kernel/linux.git/block, branch v6.6.131

blk-mq-debugfs: add missing debugfs_mutex in blk_mq_debugfs_register_hctxs()

2026-03-04T12:20:35+00:00

[ Upstream commit 9d20fd6ce1ba9733cd5ac96fcab32faa9fc404dd ] In blk_mq_update_nr_hw_queues(), debugfs_mutex is not held while creating debugfs entries for hctxs. Hence add debugfs_mutex there, it's safe because queue is not frozen. Signed-off-by: Yu Kuai Reviewed-by: Nilay Shroff Reviewed-by: Ming Lei Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

block,bfq: fix aux stat accumulation destination

2026-02-11T12:39:10+00:00

[ Upstream commit 04bdb1a04d8a2a89df504c1e34250cd3c6e31a1c ] Route bfqg_stats_add_aux() time accumulation into the destination stats object instead of the source, aligning with other stat fields. Reviewed-by: Yu Kuai Signed-off-by: shechenglong Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

blk-mq: setup queue ->tag_set before initializing hctx

2026-01-11T14:22:33+00:00

commit c25c0c9035bb8b28c844dfddeda7b8bdbcfcae95 upstream. Commit 7b815817aa58 ("blk-mq: add helper for checking if one CPU is mapped to specified hctx") needs to check queue mapping via tag set in hctx's cpuhp handler. However, q->tag_set may not be setup yet when the cpuhp handler is enabled, then kernel oops is triggered. Fix the issue by setup queue tag_set before initializing hctx. Cc: stable@vger.kernel.org Reported-and-tested-by: Rick Koch Closes: https://lore.kernel.org/linux-block/CANa58eeNDozLaBHKPLxSAhEy__FPfJT_F71W=sEQw49UCrC9PQ@mail.gmail.com Fixes: 7b815817aa58 ("blk-mq: add helper for checking if one CPU is mapped to specified hctx") Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Reviewed-by: John Garry Link: https://lore.kernel.org/r/20241014005115.2699642-1-ming.lei@redhat.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

blk-mq: add helper for checking if one CPU is mapped to specified hctx

2026-01-11T14:22:20+00:00

commit 7b815817aa58d2e2101feb2fcf64c60cae0b2695 upstream. Commit a46c27026da1 ("blk-mq: don't schedule block kworker on isolated CPUs") rules out isolated CPUs from hctx->cpumask, and hctx->cpumask should only be used for scheduling kworker. Add helper blk_mq_cpu_mapped_to_hctx() and apply it into cpuhp handlers. This patch avoids to forget clearing INACTIVE of hctx state in case that one isolated CPU becomes online, and fixes hang issue when allocating request from this hctx's tags. Cc: Raju Cheerla Fixes: a46c27026da1 ("blk-mq: don't schedule block kworker on isolated CPUs") Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20240517020514.149771-1-ming.lei@redhat.com Tested-by: Raju Cheerla Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

blk-mq: skip CPU offline notify on unmapped hctx

2026-01-11T14:22:09+00:00

[ Upstream commit 10845a105bbcb030647a729f1716c2309da71d33 ] If an hctx has no software ctx mapped, blk_mq_map_swqueue() never allocates tags and leaves hctx->tags NULL. The CPU hotplug offline notifier can still run for that hctx, return early since hctx cannot hold any requests. Signed-off-by: Cong Zhang Fixes: bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are offline") Reviewed-by: Ming Lei Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

blk-mq: don't schedule block kworker on isolated CPUs

2026-01-11T14:22:09+00:00

[ Upstream commit a46c27026da10a126dd870f7b65380010bd20db5 ] Kernel parameter of `isolcpus=` or 'nohz_full=' are used to isolate CPUs for specific task, and it isn't expected to let block IO disturb these CPUs. blk-mq kworker shouldn't be scheduled on isolated CPUs. Also if isolated CPUs is run for blk-mq kworker, long block IO latency can be caused. Kernel workqueue only respects CPU isolation for WQ_UNBOUND, for bound WQ, the responsibility is on user because CPU is specified as WQ API parameter, such as mod_delayed_work_on(cpu), queue_delayed_work_on(cpu) and queue_work_on(cpu). So not run blk-mq kworker on isolated CPUs by removing isolated CPUs from hctx->cpumask. Meantime use queue map to check if all CPUs in this hw queue are offline instead of hctx->cpumask, this way can avoid any cost in fast IO code path, and is safe since hctx->cpumask are only used in the two cases. Cc: Tim Chen Cc: Juri Lelli Cc: Andrew Theurer Cc: Joe Mario Cc: Sebastian Jug Cc: Frederic Weisbecker Cc: Bart Van Assche Cc: Tejun Heo Tesed-by: Joe Mario Signed-off-by: Ming Lei Reviewed-by: Ewan D. Milne Link: https://lore.kernel.org/r/20240322021244.1056223-1-ming.lei@redhat.com Signed-off-by: Jens Axboe Stable-dep-of: 10845a105bbc ("blk-mq: skip CPU offline notify on unmapped hctx") Signed-off-by: Sasha Levin

