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INFO: task hung in worker_attach_to_pool (3)

Status: upstream: reported C repro on 2025/08/29 21:46
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+a50479d6d26ffd27e13b@syzkaller.appspotmail.com
First crash: 197d, last: 1d16h
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] INFO: task hung in worker_attach_to_pool (3) 0 (1) 2025/08/29 21:46
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in worker_attach_to_pool tipc 1 6 1936d 1941d 0/29 auto-closed as invalid on 2021/01/19 23:38
upstream INFO: task hung in worker_attach_to_pool (2) kernel 1 47 418d 517d 0/29 auto-obsoleted due to no activity on 2025/03/30 19:41
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/09/09 01:48 39m retest repro upstream report log
▶ ▼ Fix bisection attempts (4)
Created Duration User Patch Repo Result
2026/02/03 08:41 17m bisect fix upstream error job log
2025/12/16 18:52 3h21m bisect fix upstream OK (0) job log log
2025/11/15 12:38 3h09m bisect fix upstream OK (0) job log log
2025/10/11 10:03 4h00m bisect fix upstream OK (0) job log log

Sample crash report:
INFO: task kworker/R-rcu_g:4 blocked for more than 142 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-rcu_g state:D
 stack:29872 pid:4     tgid:4     ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task kworker/R-mm_pe:14 blocked for more than 142 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-mm_pe state:D stack:29872 pid:14    tgid:14    ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task kworker/R-mld:3177 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-mld   state:D stack:29472 pid:3177  tgid:3177  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task kworker/0:3:5962 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:3     state:D
 stack:25280 pid:5962  tgid:5962  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue:  0x0 (events)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 create_worker+0x537/0x7e0 kernel/workqueue.c:2833
 maybe_create_worker kernel/workqueue.c:3075 [inline]
 manage_workers kernel/workqueue.c:3152 [inline]
 worker_thread+0x4d5/0xfc0 kernel/workqueue.c:3414
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task kworker/R-wg-cr:6030 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-wg-cr state:D stack:29472 pid:6030  tgid:6030  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task kworker/R-wg-cr:6032 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-wg-cr state:D
 stack:29872 pid:6032  tgid:6032  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task kworker/R-wg-cr:6034 blocked for more than 146 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-wg-cr state:D stack:29872 pid:6034  tgid:6034  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task kworker/R-wg-cr:6280 blocked for more than 146 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-wg-cr state:D
 stack:29872 pid:6280  tgid:6280  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task kworker/R-wg-cr:6284 blocked for more than 147 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-wg-cr state:D stack:29872 pid:6284  tgid:6284  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task kworker/R-wg-cr:6285 blocked for more than 148 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-wg-cr state:D
 stack:29872 pid:6285  tgid:6285  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings
INFO: task kworker/R-wg-cr:6288 blocked for more than 149 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-wg-cr state:D stack:29872 pid:6288  tgid:6288  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings
INFO: task kworker/R-wg-cr:6289 blocked for more than 149 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-wg-cr state:D
 stack:29872 pid:6289  tgid:6289  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings
INFO: task kworker/R-wg-cr:6291 blocked for more than 150 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-wg-cr state:D stack:29872 pid:6291  tgid:6291  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings
INFO: task kworker/R-wg-cr:6292 blocked for more than 151 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/R-wg-cr state:D
 stack:29872 pid:6292  tgid:6292  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 worker_attach_to_pool+0x2e/0x3a0 kernel/workqueue.c:2691
 rescuer_thread+0x359/0x1120 kernel/workqueue.c:3575
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/10 00:08 upstream 1f318b96cc84 176bead5 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in worker_attach_to_pool
2025/08/25 21:37 upstream 1b237f190eb3 bf27483f .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in worker_attach_to_pool
2026/02/20 15:58 upstream 8bf22c33e7a1 741f5161 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in worker_attach_to_pool
2026/01/04 04:58 upstream aacb0a6d604a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in worker_attach_to_pool
* Struck through repros no longer work on HEAD.