syzbot


INFO: task hung in worker_thread (6)

Status: upstream: reported C repro on 2026/02/02 18:05
Subsystems: hfs
[Documentation on labels]
Reported-by: syzbot+fa1cc3e4b001b79309ec@syzkaller.appspotmail.com
First crash: 103d, last: 45d
Cause bisection: failed (error log, bisect log)
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [hfs?] INFO: task hung in worker_thread (6) 0 (1) 2026/02/02 18:05
Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in worker_thread 1 1 1586d 1586d 0/1 auto-closed as invalid on 2022/05/08 06:12
upstream INFO: task hung in worker_thread (3) serial 1 1 1179d 1179d 0/29 auto-obsoleted due to no activity on 2023/05/20 16:01
upstream INFO: task hung in worker_thread (5) kernel 1 C done done 49 243d 590d 0/29 auto-obsoleted due to no activity on 2025/12/21 10:04
upstream INFO: task hung in worker_thread (4) kernel 1 1 863d 863d 0/29 auto-obsoleted due to no activity on 2024/03/31 02:07
android-6-12 INFO: task hung in worker_thread 1 2 305d 313d 0/1 auto-obsoleted due to no activity on 2025/10/10 04:19
upstream INFO: task hung in worker_thread (2) fs 1 1 1939d 1939d 0/29 auto-closed as invalid on 2021/05/17 11:26
linux-5.15 INFO: task hung in worker_thread 1 1 555d 555d 0/3 auto-obsoleted due to no activity on 2025/02/12 21:25
android-6-12 INFO: task hung in worker_thread (2) 1 1 200d 200d 0/1 auto-obsoleted due to no activity on 2026/01/23 01:25
upstream INFO: task hung in worker_thread fs 1 1 2104d 2104d 0/29 auto-closed as invalid on 2020/11/06 03:23
Last patch testing requests (3)
Created Duration User Patch Repo Result
2026/04/24 22:06 38m retest repro linux-next OK log
2026/04/24 21:44 41m retest repro linux-next OK log
2026/02/13 13:17 50m retest repro linux-next report log

Sample crash report:
INFO: task kworker/u8:1:13 blocked for more than 144 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:1    state:I stack:23528 pid:13    tgid:13    ppid:2      task_flags:0x4208160 flags:0x00080000
Workqueue:  0x0 (wg-kex-wg1)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0xfee/0x60e0 kernel/sched/core.c:6907
 __schedule_loop kernel/sched/core.c:6989 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7004
 worker_thread+0x526/0xe40 kernel/workqueue.c:3454
 kthread+0x370/0x450 kernel/kthread.c:467
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Showing all locks held in the system:
2 locks held by kthreadd/2:
3 locks held by kworker/u8:0/12:
1 lock held by khungtaskd/30:
 #0: ffffffff8e7e93e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8e7e93e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8e7e93e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
4 locks held by kworker/u8:2/35:
2 locks held by kswapd0/77:
3 locks held by kworker/u8:8/1121:
3 locks held by kworker/u8:9/1146:
4 locks held by kworker/u8:10/1157:
3 locks held by kworker/u8:12/3043:
1 lock held by klogd/5169:
2 locks held by udevd/5180:
1 lock held by dhcpcd/5474:
5 locks held by dhcpcd/5475:
2 locks held by getty/5572:
 #0: ffff8880394b90a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211
1 lock held by syz-executor/5792:
2 locks held by syz-executor/5814:
2 locks held by syz-executor/5816:
5 locks held by kworker/1:4/5870:
3 locks held by kworker/1:6/5925:
 #0: ffff88813fe63548 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1287/0x1920 kernel/workqueue.c:3250
 #1: ffffc90004c57d08 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x93c/0x1920 kernel/workqueue.c:3251
 #2: ffffffff8e7f4ff8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
2 locks held by udevd/6313:
2 locks held by udevd/6493:
1 lock held by syz.2.620/7957:
 #0: ffffffff8e7f4ff8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
2 locks held by vhost-7958/7960:
2 locks held by syz-executor/8003:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x141/0x190 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xd25/0x1050 kernel/hung_task.c:515
 kthread+0x370/0x450 kernel/kthread.c:467
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G             L      syzkaller #0 PREEMPT(full) 

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/22 03:05 upstream d79526b89571 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in worker_thread
2026/03/29 10:29 net dc9e9d61e301 356bdfc9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in worker_thread
2026/03/25 17:02 net-next d1e59a469737 4367a094 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in worker_thread
2026/03/14 14:45 net-next 9089c5f3c444 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in worker_thread
2026/01/30 11:43 linux-next 33a647c659ff bfa73b7b .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root INFO: task hung in worker_thread
* Struck through repros no longer work on HEAD.