block: rate-limit capacity change info log

2026-01-11T14:21:55+00:00

commit 3179a5f7f86bcc3acd5d6fb2a29f891ef5615852 upstream. loop devices under heavy stress-ng loop streessor can trigger many capacity change events in a short time. Each event prints an info message from set_capacity_and_notify(), flooding the console and contributing to soft lockups on slow consoles. Switch the printk in set_capacity_and_notify() to pr_info_ratelimited() so frequent capacity changes do not spam the log while still reporting occasional changes. Cc: stable@vger.kernel.org Signed-off-by: Li Chen Reviewed-by: Chaitanya Kulkarni Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

block: Use RCU in blk_mq_[un]quiesce_tagset() instead of set->tag_list_lock

2026-01-11T14:21:39+00:00

[ Upstream commit 59e25ef2b413c72da6686d431e7759302cfccafa ] blk_mq_{add,del}_queue_tag_set() functions add and remove queues from tagset, the functions make sure that tagset and queues are marked as shared when two or more queues are attached to the same tagset. Initially a tagset starts as unshared and when the number of added queues reaches two, blk_mq_add_queue_tag_set() marks it as shared along with all the queues attached to it. When the number of attached queues drops to 1 blk_mq_del_queue_tag_set() need to mark both the tagset and the remaining queues as unshared. Both functions need to freeze current queues in tagset before setting on unsetting BLK_MQ_F_TAG_QUEUE_SHARED flag. While doing so, both functions hold set->tag_list_lock mutex, which makes sense as we do not want queues to be added or deleted in the process. This used to work fine until commit 98d81f0df70c ("nvme: use blk_mq_[un]quiesce_tagset") made the nvme driver quiesce tagset instead of quiscing individual queues. blk_mq_quiesce_tagset() does the job and quiesce the queues in set->tag_list while holding set->tag_list_lock also. This results in deadlock between two threads with these stacktraces: __schedule+0x47c/0xbb0 ? timerqueue_add+0x66/0xb0 schedule+0x1c/0xa0 schedule_preempt_disabled+0xa/0x10 __mutex_lock.constprop.0+0x271/0x600 blk_mq_quiesce_tagset+0x25/0xc0 nvme_dev_disable+0x9c/0x250 nvme_timeout+0x1fc/0x520 blk_mq_handle_expired+0x5c/0x90 bt_iter+0x7e/0x90 blk_mq_queue_tag_busy_iter+0x27e/0x550 ? __blk_mq_complete_request_remote+0x10/0x10 ? __blk_mq_complete_request_remote+0x10/0x10 ? __call_rcu_common.constprop.0+0x1c0/0x210 blk_mq_timeout_work+0x12d/0x170 process_one_work+0x12e/0x2d0 worker_thread+0x288/0x3a0 ? rescuer_thread+0x480/0x480 kthread+0xb8/0xe0 ? kthread_park+0x80/0x80 ret_from_fork+0x2d/0x50 ? kthread_park+0x80/0x80 ret_from_fork_asm+0x11/0x20 __schedule+0x47c/0xbb0 ? xas_find+0x161/0x1a0 schedule+0x1c/0xa0 blk_mq_freeze_queue_wait+0x3d/0x70 ? destroy_sched_domains_rcu+0x30/0x30 blk_mq_update_tag_set_shared+0x44/0x80 blk_mq_exit_queue+0x141/0x150 del_gendisk+0x25a/0x2d0 nvme_ns_remove+0xc9/0x170 nvme_remove_namespaces+0xc7/0x100 nvme_remove+0x62/0x150 pci_device_remove+0x23/0x60 device_release_driver_internal+0x159/0x200 unbind_store+0x99/0xa0 kernfs_fop_write_iter+0x112/0x1e0 vfs_write+0x2b1/0x3d0 ksys_write+0x4e/0xb0 do_syscall_64+0x5b/0x160 entry_SYSCALL_64_after_hwframe+0x4b/0x53 The top stacktrace is showing nvme_timeout() called to handle nvme command timeout. timeout handler is trying to disable the controller and as a first step, it needs to blk_mq_quiesce_tagset() to tell blk-mq not to call queue callback handlers. The thread is stuck waiting for set->tag_list_lock as it tries to walk the queues in set->tag_list. The lock is held by the second thread in the bottom stack which is waiting for one of queues to be frozen. The queue usage counter will drop to zero after nvme_timeout() finishes, and this will not happen because the thread will wait for this mutex forever. Given that [un]quiescing queue is an operation that does not need to sleep, update blk_mq_[un]quiesce_tagset() to use RCU instead of taking set->tag_list_lock, update blk_mq_{add,del}_queue_tag_set() to use RCU safe list operations. Also, delete INIT_LIST_HEAD(&q->tag_set_list) in blk_mq_del_queue_tag_set() because we can not re-initialize it while the list is being traversed under RCU. The deleted queue will not be added/deleted to/from a tagset and it will be freed in blk_free_queue() after the end of RCU grace period. Signed-off-by: Mohamed Khalfella Fixes: 98d81f0df70c ("nvme: use blk_mq_[un]quiesce_tagset") Reviewed-by: Ming Lei Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

