INFO: task can't die in connmark_exit_net

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    15ac8fdb Add linux-next specific files for 20201207
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15fbf86b500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3696b8138207d24d
dashboard link: https://syzkaller.appspot.com/bug?extid=b3b63b6bff456bd95294
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13121287500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b3b63b6bff456bd95294@xxxxxxxxxxxxxxxxxxxxxxxxx

INFO: task syz-executor.4:13889 can't die for more than 143 seconds.
task:syz-executor.4  state:D stack:26200 pid:13889 ppid: 12369 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
 tc_action_net_exit include/net/act_api.h:147 [inline]
 connmark_exit_net+0x20/0x130 net/sched/act_connmark.c:241
 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:190
 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: 0033:0x45e0f9
RSP: 002b:00007fd04901bc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000045e0f9
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 00000000e900e57c
RBP: 000000000119c078 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119c034
R13: 00007fff629a5d7f R14: 00007fd04901c9c0 R15: 000000000119c034
INFO: task syz-executor.1:13932 can't die for more than 143 seconds.
task:syz-executor.1  state:D stack:26320 pid:13932 ppid: 12371 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
 tc_action_net_exit include/net/act_api.h:147 [inline]
 gate_exit_net+0x20/0x130 net/sched/act_gate.c:624
 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:190
 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: 0033:0x45e0f9
RSP: 002b:00007fd373ed4c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000045e0f9
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 00000000e900e57c
RBP: 000000000119c120 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119c0dc
R13: 00007ffc4464352f R14: 00007fd373ed59c0 R15: 000000000119c0dc

Showing all locks held in the system:
3 locks held by kworker/0:2/8:
3 locks held by kworker/1:1/35:
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x871/0x1630 kernel/workqueue.c:2246
 #1: ffffc90000e6fda8 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1630 kernel/workqueue.c:2250
 #2: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xa3/0x1280 net/ipv6/addrconf.c:4028
1 lock held by khungtaskd/1655:
 #0: ffffffff8b78db60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x28c kernel/locking/lockdep.c:6254
1 lock held by in:imklog/8192:
 #0: ffff888012b58370 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:923
4 locks held by kworker/u4:1/8580:
3 locks held by kworker/u4:2/8830:
3 locks held by kworker/0:4/9816:
 #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: ffffc90001dd7da8 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1630 kernel/workqueue.c:2250
 #2: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xa/0x20 net/switchdev/switchdev.c:74
3 locks held by kworker/0:6/10010:
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff8881473fb538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x871/0x1630 kernel/workqueue.c:2246
 #1: ffffc9000af5fda8 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1630 kernel/workqueue.c:2250
 #2: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xa3/0x1280 net/ipv6/addrconf.c:4028
3 locks held by kworker/0:27/12319:
 #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: ffffc90002e67da8 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1630 kernel/workqueue.c:2250
 #2: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xb/0x60 net/core/link_watch.c:250
2 locks held by syz-executor.4/13889:
 #0: ffffffff8d0bc590 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x352/0x7b0 net/core/net_namespace.c:479
 #1: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: tc_action_net_exit include/net/act_api.h:147 [inline]
 #1: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: connmark_exit_net+0x20/0x130 net/sched/act_connmark.c:241
2 locks held by syz-executor.1/13932:
 #0: ffffffff8d0bc590 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x352/0x7b0 net/core/net_namespace.c:479
 #1: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: tc_action_net_exit include/net/act_api.h:147 [inline]
 #1: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: gate_exit_net+0x20/0x130 net/sched/act_gate.c:624
2 locks held by syz-executor.3/14181:
 #0: ffffffff8d0bc590 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x352/0x7b0 net/core/net_namespace.c:479
 #1: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: tc_action_net_exit include/net/act_api.h:147 [inline]
 #1: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: gate_exit_net+0x20/0x130 net/sched/act_gate.c:624
2 locks held by syz-executor.5/14278:
1 lock held by syz-executor.0/14352:
 #0: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d0d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x443/0xb80 net/core/rtnetlink.c:5559

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