INFO: task hung in ip6gre_exit_net

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 01364dad Linux 4.14.174
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13c4e65be00000
kernel config: https://syzkaller.appspot.com/x/.config?x=664dd71881ab2b2d
dashboard link: https://syzkaller.appspot.com/bug?extid=2ec77a98bfe0e869dae4
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+2ec77a...@syzkaller.appspotmail.com

NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
INFO: task kworker/u4:5:2371 blocked for more than 140 seconds.
Not tainted 4.14.174-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:5 D27248 2371 2 0x80000000
Workqueue: netns cleanup_net
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
ip6gre_exit_net+0x70/0x580 net/ipv6/ip6_gre.c:1206
ops_exit_list.isra.0+0x9d/0x140 net/core/net_namespace.c:142
cleanup_net+0x3bb/0x820 net/core/net_namespace.c:484
process_one_work+0x813/0x1540 kernel/workqueue.c:2116
worker_thread+0x5d1/0x1070 kernel/workqueue.c:2250
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
INFO: task kworker/1:2:3335 blocked for more than 140 seconds.
Not tainted 4.14.174-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/1:2 D26624 3335 2 0x80000000
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
addrconf_dad_work+0x90/0xfc0 net/ipv6/addrconf.c:3913
process_one_work+0x813/0x1540 kernel/workqueue.c:2116
worker_thread+0x5d1/0x1070 kernel/workqueue.c:2250
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
INFO: task syz-executor.4:10949 blocked for more than 140 seconds.
Not tainted 4.14.174-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D25568 10949 7555 0x00000004
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
exp_funnel_lock kernel/rcu/tree_exp.h:295 [inline]
_synchronize_rcu_expedited+0x669/0x820 kernel/rcu/tree_exp.h:596
synchronize_net+0x2b/0x40 net/core/dev.c:8233
rollback_registered_many+0x7a0/0xa70 net/core/dev.c:7236
unregister_netdevice_many.part.0+0x16/0x1d0 net/core/dev.c:8278
unregister_netdevice_many+0x36/0x50 net/core/dev.c:8277
rtnl_newlink+0x13c0/0x1720 net/core/rtnetlink.c:2770
rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4315
netlink_rcv_skb+0x127/0x370 net/netlink/af_netlink.c:2433
netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
netlink_unicast+0x437/0x620 net/netlink/af_netlink.c:1313
netlink_sendmsg+0x733/0xbe0 net/netlink/af_netlink.c:1878
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xc5/0x100 net/socket.c:656
___sys_sendmsg+0x349/0x840 net/socket.c:2062
__sys_sendmmsg+0x129/0x330 net/socket.c:2152
SYSC_sendmmsg net/socket.c:2183 [inline]
SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007fdeddfb7c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007fdeddfb86d4 RCX: 000000000045c849
RDX: 0492492492492627 RSI: 00000000200000c0 RDI: 0000000000000006
RBP: 000000000076c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008d6 R14: 00000000004cb798 R15: 000000000076c04c
INFO: task syz-executor.5:10952 blocked for more than 140 seconds.
Not tainted 4.14.174-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5 D29856 10952 7550 0x00000004
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
dev_ioctl+0x27c/0xcb0 net/core/dev_ioctl.c:421
sock_do_ioctl+0x8c/0xa0 net/socket.c:981
sock_ioctl+0x28d/0x450 net/socket.c:1071
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007fb22d2d1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb22d2d26d4 RCX: 000000000045c849
RDX: 0000000000400200 RSI: 0000000000008912 RDI: 0000000000000005
RBP: 000000000076bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000040d R14: 00000000004c6adf R15: 000000000076bfac
INFO: task syz-executor.5:10981 blocked for more than 140 seconds.
