[v6.1] INFO: task hung in addrconf_dad_work (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 81e1dc2f7001 Linux 6.1.79
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15b60122180000
kernel config: https://syzkaller.appspot.com/x/.config?x=1f1b2df4155f9cc0
dashboard link: https://syzkaller.appspot.com/bug?extid=e05c903385afc8df6c9b
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c15e68f002df/disk-81e1dc2f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/48d036ef2f3c/vmlinux-81e1dc2f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f372bf435776/bzImage-81e1dc2f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e05c90...@syzkaller.appspotmail.com

INFO: task kworker/0:1:14 blocked for more than 143 seconds.
Not tainted 6.1.79-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:1 state:D stack:23264 pid:14 ppid:2 flags:0x00004000
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x142d/0x4550 kernel/sched/core.c:6558
schedule+0xbf/0x180 kernel/sched/core.c:6634
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6693
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b9/0xd80 kernel/locking/mutex.c:747
addrconf_dad_work+0xcc/0x16b0 net/ipv6/addrconf.c:4098
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
INFO: task kworker/0:5:3602 blocked for more than 143 seconds.
Not tainted 6.1.79-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:5 state:D stack:23672 pid:3602 ppid:2 flags:0x00004000
Workqueue: events linkwatch_event
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x142d/0x4550 kernel/sched/core.c:6558
schedule+0xbf/0x180 kernel/sched/core.c:6634
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6693
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b9/0xd80 kernel/locking/mutex.c:747
linkwatch_event+0xa/0x50 net/core/link_watch.c:263
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
INFO: task syz-executor.3:7047 blocked for more than 144 seconds.
Not tainted 6.1.79-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.3 state:D stack:21736 pid:7047 ppid:1 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x142d/0x4550 kernel/sched/core.c:6558
schedule+0xbf/0x180 kernel/sched/core.c:6634
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6693
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b9/0xd80 kernel/locking/mutex.c:747
rtnl_lock net/core/rtnetlink.c:74 [inline]
rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
netlink_rcv_skb+0x1cd/0x410 net/netlink/af_netlink.c:2508
netlink_unicast_kernel net/netlink/af_netlink.c:1326 [inline]
netlink_unicast+0x7d8/0x970 net/netlink/af_netlink.c:1352
netlink_sendmsg+0xa26/0xd60 net/netlink/af_netlink.c:1874
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:730 [inline]
__sys_sendto+0x480/0x600 net/socket.c:2148
__do_sys_sendto net/socket.c:2160 [inline]
__se_sys_sendto net/socket.c:2156 [inline]
__x64_sys_sendto+0xda/0xf0 net/socket.c:2156
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f431287fa9c
RSP: 002b:00007fffaf939310 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f43134d4620 RCX: 00007f431287fa9c
RDX: 0000000000000020 RSI: 00007f43134d4670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007fffaf939364 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f43134d4670 R15: 0000000000000000
</TASK>
INFO: task syz-executor.4:7061 blocked for more than 144 seconds.
Not tainted 6.1.79-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.4 state:D stack:21736 pid:7061 ppid:1 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x142d/0x4550 kernel/sched/core.c:6558
schedule+0xbf/0x180 kernel/sched/core.c:6634
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6693
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b9/0xd80 kernel/locking/mutex.c:747
rtnl_lock net/core/rtnetlink.c:74 [inline]
rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
netlink_rcv_skb+0x1cd/0x410 net/netlink/af_netlink.c:2508
netlink_unicast_kernel net/netlink/af_netlink.c:1326 [inline]
netlink_unicast+0x7d8/0x970 net/netlink/af_netlink.c:1352
netlink_sendmsg+0xa26/0xd60 net/netlink/af_netlink.c:1874
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:730 [inline]
__sys_sendto+0x480/0x600 net/socket.c:2148
__do_sys_sendto net/socket.c:2160 [inline]
__se_sys_sendto net/socket.c:2156 [inline]
__x64_sys_sendto+0xda/0xf0 net/socket.c:2156
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ff2b8a7fa9c
RSP: 002b:00007ffc27954c40 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007ff2b96d4620 RCX: 00007ff2b8a7fa9c
RDX: 000000000000006c RSI: 00007ff2b96d4670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffc27954c94 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007ff2b96d4670 R15: 0000000000000000
</TASK>
INFO: task syz-executor.0:7075 blocked for more than 145 seconds.
Not tainted 6.1.79-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0 state:D stack:21736 pid:7075 ppid:1 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x142d/0x4550 kernel/sched/core.c:6558
schedule+0xbf/0x180 kernel/sched/core.c:6634
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6693
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b9/0xd80 kernel/locking/mutex.c:747
rtnl_lock net/core/rtnetlink.c:74 [inline]
rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
netlink_rcv_skb+0x1cd/0x410 net/netlink/af_netlink.c:2508
netlink_unicast_kernel net/netlink/af_netlink.c:1326 [inline]
netlink_unicast+0x7d8/0x970 net/netlink/af_netlink.c:1352
netlink_sendmsg+0xa26/0xd60 net/netlink/af_netlink.c:1874
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:730 [inline]
__sys_sendto+0x480/0x600 net/socket.c:2148
__do_sys_sendto net/socket.c:2160 [inline]
__se_sys_sendto net/socket.c:2156 [inline]
__x64_sys_sendto+0xda/0xf0 net/socket.c:2156
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f81ec07fa9c
RSP: 002b:00007ffdb6c4fa10 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f81eccd4620 RCX: 00007f81ec07fa9c
RDX: 0000000000000020 RSI: 00007f81eccd4670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffdb6c4fa64 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f81eccd4670 R15: 0000000000000000
</TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8d12aa90 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:516
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8d12b290 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:516
3 locks held by kworker/0:1/14:
#0: ffff88814b1e2938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1: ffffc90000137d20 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#2: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xcc/0x16b0 net/ipv6/addrconf.c:4098
1 lock held by khungtaskd/28:
#0: ffffffff8d12a8c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:319 [inline]
#0: ffffffff8d12a8c0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:760 [inline]
#0: ffffffff8d12a8c0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6494
5 locks held by kworker/u4:2/41:
#0: ffff888012616938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1: ffffc90000b27d20 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#2: ffffffff8e288c10 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0xf1/0xb60 net/core/net_namespace.c:563
#3: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: default_device_exit_batch+0xe5/0x9d0 net/core/dev.c:11377
#4: ffffffff8d12feb8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
#4: ffffffff8d12feb8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3b0/0x8a0 kernel/rcu/tree_exp.h:949
3 locks held by kworker/0:2/151:
#0: ffff888012470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1: ffffc90002e2fd20 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#2: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xa/0x20 net/switchdev/switchdev.c:75
2 locks held by getty/3303:
#0: ffff88814afb4098 (&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/0:5/3602:
#0: ffff888012470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1: ffffc90004f2fd20 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#2: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263
3 locks held by kworker/1:4/3603:
#0: ffff88814b1e2938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1: ffffc90004f3fd20 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#2: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0x15/0x30 net/ipv6/addrconf.c:4639
2 locks held by kworker/1:7/3637:
#0: ffff888012472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1: ffffc9000533fd20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
1 lock held by syz-executor.3/7047:
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
1 lock held by syz-executor.4/7061:
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
1 lock held by syz-executor.0/7075:
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
1 lock held by syz-executor.3/7635:
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
1 lock held by syz-executor.4/7646:
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
1 lock held by syz-executor.0/7657:
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
1 lock held by syz-executor.3/8210:
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
1 lock held by syz-executor.4/8221:
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
1 lock held by syz-executor.0/8237:
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e294e68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6119
1 lock held by syz-executor.1/8518:
3 locks held by syz-executor.2/8525:
1 lock held by syz-executor.2/8534:
2 locks held by syz-executor.1/8542:
1 lock held by syz-executor.2/8546:
3 locks held by syz-executor.1/8551:
2 locks held by syz-executor.2/8557:
2 locks held by syz-executor.2/8568:
1 lock held by syz-executor.1/8578:
2 locks held by syz-executor.1/8585:
1 lock held by syz-executor.1/8598:
3 locks held by syz-executor.1/8608:
4 locks held by syz-executor.1/8618:
3 locks held by syz-executor.2/8622:
2 locks held by syz-executor.1/8628:
2 locks held by syz-executor.2/8635:
2 locks held by syz-executor.1/8642:
2 locks held by syz-executor.2/8644:
2 locks held by syz-executor.1/8653:
2 locks held by syz-executor.2/8656:
2 locks held by syz-executor.1/8662:
2 locks held by syz-executor.2/8667:
2 locks held by syz-executor.1/8676:
3 locks held by syz-executor.2/8679:
2 locks held by syz-executor.1/8685:
3 locks held by syz-executor.2/8691:
2 locks held by syz-executor.1/8696:
2 locks held by syz-executor.2/8701:
3 locks held by syz-executor.1/8708:
3 locks held by syz-executor.2/8713:
3 locks held by syz-executor.2/8721:
2 locks held by syz-executor.1/8723:
2 locks held by syz-executor.2/8732:
2 locks held by syz-executor.1/8736:
2 locks held by syz-executor.2/8743:
2 locks held by syz-executor.1/8748:
2 locks held by syz-executor.2/8753:
2 locks held by syz-executor.1/8758:

