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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a0b8efb156sm22054562a91.1.2026.09.28.04.58.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2026 04:58:44 -0700 (PDT) From: Cong Zhang Date: Mon, 28 Sep 2026 19:58:38 +0800 Subject: [PATCH v3] virtio_blk: use synchronous quiesce in virtblk_freeze_priv() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260928-virtblk_sync_quiesce-v3-1-a037e6e2fdf5@oss.qualcomm.com> X-B4-Tracking: v=1; b=H4sIAG1WumoC/3WN3Q6CIACFX8VxHQ7wJ+yq92jNAWJSKgnKcs53D 2xtXdjN2c52zvctwEqjpAWnaAFGOmWV7n1JDhEQDetvEqrKd0AQyVGBEXTKjLx9lHbuRTlM/is kLDgRlFZpluIc+OvTyFq9Nuzl+ul24ncpxsAKi0bZUZt58zocdl8F3lc4DDFklCY1rRNMMnrW1 sbDxFqhuy72AYLJkV8W+cMinoUKhhDO0oIfyQ5rXdc3ejIhdB0BAAA= X-Change-ID: 20260910-virtblk_sync_quiesce-9b2c88d45416 To: "Michael S. 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The dispatcher checks QUEUE_FLAG_QUIESCED while the flag is clear. It can then be preempted before it gets a request. At that time, it has no queue usage reference, so blk_mq_freeze_queue() does not wait for it. virtblk_freeze_priv() then calls blk_mq_quiesce_queue_nowait() and blk_mq_unfreeze_queue(). A new request can enter the queue. The old dispatcher can run again, use its old flag check, get the new request, and call virtio_queue_rq(). At the same time, virtblk_freeze_priv() can reset the device, delete the virtqueues, and free vblk->vqs. The old dispatcher can then use a deleted virtqueue or a NULL vblk->vqs, and the kernel can crash. Fix this by using blk_mq_quiesce_queue(), which waits for dispatch code that was already running. Keep the existing freeze and unfreeze order. The queue remains quiesced until virtblk_restore_priv() calls blk_mq_unquiesce_queue(). Fixes: 7678abee0867 ("virtio-blk: don't keep queue frozen during system suspend") Cc: stable@vger.kernel.org Acked-by: Jason Wang Reviewed-by: Stefan Hajnoczi Signed-off-by: Cong Zhang --- Changes in v3: - Move the race description into the commit log. - Remove the blank line between tags. - Add Cc: stable@vger.kernel.org to the commit trailers. - Link to v2: https://lore.kernel.org/20260912-virtblk_sync_quiesce-v2-1-09a001549b72@oss.qualcomm.com Changes in v2: - Cc stable@vger.kernel.org. - Link to v1: https://lore.kernel.org/20260911-virtblk_sync_quiesce-v1-1-a883f8f31258@oss.qualcomm.com --- drivers/block/virtio_blk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 32bf3ba07a9d..7a570591e040 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -1595,7 +1595,7 @@ static int virtblk_freeze_priv(struct virtio_device *vdev) /* Ensure no requests in virtqueues before deleting vqs. */ memflags = blk_mq_freeze_queue(q); - blk_mq_quiesce_queue_nowait(q); + blk_mq_quiesce_queue(q); blk_mq_unfreeze_queue(q, memflags); /* Ensure we don't receive any more interrupts */ --- base-commit: 50d05c7c76c96b90462f24debacca971d2e86713 change-id: 20260910-virtblk_sync_quiesce-9b2c88d45416 Best regards, -- Cong Zhang