Not tainted 4.14.174-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5 D29120 10981 7550 0x00000004
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
genl_lock net/netlink/genetlink.c:33 [inline]
genl_rcv_msg+0x112/0x140 net/netlink/genetlink.c:623
netlink_rcv_skb+0x127/0x370 net/netlink/af_netlink.c:2433
genl_rcv+0x24/0x40 net/netlink/genetlink.c:636
netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
netlink_unicast+0x437/0x620 net/netlink/af_netlink.c:1313
netlink_sendmsg+0x733/0xbe0 net/netlink/af_netlink.c:1878
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xc5/0x100 net/socket.c:656
___sys_sendmsg+0x70a/0x840 net/socket.c:2062
__sys_sendmsg+0xa3/0x120 net/socket.c:2096
SYSC_sendmsg net/socket.c:2107 [inline]
SyS_sendmsg+0x27/0x40 net/socket.c:2103
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x416501
RSP: 002b:00007fb22d2b09c0 EFLAGS: 00000293 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb22d2b0a58 RCX: 0000000000416501
RDX: 0000000000000000 RSI: 00007fb22d2b0a00 RDI: 0000000000000008
RBP: 0000000000000008 R08: 0000000000000009 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00007fb22d2b0a40
R13: 0000000000000bc6 R14: 00000000004d8100 R15: 000000000076c04c
INFO: task syz-executor.0:10964 blocked for more than 140 seconds.
Not tainted 4.14.174-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0 D27072 10964 7553 0x00000004
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
wiphy_register+0x1330/0x1d20 net/wireless/core.c:808
ieee80211_register_hw+0x10d1/0x2d40 net/mac80211/main.c:1055
mac80211_hwsim_new_radio+0x192d/0x27e0 drivers/net/wireless/mac80211_hwsim.c:2705
hwsim_new_radio_nl+0x3b4/0x5de drivers/net/wireless/mac80211_hwsim.c:3164
genl_family_rcv_msg+0x57c/0xb30 net/netlink/genetlink.c:600
genl_rcv_msg+0xaf/0x140 net/netlink/genetlink.c:625
netlink_rcv_skb+0x127/0x370 net/netlink/af_netlink.c:2433
genl_rcv+0x24/0x40 net/netlink/genetlink.c:636
netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
netlink_unicast+0x437/0x620 net/netlink/af_netlink.c:1313
netlink_sendmsg+0x733/0xbe0 net/netlink/af_netlink.c:1878
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xc5/0x100 net/socket.c:656
___sys_sendmsg+0x70a/0x840 net/socket.c:2062
__sys_sendmsg+0xa3/0x120 net/socket.c:2096
SYSC_sendmsg net/socket.c:2107 [inline]
SyS_sendmsg+0x27/0x40 net/socket.c:2103
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007f6f64de2c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f6f64de36d4 RCX: 000000000045c849
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000009f5 R14: 00000000004ccac9 R15: 000000000076bf0c
INFO: task syz-executor.0:10975 blocked for more than 140 seconds.
Not tainted 4.14.174-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0 D29120 10975 7553 0x00000004
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
genl_lock net/netlink/genetlink.c:33 [inline]
genl_rcv_msg+0x112/0x140 net/netlink/genetlink.c:623
netlink_rcv_skb+0x127/0x370 net/netlink/af_netlink.c:2433
genl_rcv+0x24/0x40 net/netlink/genetlink.c:636
netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
netlink_unicast+0x437/0x620 net/netlink/af_netlink.c:1313
netlink_sendmsg+0x733/0xbe0 net/netlink/af_netlink.c:1878
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xc5/0x100 net/socket.c:656
___sys_sendmsg+0x70a/0x840 net/socket.c:2062
__sys_sendmsg+0xa3/0x120 net/socket.c:2096
SYSC_sendmsg net/socket.c:2107 [inline]
SyS_sendmsg+0x27/0x40 net/socket.c:2103
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007f6f64d7fc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f6f64d806d4 RCX: 000000000045c849
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 000000000076c0e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000009f5 R14: 00000000004ccac9 R15: 000000000076c0ec
INFO: task syz-executor.2:11009 blocked for more than 140 seconds.
