syzbot


INFO: task hung in blkdev_get_by_dev (5)

Status: upstream: reported C repro on 2025/11/10 08:21
Reported-by: syzbot+0d446208a1f1e6c0e1fe@syzkaller.appspotmail.com
First crash: 4d06h, last: 2d12h
Similar bugs (12)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in blkdev_get_by_dev origin:lts-only 1 C done 25 368d 655d 3/3 fixed on 2025/01/02 10:34
linux-5.15 INFO: task hung in blkdev_get_by_dev (2) 1 1 796d 796d 0/3 auto-obsoleted due to no activity on 2023/12/18 22:46
upstream INFO: task hung in blkdev_get_by_dev (3) block 1 1 1346d 1346d 0/29 auto-closed as invalid on 2022/05/08 09:47
linux-5.15 INFO: task hung in blkdev_get_by_dev 1 1 927d 927d 0/3 auto-obsoleted due to no activity on 2023/08/23 09:06
linux-5.15 INFO: task hung in blkdev_get_by_dev (4) 1 3 171d 171d 0/3 auto-obsoleted due to no activity on 2025/09/04 06:30
linux-5.15 INFO: task hung in blkdev_get_by_dev (3) 1 17 431d 652d 0/3 auto-obsoleted due to no activity on 2024/12/17 17:06
linux-6.1 INFO: task hung in blkdev_get_by_dev (2) origin:upstream 1 C 9 10d 128d 0/3 upstream: reported C repro on 2025/07/08 23:59
upstream INFO: task hung in blkdev_get_by_dev fs 1 1 1725d 1725d 0/29 auto-closed as invalid on 2021/05/23 22:12
upstream INFO: task hung in blkdev_get_by_dev (4) block 1 1 1175d 1175d 0/29 auto-obsoleted due to no activity on 2022/11/25 11:03
linux-6.6 INFO: task hung in blkdev_get_by_dev origin:upstream 1 C 32 4d03h 146d 0/2 upstream: reported C repro on 2025/06/21 06:39
upstream INFO: task hung in blkdev_get_by_dev (2) block 1 1727 1377d 1457d 0/29 closed as dup on 2021/11/21 14:02
upstream INFO: task hung in blkdev_get_by_dev (5) block 1 C error error 32 216d 987d 0/29 upstream: reported C repro on 2023/03/02 18:11

Sample crash report:
INFO: task udevd:3561 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:26120 pid: 3561 ppid:     1 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xc71/0x2390 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 blkdev_get_by_dev+0x157/0xa60 block/bdev.c:820
 blkdev_open+0x12d/0x2c0 block/fops.c:466
 do_dentry_open+0x7ff/0xf80 fs/open.c:826
 do_open fs/namei.c:3616 [inline]
 path_openat+0x2682/0x2f30 fs/namei.c:3750
 do_filp_open+0x1b3/0x3e0 fs/namei.c:3777
 do_sys_openat2+0x142/0x4a0 fs/open.c:1253
 do_sys_open fs/open.c:1269 [inline]
 __do_sys_openat fs/open.c:1285 [inline]
 __se_sys_openat fs/open.c:1280 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1280
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fd55ac63407
RSP: 002b:00007ffc5e5de390 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fd55ab75880 RCX: 00007fd55ac63407
RDX: 00000000000a0800 RSI: 0000558ab7589ee0 RDI: ffffffffffffff9c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000558aab7a1100 R14: 0000000000000000 R15: 00007ffc5e5de620
 </TASK>
INFO: task udevd:4258 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:25312 pid: 4258 ppid:  3561 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 io_schedule+0x7c/0xd0 kernel/sched/core.c:8503
 wait_on_page_bit_common+0x815/0xe00 mm/filemap.c:1356
 wait_on_page_bit mm/filemap.c:1417 [inline]
 wait_on_page_locked include/linux/pagemap.h:688 [inline]
 wait_on_page_read mm/filemap.c:3437 [inline]
 do_read_cache_page+0xb05/0x1030 mm/filemap.c:3480
 read_mapping_page include/linux/pagemap.h:515 [inline]
 read_part_sector+0xd4/0x4f0 block/partitions/core.c:731
 adfspart_check_ICS+0xbf/0xe00 block/partitions/acorn.c:360
 check_partition block/partitions/core.c:148 [inline]
 blk_add_partitions block/partitions/core.c:616 [inline]
 bdev_disk_changed+0x917/0x16b0 block/partitions/core.c:702
 blkdev_get_whole+0x2f9/0x390 block/bdev.c:682
 blkdev_get_by_dev+0x2d0/0xa60 block/bdev.c:827
 blkdev_open+0x12d/0x2c0 block/fops.c:466
 do_dentry_open+0x7ff/0xf80 fs/open.c:826
 do_open fs/namei.c:3616 [inline]
 path_openat+0x2682/0x2f30 fs/namei.c:3750
 do_filp_open+0x1b3/0x3e0 fs/namei.c:3777
 do_sys_openat2+0x142/0x4a0 fs/open.c:1253
 do_sys_open fs/open.c:1269 [inline]
 __do_sys_openat fs/open.c:1285 [inline]
 __se_sys_openat fs/open.c:1280 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1280
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fd55ac63407
RSP: 002b:00007ffc5e5de1d0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fd55ab75880 RCX: 00007fd55ac63407
RDX: 00000000000a0800 RSI: 0000558ab75971b0 RDI: ffffffffffffff9c
RBP: 0000558ab757c910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000558ab759faf0
R13: 0000558ab7594410 R14: 0000000000000000 R15: 0000558ab759faf0
 </TASK>
INFO: task syz.0.17:4529 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:27136 pid: 4529 ppid:  4389 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xc71/0x2390 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 blkdev_put+0xf9/0x7d0 block/bdev.c:915
 blkdev_close+0x76/0xa0 block/fops.c:478
 __fput+0x234/0x930 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f70619d36c9
RSP: 002b:00007f7061042038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 00007f7061c29fa0 RCX: 00007f70619d36c9
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 00007f7061a55f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7061c2a038 R14: 00007f7061c29fa0 R15: 00007ffeaf0d9dc8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/u4:4/3062:
 #0: ffff8880b913a358 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
 #1: ffff8880b9127888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x4d6/0x810 kernel/sched/psi.c:891
1 lock held by udevd/3561:
 #0: ffff888020ba0518 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x157/0xa60 block/bdev.c:820
2 locks held by getty/3953:
 #0: ffff88802c484098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900025e62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
1 lock held by udevd/4258:
 #0: ffff888020ba0518 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x157/0xa60 block/bdev.c:820
1 lock held by syz.0.17/4529:
 #0: ffff888020ba0518 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xf9/0x7d0 block/bdev.c:915

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4245 Comm: kworker/u4:5 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: phy7 ieee80211_iface_work
RIP: 0010:look_up_lock_class+0x81/0x110 kernel/locking/lockdep.c:895
Code: 80 46 86 c8 61 49 0f af c7 48 c1 e8 34 48 8b 1c c5 00 27 85 92 e8 4f 01 00 00 48 85 db 74 4b 4c 39 7b 40 74 05 48 8b 1b eb eb <48> 8b 83 b0 00 00 00 49 3b 46 18 74 35 49 81 3e 80 df b2 8f 74 2c
RSP: 0018:ffffc9000305f790 EFLAGS: 00000046
RAX: 0000000000000001 RBX: ffffffff8f9acdc0 RCX: ffff88801fafbb80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc9000305fd00
RBP: ffffc9000305f890 R08: dffffc0000000000 R09: 0000000000000000
R10: fffffbfff1ad33a6 R11: 1ffffffff1ad33a5 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffc9000305fd00 R15: ffffffff964c58c0
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb8082a8f98 CR3: 000000005cf60000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 register_lock_class+0xb1/0x880 kernel/locking/lockdep.c:1245
 __lock_acquire+0x160/0x7c60 kernel/locking/lockdep.c:4891
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 process_one_work+0x7bf/0x1000 kernel/workqueue.c:2286
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/12 02:10 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
2025/11/11 22:26 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
2025/11/11 18:54 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
2025/11/11 15:07 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
2025/11/11 11:15 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
2025/11/11 07:11 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
2025/11/11 03:23 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
2025/11/10 19:24 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
2025/11/10 15:40 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
2025/11/10 11:59 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
2025/11/10 08:20 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in blkdev_get_by_dev
* Struck through repros no longer work on HEAD.