blk-mq: Abort suspend when wakeup events are pending

2026-01-11T14:21:38+00:00

[ Upstream commit c196bf43d706592d8801a7513603765080e495fb ] During system suspend, wakeup capable IRQs for block device can be delayed, which can cause blk_mq_hctx_notify_offline() to hang indefinitely while waiting for pending request to complete. Skip the request waiting loop and abort suspend when wakeup events are pending to prevent the deadlock. Fixes: bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are offline") Signed-off-by: Cong Zhang Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

blk-cgroup: fix possible deadlock while configuring policy

2025-11-24T09:29:22+00:00

[ Upstream commit 5d726c4dbeeddef612e6bed27edd29733f4d13af ] Following deadlock can be triggered easily by lockdep: WARNING: possible circular locking dependency detected 6.17.0-rc3-00124-ga12c2658ced0 #1665 Not tainted ------------------------------------------------------ check/1334 is trying to acquire lock: ff1100011d9d0678 (&q->sysfs_lock){+.+.}-{4:4}, at: blk_unregister_queue+0x53/0x180 but task is already holding lock: ff1100011d9d00e0 (&q->q_usage_counter(queue)#3){++++}-{0:0}, at: del_gendisk+0xba/0x110 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&q->q_usage_counter(queue)#3){++++}-{0:0}: blk_queue_enter+0x40b/0x470 blkg_conf_prep+0x7b/0x3c0 tg_set_limit+0x10a/0x3e0 cgroup_file_write+0xc6/0x420 kernfs_fop_write_iter+0x189/0x280 vfs_write+0x256/0x490 ksys_write+0x83/0x190 __x64_sys_write+0x21/0x30 x64_sys_call+0x4608/0x4630 do_syscall_64+0xdb/0x6b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #1 (&q->rq_qos_mutex){+.+.}-{4:4}: __mutex_lock+0xd8/0xf50 mutex_lock_nested+0x2b/0x40 wbt_init+0x17e/0x280 wbt_enable_default+0xe9/0x140 blk_register_queue+0x1da/0x2e0 __add_disk+0x38c/0x5d0 add_disk_fwnode+0x89/0x250 device_add_disk+0x18/0x30 virtblk_probe+0x13a3/0x1800 virtio_dev_probe+0x389/0x610 really_probe+0x136/0x620 __driver_probe_device+0xb3/0x230 driver_probe_device+0x2f/0xe0 __driver_attach+0x158/0x250 bus_for_each_dev+0xa9/0x130 driver_attach+0x26/0x40 bus_add_driver+0x178/0x3d0 driver_register+0x7d/0x1c0 __register_virtio_driver+0x2c/0x60 virtio_blk_init+0x6f/0xe0 do_one_initcall+0x94/0x540 kernel_init_freeable+0x56a/0x7b0 kernel_init+0x2b/0x270 ret_from_fork+0x268/0x4c0 ret_from_fork_asm+0x1a/0x30 -> #0 (&q->sysfs_lock){+.+.}-{4:4}: __lock_acquire+0x1835/0x2940 lock_acquire+0xf9/0x450 __mutex_lock+0xd8/0xf50 mutex_lock_nested+0x2b/0x40 blk_unregister_queue+0x53/0x180 __del_gendisk+0x226/0x690 del_gendisk+0xba/0x110 sd_remove+0x49/0xb0 [sd_mod] device_remove+0x87/0xb0 device_release_driver_internal+0x11e/0x230 device_release_driver+0x1a/0x30 bus_remove_device+0x14d/0x220 device_del+0x1e1/0x5a0 __scsi_remove_device+0x1ff/0x2f0 scsi_remove_device+0x37/0x60 sdev_store_delete+0x77/0x100 dev_attr_store+0x1f/0x40 sysfs_kf_write+0x65/0x90 kernfs_fop_write_iter+0x189/0x280 vfs_write+0x256/0x490 ksys_write+0x83/0x190 __x64_sys_write+0x21/0x30 x64_sys_call+0x4608/0x4630 do_syscall_64+0xdb/0x6b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e other info that might help us debug this: Chain exists of: &q->sysfs_lock --> &q->rq_qos_mutex --> &q->q_usage_counter(queue)#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(queue)#3); lock(&q->rq_qos_mutex); lock(&q->q_usage_counter(queue)#3); lock(&q->sysfs_lock); Root cause is that queue_usage_counter is grabbed with rq_qos_mutex held in blkg_conf_prep(), while queue should be freezed before rq_qos_mutex from other context. The blk_queue_enter() from blkg_conf_prep() is used to protect against policy deactivation, which is already protected with blkcg_mutex, hence convert blk_queue_enter() to blkcg_mutex to fix this problem. Meanwhile, consider that blkcg_mutex is held after queue is freezed from policy deactivation, also convert blkg_alloc() to use GFP_NOIO. Signed-off-by: Yu Kuai Reviewed-by: Ming Lei Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin