From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EF2D7361DB8 for ; Thu, 25 Jun 2026 06:28:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782368917; cv=none; b=iXI7JuTlznwsZyqONT9evQXzl423GR00qfdYSauxc81aRCBygytoPMaH2gjHC8jyQNoBShhU7dC7jjgkulvQdZFk/s3Wekg5MMqvimakeuw5nDpB3Jx3+OSYv+wYgDSbKXBBq1y1t/nb/e0Vsjk/1MwGs+7OWYjBBSa2LDjRHH4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782368917; c=relaxed/simple; bh=weA2LuMovSjALg3d/e8Ous4vUMMaJRDM7wu6fOJlfaQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=nKH6m43UJim3lkrM8or2lP8H8j2nJ5wvEWZ365+F1cdzQDNCa7+0wNAMhDDSM9y3KXbVY/W+TWQbqpXZw/sRQbxviWzRKg4WBdT4tV9M0xUOdv/QElHKqxIV3nAhSvniSTpySXvGMHCsFhfcNpcg2MhElvdSNit69hOBIIVHSRc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D0AjBNiu; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D0AjBNiu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 653C41F000E9; Thu, 25 Jun 2026 06:28:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782368915; bh=Mpm1vBe/X/KrMUhOUQKcILpXvyLxHuF8R/Qa1fsWDCU=; h=From:To:Cc:Subject:Date; b=D0AjBNiuUQEvjRp8qDdGPf/jhb89824y0F0lzD/6LgW+gfqlccAOAkwYzw3JPU3S8 6ZoQ0wUWrXbU+3CuFUHWm21zskMRC9a00QKnxFlgOggAV0GmeC/wyUVkP6gpgguRer dYyknrWSnHRpmNUaIZj6brvpU+++dbkRBo3m9s9XnGBUdB0CKPGkXYVkX3Ao9cDKaR i+BzBcirZlEuBJ3KV9DBabXblTTAfXAO2v5hjfn1wG9zcIBfhbYJJtzOhgYzXQhcIJ QxFnOPS4GUK9/SeLg3Q/PYU4iHbXF8AL6dowNRaLEIjUW/oOgV/D95ay122lzOV231 GC0cOL26kH34w== From: Damien Le Moal To: Jens Axboe , linux-block@vger.kernel.org Cc: Christoph Hellwig Subject: [PATCH] block: avoid potential deadlock on zone revalidation failure Date: Thu, 25 Jun 2026 15:28:24 +0900 Message-ID: <20260625062824.2013244-1-dlemoal@kernel.org> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit If revalidating the zones of a zoned block device with blk_revalidate_disk_zones() fails during a SCSI disk rescan, the following lockdep splat is thrown: [ 347.251859] [ T11230] sda: failed to revalidate zones [ 347.261380] [ T11230] ====================================================== [ 347.263882] [ T11230] WARNING: possible circular locking dependency detected [ 347.266353] [ T11230] 7.1.0+ #1194 Not tainted [ 347.268052] [ T11230] ------------------------------------------------------ [ 347.270537] [ T11230] tcsh/11230 is trying to acquire lock: [ 347.272555] [ T11230] ffffffff8f91d400 (wq_pool_mutex){+.+.}-{4:4}, at: destroy_workqueue+0x15d/0x8d0 [ 347.275914] [ T11230] but task is already holding lock: [ 347.278646] [ T11230] ffff88812fa1bcc0 (&q->q_usage_counter(io)#5){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x16/0x30 [ 347.282503] [ T11230] which lock already depends on the new lock. [ 347.286239] [ T11230] the existing dependency chain (in reverse order) is: [ 347.289408] [ T11230] -> #2 (&q->q_usage_counter(io)#5){++++}-{0:0}: [ 347.292437] [ T11230] blk_alloc_queue+0x5ca/0x750 [ 347.294379] [ T11230] blk_mq_alloc_queue+0x14c/0x240 [ 347.296375] [ T11230] scsi_alloc_sdev+0x871/0xd10 [scsi_mod] [ 347.298619] [ T11230] scsi_probe_and_add_lun+0x600/0xc50 [scsi_mod] [ 347.301056] [ T11230] __scsi_scan_target+0x187/0x3b0 [scsi_mod] [ 347.303385] [ T11230] scsi_scan_channel+0xf2/0x180 [scsi_mod] [ 347.305651] [ T11230] scsi_scan_host_selected+0x20b/0x2d0 [scsi_mod] [ 347.308119] [ T11230] do_scan_async+0x42/0x420 [scsi_mod] [ 347.310276] [ T11230] async_run_entry_fn+0x94/0x5a0 [ 347.312284] [ T11230] process_one_work+0x8da/0x1690 [ 347.314287] [ T11230] worker_thread+0x5fe/0x1010 [ 347.316216] [ T11230] kthread+0x358/0x450 [ 347.317675] [ T11230] ret_from_fork+0x5b9/0x8e0 [ 347.319181] [ T11230] ret_from_fork_asm+0x11/0x20 [ 347.320778] [ T11230] -> #1 (fs_reclaim){+.