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted 6.1.79-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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+0xf88/0xfd0 kernel/hung_task.c:377
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 3626 Comm: kworker/u4:5 Not tainted 6.1.79-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Workqueue: bat_events batadv_nc_worker
RIP: 0010:__lock_acquire+0x5/0x1f80 kernel/locking/lockdep.c:4907
Code: e9 26 ff ff ff 48 8b 0c 24 80 e1 07 80 c1 03 38 c1 7c 94 48 8b 3c 24 e8 59 9c 77 00 eb 89 0f 1f 80 00 00 00 00 55 41 57 41 56 <41> 55 41 54 53 48 81 ec 88 00 00 00 44 89 cb 45 89 c7 41 89 cc 89
RSP: 0018:ffffc900052ffa40 EFLAGS: 00000006
RAX: 0000000000000001 RBX: ffffc900052ffae0 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8d12a8c0
RBP: ffffc900052ffbe0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000a5ff58
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000246
FS: 0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd2a65d7440 CR3: 000000000ce8e000 CR4: 00000000003506e0
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:5662
rcu_lock_acquire include/linux/rcupdate.h:319 [inline]
rcu_read_lock include/linux/rcupdate.h:760 [inline]
batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
batadv_nc_worker+0xe8/0x610 net/batman-adv/network-coding.c:719
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>


---
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syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup