syzbot


INFO: task hung in linkwatch_event

Status: auto-obsoleted due to no activity on 2023/11/14 00:59
Reported-by: syzbot+46d6df234bd389e04f3d@syzkaller.appspotmail.com
First crash: 610d, last: 494d
Similar bugs (15)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-414 INFO: task hung in linkwatch_event C 7 1853d 2073d 0/1 public: reported C repro on 2019/04/10 16:14
linux-4.14 INFO: task hung in linkwatch_event (2) 1 874d 874d 0/1 auto-obsoleted due to no activity on 2022/11/19 11:58
android-44 INFO: task hung in linkwatch_event 6 2289d 2434d 0/2 auto-closed as invalid on 2019/03/05 13:11
linux-5.15 INFO: task hung in linkwatch_event 84 40d 336d 0/3 upstream: reported on 2024/01/11 11:32
upstream INFO: task hung in linkwatch_event (4) net C done 2409 3h06m 138d 0/28 upstream: reported C repro on 2024/07/27 06:21
upstream INFO: task hung in linkwatch_event net C 82 1881d 2493d 0/28 closed as dup on 2018/02/14 15:33
linux-4.14 INFO: task hung in linkwatch_event 5 1557d 1684d 0/1 auto-closed as invalid on 2021/01/05 01:42
linux-4.19 INFO: task hung in linkwatch_event (2) C error 217 648d 1737d 0/1 upstream: reported C repro on 2020/03/11 20:12
upstream INFO: task hung in linkwatch_event (2) net C done done 1033 962d 1688d 20/28 fixed on 2022/05/13 11:13
linux-4.19 INFO: task hung in linkwatch_event 3 1890d 2004d 0/1 auto-closed as invalid on 2020/02/07 01:11
upstream INFO: task hung in linkwatch_event (3) net 1634 156d 751d 26/28 fixed on 2024/07/09 19:14
linux-4.14 INFO: task hung in linkwatch_event (3) 2 708d 709d 0/1 upstream: reported on 2023/01/03 10:49
android-49 INFO: task hung in linkwatch_event 13 2052d 2069d 0/3 auto-closed as invalid on 2019/10/25 08:50
linux-6.1 INFO: task hung in linkwatch_event (2) 32 91d 206d 0/3 auto-obsoleted due to no activity on 2024/11/21 00:32
linux-6.1 INFO: task hung in linkwatch_event (3) 1 17d 17d 0/3 upstream: reported on 2024/11/25 15:51

Sample crash report:
INFO: task kworker/0:7:31139 blocked for more than 143 seconds.
      Not tainted 6.1.43-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:7     state:D stack:22912 pid:31139 ppid:2      flags:0x00004000
Workqueue: events linkwatch_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0x132c/0x4330 kernel/sched/core.c:6554
 schedule+0xbf/0x180 kernel/sched/core.c:6630
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6689
 __mutex_lock_common+0xe2b/0x2520 kernel/locking/mutex.c:679
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
 linkwatch_event+0xa/0x50 net/core/link_watch.c:263
 process_one_work+0x8aa/0x11f0 kernel/workqueue.c:2292
 worker_thread+0xa5f/0x1210 kernel/workqueue.c:2439
 kthread+0x26e/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8d129930 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:516
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8d12a130 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:516
1 lock held by khungtaskd/28:
 #0: ffffffff8d129760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3300:
 #0: ffff888029279098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc900031262f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a7/0x1db0 drivers/tty/n_tty.c:2188
3 locks held by kworker/0:7/31139:
 #0: ffff888012464d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x77a/0x11f0
 #1: ffffc90009e17d20 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7bd/0x11f0 kernel/workqueue.c:2267
 #2: ffffffff8e297ea8 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263
3 locks held by kworker/1:8/17497:
 #0: ffff88814b6b6138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x77a/0x11f0
 #1: ffffc90015ddfd20 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7bd/0x11f0 kernel/workqueue.c:2267
 #2: ffffffff8e297ea8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0x15/0x30 net/ipv6/addrconf.c:4634
3 locks held by kworker/0:18/20375:
 #0: ffff88814b6b6138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x77a/0x11f0
 #1: ffffc90005e6fd20 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7bd/0x11f0 kernel/workqueue.c:2267
 #2: ffffffff8e297ea8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0x15/0x30 net/ipv6/addrconf.c:4634
2 locks held by syz-executor.5/28171:
2 locks held by syz-executor.0/28187:
 #0: ffffffff8e300050 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:860
 #1: ffffffff8e297ea8 (rtnl_mutex){+.+.}-{3:3}, at: ethnl_default_doit+0x4fa/0xcc0 net/ethtool/netlink.c:383
1 lock held by syz-executor.1/28190:
 #0: ffffffff8e297ea8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8e297ea8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x720/0xf00 net/core/rtnetlink.c:6100
1 lock held by syz-executor.5/28208:
 #0: ffffffff8e297ea8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8e297ea8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x720/0xf00 net/core/rtnetlink.c:6100
1 lock held by syz-executor.5/28218:
 #0: ffffffff8e297ea8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8e297ea8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x720/0xf00 net/core/rtnetlink.c:6100

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 6.1.43-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 nmi_cpu_backtrace+0x4e1/0x560 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1b0/0x3f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf18/0xf60 kernel/hung_task.c:377
 kthread+0x26e/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 7091 Comm: kworker/u4:2 Not tainted 6.1.43-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Workqueue: bat_events batadv_nc_worker
RIP: 0010:hlock_class kernel/locking/lockdep.c:223 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4755 [inline]
RIP: 0010:__lock_acquire+0x759/0x1f80 kernel/locking/lockdep.c:5006
Code: 91 48 c1 e8 03 48 89 44 24 50 48 c7 c0 a8 a4 73 8e 48 c1 e8 03 48 89 44 24 68 4c 89 ed 41 83 fc 31 0f 83 df 01 00 00 48 89 e8 <48> c1 e8 03 0f b6 04 10 84 c0 0f 85 2f 01 00 00 41 8b 5d 00 81 e3
RSP: 0018:ffffc9000c6979a0 EFLAGS: 00000097
RAX: ffff8880883ba8c0 RBX: ffff8880883ba884 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: ffff8880883ba8a0 RDI: ffffffff90497220
RBP: ffff8880883ba8c0 R08: dffffc0000000000 R09: fffffbfff2092e45
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000000
R13: ffff8880883ba8c0 R14: 0000000000000000 R15: 1ffff11011077504
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c00b0e9000 CR3: 000000000ce8e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:306
 rcu_read_lock include/linux/rcupdate.h:747 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
 batadv_nc_worker+0xc1/0x5b0 net/batman-adv/network-coding.c:719
 process_one_work+0x8aa/0x11f0 kernel/workqueue.c:2292
 worker_thread+0xa5f/0x1210 kernel/workqueue.c:2439
 kthread+0x26e/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/08/06 00:59 linux-6.1.y 52a953d0934b 4ffcc9ef .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in linkwatch_event
2023/04/12 08:24 linux-6.1.y 543aff194ab6 1a1596b6 .config console log report info ci2-linux-6-1-kasan INFO: task hung in linkwatch_event
* Struck through repros no longer work on HEAD.