syzbot


INFO: task hung in rfkill_sync_work

Status: upstream: reported on 2025/11/25 13:57
Reported-by: syzbot+f35044e04a4bb7b7b9cd@syzkaller.appspotmail.com
First crash: 26d, last: 26d
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in rfkill_sync_work 1 1 860d 860d 0/3 auto-obsoleted due to no activity on 2023/11/22 22:14
linux-6.1 INFO: task hung in rfkill_sync_work (3) origin:upstream 1 syz error 2 259d 273d 0/3 upstream: reported syz repro on 2025/03/23 22:31
linux-5.15 INFO: task hung in rfkill_sync_work 1 1 841d 841d 0/3 auto-obsoleted due to no activity on 2023/12/11 11:27
upstream INFO: task hung in rfkill_sync_work net nfc 1 C done 108 3h18m 1091d 0/29 upstream: reported C repro on 2022/12/26 19:45
linux-6.1 INFO: task hung in rfkill_sync_work (2) 1 1 406d 406d 0/3 auto-obsoleted due to no activity on 2025/02/18 16:28

Sample crash report:
INFO: task kworker/1:2:786 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:2     state:D stack:24688 pid:786   ppid:2      flags:0x00004000
Workqueue: events rfkill_sync_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
 rfkill_sync_work+0x2e/0x200 net/rfkill/core.c:1059
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
INFO: task kworker/1:6:5861 blocked for more than 146 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:6     state:D stack:24616 pid:5861  ppid:2      flags:0x00004000
Workqueue: events rfkill_global_led_trigger_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
 rfkill_global_led_trigger_worker+0x27/0xd0 net/rfkill/core.c:182
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
INFO: task syz.6.893:11034 blocked for more than 146 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.893       state:D stack:27016 pid:11034 ppid:10098  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x9b/0x280 kernel/time/timer.c:2143
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x2bd/0x590 kernel/sched/completion.c:148
 __flush_work+0x895/0x9f0 kernel/workqueue.c:3430
 __cancel_work_timer+0x3b0/0x520 kernel/workqueue.c:3517
 rfkill_unregister+0x92/0x220 net/rfkill/core.c:1143
 nfc_unregister_device+0x96/0x2a0 net/nfc/core.c:1167
 virtual_ncidev_close+0x59/0x90 drivers/nfc/virtual_ncidev.c:172
 __fput+0x234/0x970 fs/file_table.c:384
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f2881d8f749
RSP: 002b:00007ffc4cda6378 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f2881fe7da0 RCX: 00007f2881d8f749
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f2881fe7da0 R08: 0000000000000200 R09: 0000001c4cda666f
R10: 00000000003ffbdc R11: 0000000000000246 R12: 0000000000079c82
R13: 00007f2881fe6090 R14: ffffffffffffffff R15: 00007ffc4cda6490
 </TASK>
INFO: task syz.4.894:11048 blocked for more than 147 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.894       state:D stack:24176 pid:11048 ppid:10029  flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
 device_lock include/linux/device.h:995 [inline]
 nfc_dev_down net/nfc/core.c:143 [inline]
 nfc_rfkill_set_block+0x50/0x2e0 net/nfc/core.c:179
 rfkill_set_block+0x1c6/0x420 net/rfkill/core.c:346
 rfkill_fop_write+0x45c/0x570 net/rfkill/core.c:1305
 vfs_write+0x288/0x940 fs/read_write.c:582
 ksys_write+0x147/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3fae98f749
RSP: 002b:00007f3faf792038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f3faebe6180 RCX: 00007f3fae98f749
RDX: 0000000000000008 RSI: 0000200000000080 RDI: 0000000000000003
RBP: 00007f3faea13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3faebe6218 R14: 00007f3faebe6180 R15: 00007ffec96fb628
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
3 locks held by kworker/1:2/786:
 #0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90003b77d00 ((work_completion)(&rfkill->sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90003b77d00 ((work_completion)(&rfkill->sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_sync_work+0x2e/0x200 net/rfkill/core.c:1059
2 locks held by getty/5548:
 #0: ffff88802ca6d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
3 locks held by kworker/1:6/5861:
 #0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000493fd00 ((work_completion)(&rfkill_global_led_trigger_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000493fd00 ((work_completion)(&rfkill_global_led_trigger_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_global_led_trigger_worker+0x27/0xd0 net/rfkill/core.c:182
1 lock held by syz.0.293/8216:
 #0: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_unregister+0xc8/0x220 net/rfkill/core.c:1149
1 lock held by syz-executor/9938:
 #0: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_unregister+0xc8/0x220 net/rfkill/core.c:1149
1 lock held by syz.6.893/11034:
 #0: ffff888069a4d100 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:995 [inline]
 #0: ffff888069a4d100 (&dev->mutex){....}-{3:3}, at: nfc_unregister_device+0x63/0x2a0 net/nfc/core.c:1165
2 locks held by syz.4.894/11048:
 #0: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_fop_write+0x1a2/0x570 net/rfkill/core.c:1297
 #1: ffff888069a4d100 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:995 [inline]
 #1: ffff888069a4d100 (&dev->mutex){....}-{3:3}, at: nfc_dev_down net/nfc/core.c:143 [inline]
 #1: ffff888069a4d100 (&dev->mutex){....}-{3:3}, at: nfc_rfkill_set_block+0x50/0x2e0 net/nfc/core.c:179
2 locks held by syz-executor/11387:
 #0: ffff888060c94918 (&data->open_mutex){+.+.}-{3:3}, at: vhci_create_device+0x34/0x650 drivers/bluetooth/hci_vhci.c:479
 #1: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_register+0x37/0x8e0 net/rfkill/core.c:1075
2 locks held by syz-executor/11389:
 #0: ffff888060c94118 (&data->open_mutex){+.+.}-{3:3}, at: vhci_create_device+0x34/0x650 drivers/bluetooth/hci_vhci.c:479
 #1: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_register+0x37/0x8e0 net/rfkill/core.c:1075
2 locks held by syz-executor/12367:
 #0: ffff8880582a1118 (&data->open_mutex){+.+.}-{3:3}, at: vhci_create_device+0x34/0x650 drivers/bluetooth/hci_vhci.c:479
 #1: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_register+0x37/0x8e0 net/rfkill/core.c:1075
2 locks held by syz-executor/12374:
 #0: ffff888031465118 (&data->open_mutex){+.+.}-{3:3}, at: vhci_create_device+0x34/0x650 drivers/bluetooth/hci_vhci.c:479
 #1: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_register+0x37/0x8e0 net/rfkill/core.c:1075
2 locks held by syz-executor/13266:
 #0: ffff88807c2bb118 (&data->open_mutex){+.+.}-{3:3}, at: vhci_create_device+0x34/0x650 drivers/bluetooth/hci_vhci.c:479
 #1: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_register+0x37/0x8e0 net/rfkill/core.c:1075
2 locks held by syz-executor/13272:
 #0: ffff888059bf9118 (&data->open_mutex){+.+.}-{3:3}, at: vhci_create_device+0x34/0x650 drivers/bluetooth/hci_vhci.c:479
 #1: ffffffff8e2979a8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_register+0x37/0x8e0 net/rfkill/core.c:1075
1 lock held by dhcpcd-run-hook/13589:

