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Tue, 01 Sep 2026 05:24:19 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Stanley Jhu Date: Tue, 1 Sep 2026 20:23:43 +0800 X-Gm-Features: AcwNN1WE8g6tSRs53V9lxDRCC9ypyaxRDWe_obKQX3VLlFgTm5cLh0_k_iVI3WQ Message-ID: Subject: [PATCH] scsi: core: Set BLK_FEAT_SKIP_TAGSET_QUIESCE on pseudo SCSI devices To: "James E . J . Bottomley" , "Martin K . Petersen" Cc: Bart Van Assche , hare@suse.de, john.g.garry@oracle.com, hch@lst.de, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Commit d630fbf6fc8c ("scsi: core: Support allocating a pseudo SCSI device") introduced pseudo SCSI devices to allocate and dispatch internal SCSI commands (such as device management commands) via scsi_get_internal_cmd(). Subsequently, commit 08b12cda6c44 ("scsi: ufs: core: Switch to scsi_get_internal_cmd()") switched UFS internal commands to use this mechanism. However, pseudo SCSI devices share the host tagset (&shost->tag_set) with regular LUNs. During error recovery or host reset, drivers typically quiesce the host tagset via blk_mq_quiesce_tagset(&shost->tag_set) to freeze user block I/O. Because pseudo_sdev->request_queue belongs to shost->tag_set, blk_mq_quiesce_tagset() marks it QUEUE_FLAG_QUIESCED as well. When error handling then attempts to issue internal commands to recover or verify the device (e.g. ufshcd_verify_dev_init() issuing a NOP OUT UPIU), blk_execute_rq() inserts the request into the request_queue of pseudo_sdev. Because the queue is quiesced, blk_mq_run_hw_queue() skips running the queue, and blk_execute_rq() blocks indefinitely waiting for completion. Since blk_mq_unquiesce_tagset() is only invoked after error recovery finishes, this results in an unrecoverable circular wait deadlock. Resolve this by setting BLK_FEAT_SKIP_TAGSET_QUIESCE in struct queue_limits when allocating a pseudo SCSI device in scsi_alloc_sdev(). Passing this feature directly into blk_mq_alloc_queue() conforms to the Block Layer's atomic queue limits initialization model and mirrors NVMe's canonical pattern for its internal connect_q in drivers/nvme/host/core.c. This ensures that blk_mq_quiesce_tagset() ignores the pseudo device's request queue, allowing internal commands to be dispatched while user I/O remains quiesced. Fixes: d630fbf6fc8c ("scsi: core: Support allocating a pseudo SCSI device") Fixes: 08b12cda6c44 ("scsi: ufs: core: Switch to scsi_get_internal_cmd()") Cc: stable@vger.kernel.org Signed-off-by: Stanley Jhu --- drivers/scsi/scsi_scan.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 3b82e80e807a..eb48866ed0dc 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -336,6 +336,8 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget, sdev->sg_reserved_size =3D INT_MAX; scsi_init_limits(shost, &lim); + if (scsi_device_is_pseudo_dev(sdev)) + lim.features |=3D BLK_FEAT_SKIP_TAGSET_QUIESCE; q =3D blk_mq_alloc_queue(&sdev->host->tag_set, &lim, sdev); if (IS_ERR(q)) { /* release fn is set up in scsi_sysfs_device_initialise, so -- 2.43.0