INFO: task can't die in cangw_pernet_exit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 14240d4c Add linux-next specific files for 20201210
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16241937500000
kernel config: https://syzkaller.appspot.com/x/.config?x=6dbe20fdaa5aaebe
dashboard link: https://syzkaller.appspot.com/bug?extid=73da79d708b2241c830f
compiler: gcc (GCC) 10.1.0-syz 20200507
CC: [da...@davemloft.net ku...@kernel.org linu...@vger.kernel.org linux-...@vger.kernel.org m...@pengutronix.de net...@vger.kernel.org sock...@hartkopp.net]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+73da79...@syzkaller.appspotmail.com

INFO: task syz-executor.4:11599 can't die for more than 143 seconds.
task:syz-executor.4 state:D stack:25224 pid:11599 ppid: 8515 flags:0x00004006
Call Trace:
context_switch kernel/sched/core.c:4325 [inline]
__schedule+0x8eb/0x21b0 kernel/sched/core.c:5076
schedule+0xcf/0x270 kernel/sched/core.c:5155
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:5214
__mutex_lock_common kernel/locking/mutex.c:1033 [inline]
__mutex_lock+0x81a/0x1110 kernel/locking/mutex.c:1103
cangw_pernet_exit+0xe/0x20 net/can/gw.c:1241
ops_exit_list+0xb0/0x160 net/core/net_namespace.c:187
setup_net+0x508/0x850 net/core/net_namespace.c:365
copy_net_ns+0x376/0x7b0 net/core/net_namespace.c:483
create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
copy_namespaces+0x3e5/0x4d0 kernel/nsproxy.c:179
copy_process+0x2aa7/0x6fe0 kernel/fork.c:2103
kernel_clone+0xe7/0xad0 kernel/fork.c:2465
__do_sys_clone+0xc8/0x110 kernel/fork.c:2582
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45e159
RSP: 002b:00007fc72f273c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000045e159
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 00000000e1004d7c
RBP: 000000000119bfd0 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bf8c
R13: 00007fff3ef04faf R14: 00007fc72f2749c0 R15: 000000000119bf8c

Showing all locks held in the system:
3 locks held by kworker/0:0/5:
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x871/0x1630 kernel/workqueue.c:2246
#1: ffffc90000ca7da8 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1630 kernel/workqueue.c:2250
#2: ffffffff8d0d76e8 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xa/0x20 net/switchdev/switchdev.c:74
3 locks held by kworker/u4:0/9:
4 locks held by kworker/u4:4/1053:
1 lock held by khungtaskd/1659:
#0: ffffffff8b78f120 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x28c kernel/locking/lockdep.c:6254
1 lock held by khugepaged/1670:
1 lock held by in:imklog/8185:
#0: ffff888012dd2d70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:923
3 locks held by kworker/0:3/8473:
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
#0: ffff888010862d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x871/0x1630 kernel/workqueue.c:2246
#1: ffffc9000162fda8 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1630 kernel/workqueue.c:2250
#2: ffffffff8d0d76e8 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xb/0x60 net/core/link_watch.c:250
1 lock held by syz-fuzzer/8480:
#0: ffff888012a06b58 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
#0: ffff888012a06b58 (&mm->mmap_lock#2){++++}-{3:3}, at: do_user_addr_fault+0x93e/0xc60 arch/x86/mm/fault.c:1349
2 locks held by syz-executor.4/11599:
#0: ffffffff8d0bcb50 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x352/0x7b0 net/core/net_namespace.c:479
#1: ffffffff8d0d76e8 (rtnl_mutex){+.+.}-{3:3}, at: cangw_pernet_exit+0xe/0x20 net/can/gw.c:1241
2 locks held by syz-executor.3/12411:
#0: ffffffff8d0bcb50 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x352/0x7b0 net/core/net_namespace.c:479
#1: ffffffff8d0d76e8 (rtnl_mutex){+.+.}-{3:3}, at: cangw_pernet_exit+0xe/0x20 net/can/gw.c:1241
2 locks held by syz-executor.1/12465:
2 locks held by syz-executor.2/12477:

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[syzbot]

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