anton Ivanov <anton.ivanov@cambridgegreys.com>

commit d848074b2f1eb11a38691285f7366bce83087014 upstream.

Fixes crashes due to ubd requeue logic conflicting with the block-mq
logic. Crash is reproducible in 5.0 - 5.3.

Fixes: 53766defb8c8 ("um: Clean-up command processing in UML UBD driver")
Cc: stable@vger.kernel.org # v5.0+
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/um/drivers/ubd_kern.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -1403,8 +1403,12 @@ static blk_status_t ubd_queue_rq(struct
 
 	spin_unlock_irq(&ubd_dev->lock);
 
-	if (ret < 0)
-		blk_mq_requeue_request(req, true);
+	if (ret < 0) {
+		if (ret == -ENOMEM)
+			res = BLK_STS_RESOURCE;
+		else
+			res = BLK_STS_DEV_RESOURCE;
+	}
 
 	return res;
 }