INFO: task hung in linkwatch_event (2)

Status: upstream: reported C repro on 2020/03/11 20:12
Reported-by: syzbot+2e5d791c70d2a810b3a5@syzkaller.appspotmail.com
First crash: 2325d, last: 1237d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Similar bugs (20)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in linkwatch_event (2) 1 1 530d 530d 0/3 auto-obsoleted due to no activity on 2025/05/19 15:08
linux-6.1 INFO: task hung in linkwatch_event (5) 1 syz error 8 100d 272d 0/3 auto-obsoleted due to no activity on 2026/07/24 12:40
linux-6.1 INFO: task hung in linkwatch_event (4) 1 syz 7 406d 498d 0/3 auto-obsoleted due to no activity on 2025/09/20 14:43
android-414 INFO: task hung in linkwatch_event 1 C 7 2442d 2661d 0/1 public: reported C repro on 2019/04/10 16:14
linux-6.6 INFO: task hung in linkwatch_event origin:lts-only 1 C inconclusive 30 7d05h 385d 0/2 upstream: reported C repro on 2025/07/04 13:16
linux-4.14 INFO: task hung in linkwatch_event (2) 1 1 1463d 1463d 0/1 auto-obsoleted due to no activity on 2022/11/19 11:58
android-44 INFO: task hung in linkwatch_event 1 6 2878d 3023d 0/2 auto-closed as invalid on 2019/03/05 13:11
linux-5.15 INFO: task hung in linkwatch_event 1 84 629d 925d 0/3 auto-obsoleted due to no activity on 2025/01/11 00:55
upstream INFO: task hung in linkwatch_event (4) prio:low net 1 C done 3642 5h51m 727d 0/29 upstream: reported C repro on 2024/07/27 06:21
linux-5.15 INFO: task hung in linkwatch_event (3) 1 8 5d18h 306d 0/3 upstream: reported on 2025/09/20 20:03
upstream INFO: task hung in linkwatch_event net 1 C 82 2470d 3082d 0/29 closed as dup on 2018/02/14 15:33
linux-4.14 INFO: task hung in linkwatch_event 1 5 2146d 2273d 0/1 auto-closed as invalid on 2021/01/05 01:42
upstream INFO: task hung in linkwatch_event (2) net 1 C done done 1033 1551d 2277d 20/29 fixed on 2022/05/13 11:13
linux-4.19 INFO: task hung in linkwatch_event 1 3 2479d 2593d 0/1 auto-closed as invalid on 2020/02/07 01:11
upstream INFO: task hung in linkwatch_event (3) net 1 1634 745d 1339d 26/29 fixed on 2024/07/09 19:14
linux-4.14 INFO: task hung in linkwatch_event (3) 1 2 1297d 1298d 0/1 upstream: reported on 2023/01/03 10:49
android-49 INFO: task hung in linkwatch_event 1 13 2641d 2658d 0/3 auto-closed as invalid on 2019/10/25 08:50
linux-6.1 INFO: task hung in linkwatch_event (2) 1 32 680d 794d 0/3 auto-obsoleted due to no activity on 2024/11/21 00:32
linux-6.1 INFO: task hung in linkwatch_event 1 2 1083d 1199d 0/3 auto-obsoleted due to no activity on 2023/11/14 00:59
linux-6.1 INFO: task hung in linkwatch_event (3) 1 1 605d 605d 0/3 auto-obsoleted due to no activity on 2025/03/05 15:51
▶ ▼ Fix bisection attempts (6)
Created Duration User Patch Repo Result
2022/06/17 21:19 17m bisect fix linux-4.19.y error job log
2021/07/11 15:28 30m bisect fix linux-4.19.y OK (0) job log log
2021/05/20 08:53 35m bisect fix linux-4.19.y OK (0) job log log
2021/04/16 23:23 27m bisect fix linux-4.19.y OK (0) job log log
2021/03/09 17:52 29m bisect fix linux-4.19.y OK (0) job log log
2021/01/08 09:58 28m bisect fix linux-4.19.y OK (0) job log log

