INFO: task can't die in irqentry_exit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    b36c9697 Add linux-next specific files for 20200828
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=118ca625900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5e3cf99580b5542c
dashboard link: https://syzkaller.appspot.com/bug?extid=c4af95386364bc59b13e
compiler:       gcc (GCC) 10.1.0-syz 20200507

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+c4af95386364bc59b13e@xxxxxxxxxxxxxxxxxxxxxxxxx

INFO: task syz-executor.0:5956 can't die for more than 143 seconds.
task:syz-executor.0  state:R  running task     stack:25424 pid: 5956 ppid: 14284 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:3778 [inline]
 __schedule+0x8e5/0x21e0 kernel/sched/core.c:4527
 preempt_schedule_irq+0xb0/0x150 kernel/sched/core.c:4785
 irqentry_exit_cond_resched kernel/entry/common.c:333 [inline]
 irqentry_exit_cond_resched kernel/entry/common.c:325 [inline]
 irqentry_exit+0x65/0x90 kernel/entry/common.c:363
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:581
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:653 [inline]
RIP: 0010:lock_acquire+0x27b/0xad0 kernel/locking/lockdep.c:5008
Code: 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 f8 06 00 00 48 83 3d 6a d1 5b 08 00 0f 84 a6 05 00 00 48 8b 7c 24 08 57 9d <0f> 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 48 03 44 24 10 48 c7
RSP: 0018:ffffc900088477c0 EFLAGS: 00000286
RAX: 1ffffffff136c7d9 RBX: ffff88808766c200 RCX: 000000005603e267
RDX: dffffc0000000000 RSI: 0000000000000001 RDI: 0000000000000286
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8c6a59e7
R10: fffffbfff18d4b3c R11: 0000000000000001 R12: 0000000000000002
R13: ffffffff89c67640 R14: 0000000000000000 R15: ffff88808766c200
 rcu_lock_acquire include/linux/rcupdate.h:248 [inline]
 rcu_read_lock include/linux/rcupdate.h:641 [inline]
 inet_twsk_purge+0x112/0x7c0 net/ipv4/inet_timewait_sock.c:268
 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:189
 setup_net+0x508/0x850 net/core/net_namespace.c:364
 copy_net_ns+0x31e/0x760 net/core/net_namespace.c:482
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 copy_namespaces+0x385/0x470 kernel/nsproxy.c:179
 copy_process+0x293d/0x6bf0 kernel/fork.c:2090
 _do_fork+0xe8/0xb10 kernel/fork.c:2448
 __do_sys_clone+0xc8/0x110 kernel/fork.c:2565
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45d5b9
Code: Bad RIP value.
RSP: 002b:00007fda8e0a3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000001f40 RCX: 000000000045d5b9
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 00000000e1004d7c
RBP: 000000000118cf90 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffe7d457dcf R14: 00007fda8e0a49c0 R15: 000000000118cf4c

Showing all locks held in the system:
1 lock held by khungtaskd/1169:
 #0: ffffffff89c67640 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5825
1 lock held by in:imklog/6579:
 #0: ffff8880a166e430 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930
3 locks held by kworker/u4:2/15395:
1 lock held by syz-executor.0/5956:
3 locks held by syz-executor.1/12814:
 #0: ffff8880ae635f98 (&rq->lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1292 [inline]
 #0: ffff8880ae635f98 (&rq->lock){-.-.}-{2:2}, at: __schedule+0x232/0x21e0 kernel/sched/core.c:4445
 #1: ffff8880ae620ec8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2fb/0x400 kernel/sched/psi.c:833
 #2: ffff888090a82438 (&sig->wait_chldexit){....}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:122

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