+.}-{0:0}: [ 347.322890] [ T11230] fs_reclaim_acquire+0xd5/0x120 [ 347.324464] [ T11230] __kmalloc_cache_node_noprof+0x39/0x620 [ 347.326223] [ T11230] init_rescuer+0x19b/0x560 [ 347.327697] [ T11230] workqueue_init+0x33b/0x6a0 [ 347.329224] [ T11230] kernel_init_freeable+0x2eb/0x600 [ 347.330881] [ T11230] kernel_init+0x1c/0x140 [ 347.332334] [ T11230] ret_from_fork+0x5b9/0x8e0 [ 347.333847] [ T11230] ret_from_fork_asm+0x11/0x20 [ 347.335360] [ T11230] -> #0 (wq_pool_mutex){+.+.}-{4:4}: [ 347.337510] [ T11230] __lock_acquire+0xdea/0x2260 [ 347.339030] [ T11230] lock_acquire+0x187/0x2f0 [ 347.340495] [ T11230] __mutex_lock+0x1ab/0x2600 [ 347.341464] [ T11230] destroy_workqueue+0x15d/0x8d0 [ 347.342485] [ T11230] disk_free_zone_resources+0xd5/0x560 [ 347.343577] [ T11230] blk_revalidate_disk_zones+0x620/0xac7 [ 347.344723] [ T11230] sd_zbc_revalidate_zones+0x1dd/0x790 [sd_mod] [ 347.345938] [ T11230] sd_revalidate_disk+0xc66/0x8e60 [sd_mod] [ 347.347112] [ T11230] scsi_rescan_device+0x1f9/0x310 [scsi_mod] [ 347.348318] [ T11230] store_rescan_field+0x19/0x20 [scsi_mod] [ 347.349507] [ T11230] kernfs_fop_write_iter+0x3d2/0x5e0 [ 347.350565] [ T11230] vfs_write+0x469/0x1000 [ 347.351484] [ T11230] ksys_write+0x116/0x250 [ 347.352403] [ T11230] do_syscall_64+0xf0/0x6e0 [ 347.353361] [ T11230] entry_SYSCALL_64_after_hwframe+0x4b/0x53 [ 347.354533] [ T11230] other info that might help us debug this: [ 347.356432] [ T11230] Chain exists of: wq_pool_mutex --> fs_reclaim --> &q->q_usage_counter(io)#5 [ 347.358919] [ T11230] Possible unsafe locking scenario: [ 347.360307] [ T11230] CPU0 CPU1 [ 347.361327] [ T11230] ---- ---- [ 347.362340] [ T11230] lock(&q->q_usage_counter(io)#5); [ 347.363344] [ T11230] lock(fs_reclaim); [ 347.364526] [ T11230] lock(&q->q_usage_counter(io)#5); [ 347.365968] [ T11230] lock(wq_pool_mutex); [ 347.366811] [ T11230] *** DEADLOCK *** This happens because SCSI disk rescan is executed from a work context and a failure of blk_revalidate_disk_zones() causes a call to disk_free_zone_resources() which will free the disk zone write plug workqueue. Avoid this by delaying the destruction of the disk zone write plug workqueue to disk_release(). Do this by introducing the function disk_release_zone_resources() and using this new function from disk_release(). This new function calls disk_free_zone_resources() and destroys the zone write plugs workqueue, thus allowing to remove the call to destroy_workqueue() from disk_free_zone_resources(). disk_alloc_zone_resources() is modified to not create the disk zone write plug work queue if it already exists. Fixes: a8f59e5a5dea ("block: use a per disk workqueue for zone write plugging") Cc: stable@vger.kernek.org Signed-off-by: Damien Le Moal --- block/blk-zoned.c | 40 +++++++++++++++++++++++++--------------- block/blk.h | 4 ++-- block/genhd.c | 2 +- 3 files changed, 28 insertions(+), 18 deletions(-) diff --git a/block/blk-zoned.c b/block/blk-zoned.c index bea817f3de56..133600ebe05c 100644 --- a/block/blk-zoned.c +++ b/block/blk-zoned.c @@ -1923,11 +1923,20 @@ static int disk_alloc_zone_resources(struct gendisk *disk, if (!disk->zone_wplugs_pool) goto free_hash; - disk->zone_wplugs_wq = - alloc_workqueue("%s_zwplugs", WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_PERCPU, - pool_size, disk->disk_name); - if (!disk->zone_wplugs_wq) - goto destroy_pool; + /* + * We may already have a zone write plug workqueue as this function may + * be called after disk_free_zone_resources(), which does not destroy + * the workqueue (the zone write plugs workqueue is destroyed at + * disk_release() time). + */ + if (!disk->zone_wplugs_wq) { + disk->zone_wplugs_wq = + alloc_workqueue("%s_zwplugs", + WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_PERCPU, + pool_size, disk->disk_name); + if (!disk->zone_wplugs_wq) + goto destroy_pool; + } disk->zone_wplugs_worker = kthread_create(disk_zone_wplugs_worker, disk, @@ -1935,15 +1944,12 @@ static int disk_alloc_zone_resources(struct gendisk *disk, if (IS_ERR(disk->zone_wplugs_worker)) { ret = PTR_ERR(disk->zone_wplugs_worker); disk->zone_wplugs_worker = NULL; - goto destroy_wq; + goto destroy_pool; } wake_up_process(disk->zone_wplugs_worker); return 0; -destroy_wq: - destroy_workqueue(disk->zone_wplugs_wq); - disk->zone_wplugs_wq = NULL; destroy_pool: mempool_destroy(disk->zone_wplugs_pool); disk->zone_wplugs_pool = NULL; @@ -1999,7 +2005,7 @@ static void disk_set_zones_cond_array(struct gendisk *disk, u8 *zones_cond) kfree_rcu_mightsleep(zones_cond); } -void disk_free_zone_resources(struct gendisk *disk) +static void disk_free_zone_resources(struct gendisk *disk) { if (disk->zone_wplugs_worker) { kthread_stop(disk->zone_wplugs_worker); @@ -2007,11 +2013,6 @@ void disk_free_zone_resources(struct gendisk *disk) } WARN_ON_ONCE(!list_empty(&disk->zone_wplugs_list)); - if (disk->zone_wplugs_wq) { - destroy_workqueue(disk->zone_wplugs_wq); - disk->zone_wplugs_wq = NULL; - } - disk_destroy_zone_wplugs_hash_table(disk); disk_set_zones_cond_array(disk, NULL); @@ -2020,6 +2021,15 @@ void disk_free_zone_resources(struct gendisk *disk) disk->nr_zones = 0; } +void disk_release_zone_resources(struct gendisk *disk) +{ + disk_free_zone_resources(disk); + if (disk->zone_wplugs_wq) { + destroy_workqueue(disk->zone_wplugs_wq); + disk->zone_wplugs_wq = NULL; + } +} + struct blk_revalidate_zone_args { struct gendisk *disk; u8 *zones_cond; diff --git a/block/blk.h b/block/blk.h index 25af8ac5ef0f..fb95d3c58950 100644 --- a/block/blk.h +++ b/block/blk.h @@ -528,7 +528,7 @@ static inline void ioc_clear_queue(struct request_queue *q) #ifdef CONFIG_BLK_DEV_ZONED void disk_init_zone_resources(struct gendisk *disk); -void disk_free_zone_resources(struct gendisk *disk); +void disk_release_zone_resources(struct gendisk *disk); static inline bool bio_zone_write_plugging(struct bio *bio) { return bio_flagged(bio, BIO_ZONE_WRITE_PLUGGING); @@ -581,7 +581,7 @@ int blkdev_zone_mgmt_ioctl(struct block_device *bdev, blk_mode_t mode, static inline void disk_init_zone_resources(struct gendisk *disk) { } -static inline void disk_free_zone_resources(struct gendisk *disk) +static inline void disk_release_zone_resources(struct gendisk *disk) { } static inline bool bio_zone_write_plugging(struct bio *bio) diff --git a/block/genhd.c b/block/genhd.c index f84b6a355b57..30ac0ffe6517 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1300,7 +1300,7 @@ static void disk_release(struct device *dev) disk_release_events(disk); kfree(disk->random); - disk_free_zone_resources(disk); + disk_release_zone_resources(disk); xa_destroy(&disk->part_tbl); kobject_put(&disk->queue_kobj); -- 2.54.0