Not tainted 4.14.174-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2 D28688 11009 1 0x00000004
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
rtnl_lock net/core/rtnetlink.c:72 [inline]
rtnetlink_rcv_msg+0x31d/0xb10 net/core/rtnetlink.c:4310
netlink_rcv_skb+0x127/0x370 net/netlink/af_netlink.c:2433
netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
netlink_unicast+0x437/0x620 net/netlink/af_netlink.c:1313
netlink_sendmsg+0x733/0xbe0 net/netlink/af_netlink.c:1878
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xc5/0x100 net/socket.c:656
SYSC_sendto+0x1c4/0x2b0 net/socket.c:1763
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x416543
RSP: 002b:00007ffc11b166c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000c82200 RCX: 0000000000416543
RDX: 0000000000000028 RSI: 0000000000c82250 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffc11b166d0 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000c82250 R15: 0000000000000003

Showing all locks held in the system:
1 lock held by khungtaskd/1057:
#0: (tasklist_lock){.+.+}, at: [<ffffffff81465b93>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4544
4 locks held by kworker/u4:5/2371:
#0: ("%s""netns"){+.+.}, at: [<ffffffff813b67d7>] work_static include/linux/workqueue.h:199 [inline]
#0: ("%s""netns"){+.+.}, at: [<ffffffff813b67d7>] set_work_data kernel/workqueue.c:619 [inline]
#0: ("%s""netns"){+.+.}, at: [<ffffffff813b67d7>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("%s""netns"){+.+.}, at: [<ffffffff813b67d7>] process_one_work+0x727/0x1540 kernel/workqueue.c:2087
#1: (net_cleanup_work){+.+.}, at: [<ffffffff813b6811>] process_one_work+0x761/0x1540 kernel/workqueue.c:2091
#2: (net_mutex){+.+.}, at: [<ffffffff84fc6233>] cleanup_net+0x123/0x820 net/core/net_namespace.c:450
#3: (rtnl_mutex){+.+.}, at: [<ffffffff8585d7f0>] ip6gre_exit_net+0x70/0x580 net/ipv6/ip6_gre.c:1206
3 locks held by kworker/0:2/2747:
#0: ("events"){+.+.}, at: [<ffffffff813b67d7>] work_static include/linux/workqueue.h:199 [inline]
#0: ("events"){+.+.}, at: [<ffffffff813b67d7>] set_work_data kernel/workqueue.c:619 [inline]
#0: ("events"){+.+.}, at: [<ffffffff813b67d7>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("events"){+.+.}, at: [<ffffffff813b67d7>] process_one_work+0x727/0x1540 kernel/workqueue.c:2087
#1: (deferred_process_work){+.+.}, at: [<ffffffff813b6811>] process_one_work+0x761/0x1540 kernel/workqueue.c:2091
#2: (rtnl_mutex){+.+.}, at: [<ffffffff8638835a>] switchdev_deferred_process_work+0xa/0x20 net/switchdev/switchdev.c:150
3 locks held by kworker/1:2/3335:
#0: ("%s"("ipv6_addrconf")){+.+.}, at: [<ffffffff813b67d7>] work_static include/linux/workqueue.h:199 [inline]
#0: ("%s"("ipv6_addrconf")){+.+.}, at: [<ffffffff813b67d7>] set_work_data kernel/workqueue.c:619 [inline]
#0: ("%s"("ipv6_addrconf")){+.+.}, at: [<ffffffff813b67d7>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("%s"("ipv6_addrconf")){+.+.}, at: [<ffffffff813b67d7>] process_one_work+0x727/0x1540 kernel/workqueue.c:2087
#1: ((&(&ifa->dad_work)->work)){+.+.}, at: [<ffffffff813b6811>] process_one_work+0x761/0x1540 kernel/workqueue.c:2091
#2: (rtnl_mutex){+.+.}, at: [<ffffffff8571be80>] addrconf_dad_work+0x90/0xfc0 net/ipv6/addrconf.c:3913
1 lock held by rsyslogd/7383:
#0: (&f->f_pos_lock){+.+.}, at: [<ffffffff8191b786>] __fdget_pos+0xa6/0xc0 fs/file.c:769
2 locks held by getty/7505:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff833adad2>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff833a1714>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7506:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff833adad2>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff833a1714>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7507:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff833adad2>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff833a1714>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7508:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff833adad2>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff833a1714>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7509:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff833adad2>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff833a1714>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7510:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff833adad2>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff833a1714>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