Sample crash report:
IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
INFO: task kworker/0:1:14 blocked for more than 140 seconds.
      Not tainted 4.19.157-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/0:1     D26552    14      2 0x80000000
Workqueue: events linkwatch_event
Call Trace:
 context_switch kernel/sched/core.c:2828 [inline]
 __schedule+0x887/0x2040 kernel/sched/core.c:3517
 schedule+0x8d/0x1b0 kernel/sched/core.c:3561
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3619
 __mutex_lock_common kernel/locking/mutex.c:1002 [inline]
 __mutex_lock+0x647/0x1260 kernel/locking/mutex.c:1072
 linkwatch_event+0xb/0x60 net/core/link_watch.c:236
 process_one_work+0x864/0x1570 kernel/workqueue.c:2155
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
INFO: task kworker/0:0:8130 blocked for more than 140 seconds.
      Not tainted 4.19.157-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/0:0     D27416  8130      2 0x80000000
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 context_switch kernel/sched/core.c:2828 [inline]
 __schedule+0x887/0x2040 kernel/sched/core.c:3517
 schedule+0x8d/0x1b0 kernel/sched/core.c:3561
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3619
 __mutex_lock_common kernel/locking/mutex.c:1002 [inline]
 __mutex_lock+0x647/0x1260 kernel/locking/mutex.c:1072
 addrconf_dad_work+0x9c/0x10a0 net/ipv6/addrconf.c:3988
 process_one_work+0x864/0x1570 kernel/workqueue.c:2155
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Showing all locks held in the system:
3 locks held by kworker/0:1/14:
 #0: 00000000e55d9845 ((wq_completion)"events"){+.+.}, at: process_one_work+0x767/0x1570 kernel/workqueue.c:2126
 #1: 00000000489dd410 ((linkwatch_work).work){+.+.}, at: process_one_work+0x79c/0x1570 kernel/workqueue.c:2130
 #2: 00000000fb70e3fd (rtnl_mutex){+.+.}, at: linkwatch_event+0xb/0x60 net/core/link_watch.c:236
3 locks held by kworker/1:1/25:
 #0: 00000000cf9cbaaa ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: process_one_work+0x767/0x1570 kernel/workqueue.c:2126
 #1: 0000000005dfb04d ((addr_chk_work).work){+.+.}, at: process_one_work+0x79c/0x1570 kernel/workqueue.c:2130
 #2: 00000000fb70e3fd (rtnl_mutex){+.+.}, at: addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4475
1 lock held by khungtaskd/1566:
 #0: 0000000035d44def (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
1 lock held by in:imklog/7779:
 #0: 00000000a612ab87 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767
3 locks held by kworker/0:0/8130:
 #0: 00000000cf9cbaaa ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: process_one_work+0x767/0x1570 kernel/workqueue.c:2126
 #1: 000000007c79bb18 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}, at: process_one_work+0x79c/0x1570 kernel/workqueue.c:2130
 #2: 00000000fb70e3fd (rtnl_mutex){+.+.}, at: addrconf_dad_work+0x9c/0x10a0 net/ipv6/addrconf.c:3988
4 locks held by syz-executor805/8150:

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

NMI backtrace for cpu 0
CPU: 0 PID: 1566 Comm: khungtaskd Not tainted 4.19.157-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2fe lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
 watchdog+0x991/0xe60 kernel/hung_task.c:287
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8150 Comm: syz-executor805 Not tainted 4.19.157-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ieee80211_chanctx_radar_detect+0x258/0x390 net/mac80211/util.c:3492
Code: 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 74 08 3c 03 0f 8e 00 01 00 00 8b 8b 00 10 00 00 b8 01 00 00 00 48 d3 e0 41 09 c4 <e8> 53 5f a1 f9 48 8d bb f8 07 00 00 48 89 f8 48 c1 e8 03 42 80 3c
RSP: 0018:ffff88809642f3a0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff8880abd40ec0 RCX: ffffffff87c36fce
RDX: 0000000000000000 RSI: ffff8880b07d6600 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8880ab2c7920 R14: dffffc0000000000 R15: 0000000000000000
FS:  0000000000b7c880(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005588cea94f00 CR3: 00000000a573f000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ieee80211_check_combinations+0x3b8/0x810 net/mac80211/util.c:3552
 ieee80211_check_concurrent_iface+0x46d/0x650 net/mac80211/iface.c:312
 ieee80211_runtime_change_iftype net/mac80211/iface.c:1541 [inline]
 ieee80211_if_change_type+0x27b/0x5f0 net/mac80211/iface.c:1579
 ieee80211_change_iface+0x26/0x220 net/mac80211/cfg.c:157
 rdev_change_virtual_intf net/wireless/rdev-ops.h:69 [inline]
 cfg80211_change_iface+0x2e1/0x1530 net/wireless/util.c:936
 nl80211_set_interface+0x661/0x830 net/wireless/nl80211.c:3205
 genl_family_rcv_msg+0x642/0xc40 net/netlink/genetlink.c:602
 genl_rcv_msg+0xbf/0x160 net/netlink/genetlink.c:627
 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:638
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:632
 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115
 __sys_sendmsg net/socket.c:2153 [inline]
 __do_sys_sendmsg net/socket.c:2162 [inline]
 __se_sys_sendmsg net/socket.c:2160 [inline]
 __x64_sys_sendmsg+0x132/0x220 net/socket.c:2160
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x442449
Code: e8 4c ff 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc13fd0128 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000442449
RDX: 0000000000000000 RSI: 0000000020000340 RDI: 0000000000000004
RBP: 000000306e616c77 R08: 00000000004002e0 R09: 00000000004002e0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402fb0
R13: 0000000000403040 R14: 0000000000000000 R15: 0000000000000000
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.239 msecs

Crashes (217):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/11/12 08:42 linux-4.19.y 31acccdc8774 cca87986 .config console log report syz C ci2-linux-4-19
2023/03/05 04:28 linux-4.19.y 3f8a27f9e27b f8902b57 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2023/02/25 19:54 linux-4.19.y 3f8a27f9e27b ee50e71c .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2023/02/09 18:04 linux-4.19.y 3f8a27f9e27b 07980f9d .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2023/02/06 14:18 linux-4.19.y 3f8a27f9e27b 0a9c11b6 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2023/02/03 13:17 linux-4.19.y 3f8a27f9e27b 1b2f701a .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2023/01/14 12:23 linux-4.19.y 3f8a27f9e27b a63719e7 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2023/01/05 16:26 linux-4.19.y 3f8a27f9e27b 1dac8c7a .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2023/01/03 12:07 linux-4.19.y 3f8a27f9e27b f0036e18 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/12/27 15:42 linux-4.19.y 3f8a27f9e27b 44712fbc .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/12/14 14:31 linux-4.19.y 3f8a27f9e27b b18f0a64 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/12/13 18:38 linux-4.19.y 3f8a27f9e27b f6511626 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/12/13 14:32 linux-4.19.y 3f8a27f9e27b 67be1ae7 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/12/01 11:28 linux-4.19.y 3f8a27f9e27b 4c2a66e8 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/11/27 21:43 linux-4.19.y 3f8a27f9e27b f4470a7b .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/11/26 06:17 linux-4.19.y 3f8a27f9e27b f4470a7b .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/11/25 20:15 linux-4.19.y 3f8a27f9e27b f4470a7b .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/11/23 11:07 linux-4.19.y 3f8a27f9e27b 52fdf57a .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/11/20 18:26 linux-4.19.y 3f8a27f9e27b 5bb70014 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/11/16 00:25 linux-4.19.y 3f8a27f9e27b 3a127a31 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/11/11 21:55 linux-4.19.y 3f8a27f9e27b f42ee5d8 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/11/09 02:50 linux-4.19.y 3f8a27f9e27b 5fa28208 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/11/07 13:34 linux-4.19.y 3f8a27f9e27b a779b11a .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/10/26 20:18 linux-4.19.y 3f8a27f9e27b 86777b7f .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/10/24 16:51 linux-4.19.y 3f8a27f9e27b faae2fda .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/10/23 12:14 linux-4.19.y 3f8a27f9e27b 23bf86af .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/10/15 09:44 linux-4.19.y 3f8a27f9e27b 67cb024c .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/10/10 23:32 linux-4.19.y 3f8a27f9e27b 5bcf0c31 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/10/02 06:28 linux-4.19.y 3f8a27f9e27b feb56351 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/25 03:42 linux-4.19.y 3f8a27f9e27b 0042f2b4 .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/20 17:51 linux-4.19.y 3f8a27f9e27b c4b8ccfd .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/20 16:40 linux-4.19.y 3f8a27f9e27b c4b8ccfd .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/20 14:57 linux-4.19.y 3f8a27f9e27b 7c41a9ba .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/19 13:26 linux-4.19.y 3f8a27f9e27b dd9a85ff .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/18 17:51 linux-4.19.y 3f8a27f9e27b dd9a85ff .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/15 08:06 linux-4.19.y 3f8a27f9e27b dd9a85ff .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/14 12:36 linux-4.19.y 3f8a27f9e27b b884348d .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/10 10:43 linux-4.19.y 3f8a27f9e27b 356d8217 .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/09 23:30 linux-4.19.y 3f8a27f9e27b 356d8217 .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/09 20:58 linux-4.19.y 3f8a27f9e27b 90058bdc .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/06 15:58 linux-4.19.y 3f8a27f9e27b 65aea2b9 .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/09/01 19:48 linux-4.19.y 3f8a27f9e27b 86c46e46 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/08/31 08:41 linux-4.19.y 3f8a27f9e27b 4a380809 .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/08/29 13:06 linux-4.19.y 3f8a27f9e27b 94da0b6b .config console log report info [disk image] [vmlinux] ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/08/28 10:52 linux-4.19.y 3f8a27f9e27b 07177916 .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/08/28 06:15 linux-4.19.y 3f8a27f9e27b 07177916 .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/08/16 00:52 linux-4.19.y 3f8a27f9e27b 7a7cb304 .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/08/11 19:29 linux-4.19.y 3f8a27f9e27b 787ed7e0 .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2022/08/10 05:44 linux-4.19.y 3f8a27f9e27b c2a623d6 .config console log report info ci2-linux-4-19 INFO: task hung in linkwatch_event
2020/12/09 09:48 linux-4.19.y 4abf26854aad 99917735 .config console log report info ci2-linux-4-19
2020/03/11 20:11 linux-4.19.y 569209711609 e103bc9e .config console log report ci2-linux-4-19
* Struck through repros no longer work on HEAD.