syzbot


INFO: task hung in netdev_run_todo (4)

Status: upstream: reported on 2024/10/09 19:06
Subsystems: wireguard
[Documentation on labels]
Reported-by: syzbot+894cca71fa925aabfdb2@syzkaller.appspotmail.com
First crash: 573d, last: 18h22m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
a523f87b-dddb-4709-b009-c24d923b52ca repro INFO: task hung in netdev_run_todo (4) 2026/03/07 09:34 2026/03/07 09:34 2026/03/07 09:43 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
Discussions (5)
Title Replies (including bot) Last reply
[syzbot] Monthly wireguard report (Nov 2025) 0 (1) 2025/11/30 10:08
[syzbot] Monthly wireguard report (May 2025) 0 (1) 2025/05/12 06:34
[syzbot] Monthly wireguard report (Feb 2025) 0 (1) 2025/02/26 15:11
[syzbot] Monthly wireguard report (Dec 2024) 0 (1) 2024/12/26 09:01
[syzbot] [net?] INFO: task hung in netdev_run_todo (4) 0 (1) 2024/10/09 19:06
Similar bugs (17)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in netdev_run_todo (3) 1 15 1225d 1541d 0/1 auto-obsoleted due to no activity on 2023/03/07 08:19
linux-6.6 INFO: task hung in netdev_run_todo 1 1 192d 192d 0/2 auto-obsoleted due to no activity on 2025/12/14 15:00
linux-5.15 INFO: task hung in netdev_run_todo (3) 1 1 80d 80d 0/3 upstream: reported on 2025/12/26 15:48
upstream INFO: task hung in netdev_run_todo net 1 12 2399d 2954d 0/29 closed as invalid on 2019/10/23 07:29
linux-4.19 INFO: task hung in netdev_run_todo (2) 1 3 2032d 2080d 0/1 auto-closed as invalid on 2020/12/20 04:57
android-44 INFO: task hung in netdev_run_todo 1 1 2893d 2893d 0/2 auto-closed as invalid on 2019/02/22 12:49
android-6-12 INFO: task hung in netdev_run_todo (2) 1 43 5d18h 53d 0/1 premoderation: reported on 2026/01/22 03:02
linux-4.19 INFO: task hung in netdev_run_todo 1 1 2358d 2358d 0/1 auto-closed as invalid on 2020/01/29 06:48
upstream INFO: task hung in netdev_run_todo (3) net 1 24 636d 674d 0/29 auto-obsoleted due to no activity on 2024/08/07 04:24
linux-5.15 INFO: task hung in netdev_run_todo 1 1 871d 871d 0/3 auto-obsoleted due to no activity on 2024/02/04 09:09
linux-6.6 INFO: task hung in netdev_run_todo (2) 1 1 60d 60d 0/2 upstream: reported on 2026/01/14 20:32
upstream INFO: task hung in netdev_run_todo (2) staging wireguard usb 1 C error 241 762d 1918d 0/29 auto-obsoleted due to no activity on 2024/05/05 22:51
android-49 INFO: task hung in netdev_run_todo 1 1 2886d 2885d 0/3 auto-closed as invalid on 2019/02/22 14:57
linux-4.14 INFO: task hung in netdev_run_todo 1 1 1218d 1218d 0/1 auto-obsoleted due to no activity on 2023/03/13 17:45
android-6-12 INFO: task hung in netdev_run_todo 1 184 122d 267d 0/1 auto-obsoleted due to no activity on 2026/01/03 01:56
linux-5.15 INFO: task hung in netdev_run_todo (2) 1 54 483d 664d 0/3 auto-obsoleted due to no activity on 2025/01/26 20:30
upstream INFO: task can't die in netdev_run_todo net 1 syz error 2 1641d 2034d 0/29 auto-obsoleted due to no activity on 2023/04/16 04:59

Sample crash report:
INFO: task kworker/u8:18:6390 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:18   state:D stack:20224 pid:6390  tgid:6390  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7286
 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1647
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
 rt_mutex_slowlock+0x2dc/0x7b0 kernel/locking/rtmutex.c:1800
 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:552
 rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
 netdev_run_todo+0x2e0/0xde0 net/core/dev.c:11695
 nsim_destroy+0x3ae/0x680 drivers/net/netdevsim/netdev.c:1189
 __nsim_dev_port_del+0x14d/0x1b0 drivers/net/netdevsim/dev.c:1528
 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1540 [inline]
 nsim_dev_reload_destroy+0x288/0x490 drivers/net/netdevsim/dev.c:1764
 nsim_dev_reload_down+0x8a/0xc0 drivers/net/netdevsim/dev.c:1038
 devlink_reload+0x1d1/0x8e0 net/devlink/dev.c:461
 devlink_pernet_pre_exit+0x1e6/0x3f0 net/devlink/core.c:507
 ops_pre_exit_list net/core/net_namespace.c:161 [inline]
 ops_undo_list+0x187/0x940 net/core/net_namespace.c:234
 cleanup_net+0x56e/0x800 net/core/net_namespace.c:704
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 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 syz-executor:6518 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:19424 pid:6518  tgid:6518  ppid:1      task_flags:0x40054c flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7286
 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1647
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
 rt_mutex_slowlock+0x2dc/0x7b0 kernel/locking/rtmutex.c:1800
 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:552
 rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
 netdev_run_todo+0x2e0/0xde0 net/core/dev.c:11695
 tun_detach drivers/net/tun.c:640 [inline]
 tun_chr_close+0x13f/0x1c0 drivers/net/tun.c:3436
 __fput+0x461/0xa90 fs/file_table.c:469
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x70f/0x23c0 kernel/exit.c:976
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1118
 get_signal+0x125c/0x1310 kernel/signal.c:3034
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7bb56ccfce
RSP: 002b:00007ffd740d5d68 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: 0000000000000084 RBX: 0000555557912500 RCX: 00007f7bb56ccfce
RDX: 0000000000000084 RSI: 00007f7bb64b4670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffd740d5de4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f7bb64b4670 R15: 0000000000000000
 </TASK>
INFO: task syz-executor:6522 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:18560 pid:6522  tgid:6522  ppid:1      task_flags:0x40054c flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7286
 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1647
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
 rt_mutex_slowlock+0x2dc/0x7b0 kernel/locking/rtmutex.c:1800
 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:552
 rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
 netdev_run_todo+0x2e0/0xde0 net/core/dev.c:11695
 tun_detach drivers/net/tun.c:640 [inline]
 tun_chr_close+0x13f/0x1c0 drivers/net/tun.c:3436
 __fput+0x461/0xa90 fs/file_table.c:469
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x70f/0x23c0 kernel/exit.c:976
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1118
 get_signal+0x125c/0x1310 kernel/signal.c:3034
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f680cd4cfce
RSP: 002b:00007ffedd94e4d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: 0000000000000084 RBX: 00005555919e8500 RCX: 00007f680cd4cfce
RDX: 0000000000000084 RSI: 00007f680db34670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffedd94e554 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f680db34670 R15: 0000000000000000
 </TASK>

Showing all locks held in the system:
4 locks held by rcuc/0/20:
4 locks held by rcuc/1/28:
2 locks held by ksoftirqd/1/30:
1 lock held by khungtaskd/37:
 #0: ffffffff8ddcb8c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8ddcb8c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8ddcb8c0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
7 locks held by kworker/u8:4/68:
3 locks held by kworker/u8:6/141:
 #0: ffff888031e6c138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #0: ffff888031e6c138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
 #1: ffffc90003a4fc40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
 #1: ffffc90003a4fc40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
 #2: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x19/0x30 net/ipv6/addrconf.c:4738
2 locks held by getty/5552:
 #0: ffff8880287e90a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e832e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
7 locks held by kworker/u8:13/5955:
3 locks held by kworker/0:7/5979:
6 locks held by kworker/u8:18/6390:
 #0: ffff88801aee1138 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #0: ffff88801aee1138 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
 #1: ffffc90005e17c40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
 #1: ffffc90005e17c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
 #2: ffffffff8f14c0c0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf4/0x800 net/core/net_namespace.c:675
 #3: ffff88805eca70d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #3: ffff88805eca70d8 (&dev->mutex){....}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:108 [inline]
 #3: ffff88805eca70d8 (&dev->mutex){....}-{4:4}, at: devlink_pernet_pre_exit+0x117/0x3f0 net/devlink/core.c:504
 #4: ffff888020736300 (&devlink->lock_key){+.+.}-{4:4}, at: devl_lock net/devlink/core.c:274 [inline]
 #4: ffff888020736300 (&devlink->lock_key){+.+.}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:109 [inline]
 #4: ffff888020736300 (&devlink->lock_key){+.+.}-{4:4}, at: devlink_pernet_pre_exit+0x129/0x3f0 net/devlink/core.c:504
 #5: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz.3.145/6435:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz.0.168/6513:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6518:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6522:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6547:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6549:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6557:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6584:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6591:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6605:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6606:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6614:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/6656:
 #0: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
2 locks held by syz-executor/6661:
 #0: ffffffff8f14c0c0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:577
 #1: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
2 locks held by syz-executor/6668:
 #0: ffffffff8f14c0c0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:577
 #1: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
2 locks held by syz-executor/6669:
 #0: ffffffff8f14c0c0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:577
 #1: ffffffff8ddd1b30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
4 locks held by syz-executor/6676:
2 locks held by syz-executor/6690:
 #0: ffffffff8f14c0c0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:577
 #1: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: register_nexthop_notifier+0x88/0x290 net/ipv4/nexthop.c:3976
2 locks held by syz-executor/6691:
 #0: ffffffff8f14c0c0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:577
 #1: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock_killable include/linux/rtnetlink.h:145 [inline]
 #1: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: register_netdev+0x18/0x60 net/core/dev.c:11537
1 lock held by syz-executor/6700:
 #0: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x404/0x1ad0 net/ipv4/devinet.c:978
1 lock held by syz-executor/6702:
 #0: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x404/0x1ad0 net/ipv4/devinet.c:978
1 lock held by syz-executor/6703:
 #0: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8f15a878 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x404/0x1ad0 net/ipv4/devinet.c:978

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 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+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xfd9/0x1030 kernel/hung_task.c:515
 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>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 20 Comm: rcuc/0 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline]
RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline]
RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
RIP: 0010:rcu_is_watching+0x5e/0xb0 kernel/rcu/tree.c:752
Code: 03 42 80 3c 38 00 74 08 4c 89 f7 e8 6c 0e 81 00 48 c7 c3 18 7f 4f 92 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 84 c0 75 34 <8b> 03 65 ff 0d c9 d7 a4 10 74 11 83 e0 04 c1 e8 02 5b 41 5e 41 5f
RSP: 0018:ffffc90000196890 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff8880b8833f18 RCX: 0000000080000001
RDX: 0000000000000100 RSI: ffffffff8ba665e0 RDI: ffffffff8ba665a0
RBP: ffffc90000196a30 R08: 0000000000000000 R09: 0000000000000100
R10: ffffc90000196820 R11: fffff52000032d06 R12: dffffc0000000000
R13: ffffc90000196ab0 R14: ffffffff8d802790 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88812633c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f899df2a435 CR3: 000000000dbba000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 rcu_read_lock_held_common kernel/rcu/update.c:109 [inline]
 rcu_read_lock_held+0x15/0x50 kernel/rcu/update.c:349
 rt6_select net/ipv6/route.c:916 [inline]
 fib6_table_lookup+0x245/0xa80 net/ipv6/route.c:2247
 ip6_pol_route+0x228/0x13d0 net/ipv6/route.c:2283
 pol_lookup_func include/net/ip6_fib.h:617 [inline]
 fib6_rule_lookup+0x222/0x730 net/ipv6/fib6_rules.c:120
 ip6_route_output_flags_noref net/ipv6/route.c:2698 [inline]
 ip6_route_output_flags+0x364/0x5d0 net/ipv6/route.c:2710
 ip6_route_output include/net/ip6_route.h:93 [inline]
 __nf_ip6_route+0x42/0xd0 net/ipv6/netfilter.c:116
 nf_ip6_route include/linux/netfilter_ipv6.h:111 [inline]
 synproxy_send_tcp_ipv6+0x275/0x6d0 net/netfilter/nf_synproxy_core.c:836
 synproxy_send_client_synack_ipv6+0x814/0xcb0 net/netfilter/nf_synproxy_core.c:898
 nft_synproxy_eval_v6+0x34a/0x4e0 net/netfilter/nft_synproxy.c:91
 nft_synproxy_do_eval+0x3ce/0x580 net/netfilter/nft_synproxy.c:146
 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
 nft_do_chain+0x45e/0x1990 net/netfilter/nf_tables_core.c:285
 nft_do_chain_inet+0x29d/0x380 net/netfilter/nft_chain_filter.c:161
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xc5/0x220 net/netfilter/core.c:623
 nf_hook include/linux/netfilter.h:273 [inline]
 NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:316
 ip6_input+0x16a/0x270 net/ipv6/ip6_input.c:500
 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318
 __netif_receive_skb_one_core net/core/dev.c:6164 [inline]
 __netif_receive_skb net/core/dev.c:6277 [inline]
 process_backlog+0x3ce/0xc60 net/core/dev.c:6628
 __napi_poll+0xaf/0x580 net/core/dev.c:7692
 napi_poll net/core/dev.c:7755 [inline]
 net_rx_action+0x696/0xe00 net/core/dev.c:7912
 handle_softirqs+0x1de/0x6f0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 __local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_do_batch kernel/rcu/tree.c:2636 [inline]
 rcu_core kernel/rcu/tree.c:2869 [inline]
 rcu_cpu_kthread+0x9e8/0x1470 kernel/rcu/tree.c:2957
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 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>

Crashes (782):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/15 21:28 upstream 267594792a71 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/15 17:27 upstream 267594792a71 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/15 13:56 upstream 267594792a71 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/15 11:44 upstream 267594792a71 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/15 05:28 upstream 69237f8c1f69 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/13 18:34 upstream b36eb6e3f5d8 351cb5cf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/13 14:38 upstream 0257f64bdac7 351cb5cf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/11 16:20 upstream b29fb8829bff 2d88ab01 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/11 13:29 upstream b4f0dd314b39 86914af9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/11 12:26 upstream b4f0dd314b39 86914af9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/11 10:34 upstream b4f0dd314b39 86914af9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/11 00:22 upstream b4f0dd314b39 4683d576 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/10 09:53 upstream 1f318b96cc84 6972f302 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/10 05:34 upstream 1f318b96cc84 6972f302 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/03/03 01:01 upstream af4e9ef3d784 28b83e23 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/02/07 17:50 upstream 2687c848e578 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/02/07 09:19 upstream 2687c848e578 f20fc9f9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/02/02 09:11 upstream 18f7fcd5e69a 018ebef2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in netdev_run_todo
2026/01/23 09:47 upstream c072629f05d7 82c9c083 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/01/14 12:25 upstream c537e12daeec d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/01/12 18:08 upstream 0f61b1860cc3 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/01/11 23:53 upstream 755bc1335e3b d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/01/06 15:03 upstream 7f98ab9da046 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/01/06 02:07 upstream 7f98ab9da046 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/01/05 09:45 upstream 3609fa95fb0f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/01/05 05:10 upstream 54e82e93ca93 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/01/03 09:35 upstream 9b0436804460 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/01/01 08:26 upstream 9528d5c091c5 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2026/01/01 03:29 upstream 9528d5c091c5 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/31 14:17 upstream c8ebd433459b d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/31 13:06 upstream c8ebd433459b d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in netdev_run_todo
2025/12/31 08:39 upstream dbf8fe85a16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/28 11:40 upstream d26143bb38e2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/27 04:22 upstream 3f0e9c8cefa9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/26 02:21 upstream ccd1cdca5cd4 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/20 20:15 upstream d8ba32c5a460 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/20 17:08 upstream dd9b004b7ff3 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/12 14:05 upstream 187d0801404f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/12 01:28 upstream d358e5254674 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/10 11:51 upstream c9b47175e913 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/06 17:54 upstream 416f99c3b16f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/04 06:08 upstream a619fe35ab41 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/12/03 09:38 upstream 3f9f0252130e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/11/29 12:06 upstream 19eef1d98eed d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/11/27 14:09 upstream 4941a17751c9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/11/27 06:00 upstream 4941a17751c9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netdev_run_todo
2025/07/21 21:41 upstream 89be9a83ccf1 0b3788a0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in netdev_run_todo
2024/10/13 22:33 upstream ba01565ced22 084d8178 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netdev_run_todo
2024/10/06 16:49 upstream 8f602276d390 d7906eff .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netdev_run_todo
2024/09/27 16:51 upstream 075dbe9f6e3c 2b1784d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in netdev_run_todo
2025/07/06 03:02 upstream 05df91921da6 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 INFO: task hung in netdev_run_todo
2025/02/25 10:53 upstream d082ecbc71e9 d34966d1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm64-compat INFO: task hung in netdev_run_todo
2024/09/21 15:34 upstream 1868f9d0260e 6f888b75 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm64 INFO: task hung in netdev_run_todo
2026/02/23 16:33 net d4f687fbbce4 305c0ec5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in netdev_run_todo
2025/09/23 05:22 net-next 78e87f9d5358 0ac7291c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in netdev_run_todo
2025/07/01 18:35 linux-next 1343433ed389 ffe4b334 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netdev_run_todo
2025/08/22 05:15 git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git for-next 8f5ae30d69d7 bf27483f .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-riscv64 INFO: task hung in netdev_run_todo
* Struck through repros no longer work on HEAD.