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 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+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf41/0xf80 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5139 Comm: syslogd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:rcu_read_lock_sched_held+0x40/0x100 kernel/rcu/update.c:120
Code: 48 8b 04 25 28 00 00 00 48 89 44 24 50 48 c7 04 24 b3 8a b5 41 48 c7 44 24 08 ae 1f 78 8c 48 c7 44 24 10 80 80 6e 81 49 89 e6 <49> c1 ee 03 48 b8 f1 f1 f1 f1 00 f3 f3 f3 49 bf 00 00 00 00 00 fc
RSP: 0018:ffffc90003247660 EFLAGS: 00000086
RAX: c0a254db5446c400 RBX: ffffffff8cbf7400 RCX: ffff88807ea6bc00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88807e67da00
RBP: ffffc900032476e0 R08: dffffc0000000000 R09: 1ffffffff21b52a2
R10: dffffc0000000000 R11: fffffbfff21b52a3 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffc90003247660 R15: ffff88807e67da00
FS:  00007f48de09ec80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564b574d2d51 CR3: 000000002f8cb000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 task_css_set include/linux/cgroup.h:423 [inline]
 task_dfl_cgroup include/linux/cgroup.h:492 [inline]
 task_psi_group+0x50/0x1a0 kernel/sched/psi.c:896
 psi_task_change+0x1b7/0x4e0 kernel/sched/psi.c:928
 psi_enqueue kernel/sched/stats.h:143 [inline]
 enqueue_task+0x275/0x2c0 kernel/sched/core.c:2097
 activate_task kernel/sched/core.c:2131 [inline]
 ttwu_do_activate+0x1d6/0x7d0 kernel/sched/core.c:3785
 ttwu_queue kernel/sched/core.c:4027 [inline]
 try_to_wake_up+0x686/0x1140 kernel/sched/core.c:4348
 autoremove_wake_function+0x17/0x100 kernel/sched/wait.c:424
 __wake_up_common+0x2a4/0x4e0 kernel/sched/wait.c:107
 __wake_up_common_lock kernel/sched/wait.c:138 [inline]
 __wake_up_sync_key+0x111/0x190 kernel/sched/wait.c:213
 __unix_dgram_recvmsg+0x49c/0xd60 net/unix/af_unix.c:2437
 sock_recvmsg_nosec net/socket.c:1046 [inline]
 sock_recvmsg net/socket.c:1068 [inline]
 sock_read_iter+0x2b7/0x3b0 net/socket.c:1138
 call_read_iter include/linux/fs.h:2012 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x431/0x920 fs/read_write.c:470
 ksys_read+0x147/0x250 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f48de1ee407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffc67f87290 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f48de09ec80 RCX: 00007f48de1ee407
RDX: 00000000000000ff RSI: 000055d963bc4950 RDI: 0000000000000000
RBP: 000055d963bc4910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055d963bc498d
R13: 0000000000000000 R14: 000055d963bc4950 R15: 000055d93c3e6d98
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/25 13:57 linux-6.6.y 1e89a1be4fe9 64219f15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in rfkill_sync_work
* Struck through repros no longer work on HEAD.