2 locks held by getty/7511:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff833adad2>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff833a1714>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
3 locks held by kworker/0:4/7605:
#0: ("%s"("ipv6_addrconf")){+.+.}, at: [<ffffffff813b67d7>] work_static include/linux/workqueue.h:199 [inline]
#0: ("%s"("ipv6_addrconf")){+.+.}, at: [<ffffffff813b67d7>] set_work_data kernel/workqueue.c:619 [inline]
#0: ("%s"("ipv6_addrconf")){+.+.}, at: [<ffffffff813b67d7>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("%s"("ipv6_addrconf")){+.+.}, at: [<ffffffff813b67d7>] process_one_work+0x727/0x1540 kernel/workqueue.c:2087
#1: ((addr_chk_work).work){+.+.}, at: [<ffffffff813b6811>] process_one_work+0x761/0x1540 kernel/workqueue.c:2091
#2: (rtnl_mutex){+.+.}, at: [<ffffffff85719cba>] addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4408
1 lock held by syz-executor.0/8765:
#0: (rtnl_mutex){+.+.}, at: [<ffffffff83da2a14>] tun_detach drivers/net/tun.c:585 [inline]
#0: (rtnl_mutex){+.+.}, at: [<ffffffff83da2a14>] tun_chr_close+0x34/0x60 drivers/net/tun.c:2671
2 locks held by syz-executor.5/8857:
#0: (&sb->s_type->i_mutex_key#11){+.+.}, at: [<ffffffff84f71e16>] inode_lock include/linux/fs.h:718 [inline]
#0: (&sb->s_type->i_mutex_key#11){+.+.}, at: [<ffffffff84f71e16>] __sock_release+0x86/0x2b0 net/socket.c:601
#1: (rtnl_mutex){+.+.}, at: [<ffffffff857d01ba>] ip6mr_sk_done+0x3a/0x230 net/ipv6/ip6mr.c:1623
1 lock held by syz-executor.4/10949:
#0: (rtnl_mutex){+.+.}, at: [<ffffffff8502970d>] rtnl_lock net/core/rtnetlink.c:72 [inline]
#0: (rtnl_mutex){+.+.}, at: [<ffffffff8502970d>] rtnetlink_rcv_msg+0x31d/0xb10 net/core/rtnetlink.c:4310
1 lock held by syz-executor.5/10952:
#0: (rtnl_mutex){+.+.}, at: [<ffffffff8505374c>] dev_ioctl+0x27c/0xcb0 net/core/dev_ioctl.c:421
2 locks held by syz-executor.5/10981:
#0: (cb_lock){++++}, at: [<ffffffff851e10d5>] genl_rcv+0x15/0x40 net/netlink/genetlink.c:635
#1: (genl_mutex){+.+.}, at: [<ffffffff851e4642>] genl_lock net/netlink/genetlink.c:33 [inline]
#1: (genl_mutex){+.+.}, at: [<ffffffff851e4642>] genl_rcv_msg+0x112/0x140 net/netlink/genetlink.c:623
3 locks held by syz-executor.0/10964:
#0: (cb_lock){++++}, at: [<ffffffff851e10d5>] genl_rcv+0x15/0x40 net/netlink/genetlink.c:635
#1: (genl_mutex){+.+.}, at: [<ffffffff851e4642>] genl_lock net/netlink/genetlink.c:33 [inline]
#1: (genl_mutex){+.+.}, at: [<ffffffff851e4642>] genl_rcv_msg+0x112/0x140 net/netlink/genetlink.c:623
#2: (rtnl_mutex){+.+.}, at: [<ffffffff85d91ea0>] wiphy_register+0x1330/0x1d20 net/wireless/core.c:808
2 locks held by syz-executor.0/10975:
#0: (cb_lock){++++}, at: [<ffffffff851e10d5>] genl_rcv+0x15/0x40 net/netlink/genetlink.c:635
#1: (genl_mutex){+.+.}, at: [<ffffffff851e4642>] genl_lock net/netlink/genetlink.c:33 [inline]
#1: (genl_mutex){+.+.}, at: [<ffffffff851e4642>] genl_rcv_msg+0x112/0x140 net/netlink/genetlink.c:623
1 lock held by syz-executor.2/11009:
#0: (rtnl_mutex){+.+.}, at: [<ffffffff8502970d>] rtnl_lock net/core/rtnetlink.c:72 [inline]
#0: (rtnl_mutex){+.+.}, at: [<ffffffff8502970d>] rtnetlink_rcv_msg+0x31d/0xb10 net/core/rtnetlink.c:4310

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

NMI backtrace for cpu 0
CPU: 0 PID: 1057 Comm: khungtaskd Not tainted 4.14.174-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x13e/0x194 lib/dump_stack.c:58
nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x139/0x17e lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
watchdog+0x5e2/0xb80 kernel/hung_task.c:274
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff864064de


---
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Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.