INFO: task hung in blk_mq_get_tag

Status: upstream: reported C repro on 2026/08/20 16:56
Reported-by: syzbot+54bb838fea8f9a7949d9@syzkaller.appspotmail.com
First crash: 8d19h, last: 7d17h
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-414 INFO: task hung in blk_mq_get_tag 1 1 2839d 2694d 0/1 auto-closed as invalid on 2019/05/19 02:21
upstream INFO: task hung in blk_mq_get_tag block 1 1 697d 697d 0/29 auto-obsoleted due to no activity on 2024/12/30 04:00

Sample crash report:
INFO: task syz.0.47:4474 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.47        state:D stack:0     pid:4474  ppid:4427   flags:0x00000001
Call trace:
 __switch_to+0x2f4/0x550 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0xdb4/0x1a6c kernel/sched/core.c:6563
 schedule+0xc4/0x170 kernel/sched/core.c:6639
 io_schedule+0x84/0x154 kernel/sched/core.c:8799
 blk_mq_get_tag+0x46c/0x9d8 block/blk-mq-tag.c:190
 __blk_mq_alloc_requests+0x7c4/0xb00 block/blk-mq.c:500
 blk_mq_alloc_request+0x1dc/0x590 block/blk-mq.c:595
 nvme_alloc_user_request drivers/nvme/host/ioctl.c:83 [inline]
 nvme_submit_user_cmd+0x128/0x400 drivers/nvme/host/ioctl.c:164
 nvme_user_cmd64+0x34c/0x560 drivers/nvme/host/ioctl.c:353
 nvme_dev_ioctl+0xb0/0x3a0 drivers/nvme/host/ioctl.c:909
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Showing all locks held in the system:
2 locks held by kworker/u4:0/9:
1 lock held by rcu_tasks_kthre/12:
 #0: ffff800015577db0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xc48 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffff8000155785d0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xc48 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffff800015577440 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:349
2 locks held by getty/4084:
 #0: ffff0000d6d4d098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff80001fa232f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x2e8/0xfa8 drivers/tty/n_tty.c:2198
3 locks held by kworker/1:10/4438:
 #0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x69c/0x13bc kernel/workqueue.c:-1
 #1: ffff8000212a7c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x6e8/0x13bc kernel/workqueue.c:2267
 #2: ffff0000cde73240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x1d8/0x2708 drivers/net/netdevsim/fib.c:1491

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Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/21 19:27 linux-6.1.y 7e6e67054721 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in blk_mq_get_tag
2026/08/21 16:40 linux-6.1.y 7e6e67054721 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in blk_mq_get_tag
2026/08/21 13:33 linux-6.1.y 7e6e67054721 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in blk_mq_get_tag
2026/08/21 10:23 linux-6.1.y 7e6e67054721 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in blk_mq_get_tag
2026/08/21 07:13 linux-6.1.y 7e6e67054721 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in blk_mq_get_tag
2026/08/21 04:09 linux-6.1.y 7e6e67054721 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in blk_mq_get_tag
2026/08/21 01:15 linux-6.1.y 7e6e67054721 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in blk_mq_get_tag
2026/08/20 22:30 linux-6.1.y 7e6e67054721 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in blk_mq_get_tag
2026/08/20 19:43 linux-6.1.y 7e6e67054721 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in blk_mq_get_tag
2026/08/20 16:55 linux-6.1.y 7e6e67054721 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in blk_mq_get_tag
* Struck through repros no longer work on HEAD.