INFO: task hung in kvm_mmu_pre_destroy_vm (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: c6db52a8 Linux 4.14.183
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15b2bea6100000
kernel config: https://syzkaller.appspot.com/x/.config?x=98bbe4d18401ff4
dashboard link: https://syzkaller.appspot.com/bug?extid=002d71fcec1b9e390755
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+002d71...@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 syz-executor.3:32133 blocked for more than 140 seconds.
Not tainted 4.14.183-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3 D27872 32133 6342 0x00000006
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x8a6/0x1d70 kernel/sched/core.c:3384
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_timeout+0x86c/0xe50 kernel/time/timer.c:1723
do_wait_for_common kernel/sched/completion.c:91 [inline]
__wait_for_common kernel/sched/completion.c:112 [inline]
wait_for_common+0x272/0x430 kernel/sched/completion.c:123
kthread_stop+0xce/0x640 kernel/kthread.c:530
kvm_mmu_pre_destroy_vm+0x41/0x4f arch/x86/kvm/mmu.c:5850
kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:769 [inline]
kvm_put_kvm+0x2ff/0xa90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:806
kvm_vm_release+0x3f/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:817
__fput+0x25f/0x7a0 fs/file_table.c:210
task_work_run+0x113/0x190 kernel/task_work.c:113
get_signal+0x1887/0x1c90 kernel/signal.c:2234
do_signal+0x7c/0x15d0 arch/x86/kernel/signal.c:814
exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45ca69
RSP: 002b:00007f3dd7a09c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: fffffffffffffff2 RBX: 00000000004e7400 RCX: 000000000045ca69
RDX: 0000000000000000 RSI: 000000000000ae41 RDI: 0000000000000007
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000396 R14: 00000000004c6306 R15: 00007f3dd7a0a6d4

Showing all locks held in the system:
1 lock held by khungtaskd/1049:
#0: (tasklist_lock){.+.?}, at: [<ffffffff8146c8d0>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
1 lock held by in:imklog/6036:
#0: (&f->f_pos_lock){+.+.}, at: [<ffffffff8191e426>] __fdget_pos+0xa6/0xc0 fs/file.c:769
2 locks held by agetty/6254:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff833bd862>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff833b8e44>] n_tty_read+0x1e4/0x16e0 drivers/tty/n_tty.c:2156

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

NMI backtrace for cpu 1
CPU: 1 PID: 1049 Comm: khungtaskd Not tainted 4.14.183-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+0x1b2/0x283 lib/dump_stack.c:58
nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x13a/0x17f 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3623 Comm: systemd-journal Not tainted 4.14.183-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880948f8300 task.stack: ffff888094900000
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:get_running_cputimer include/linux/sched/cputime.h:84 [inline]
RIP: 0010:account_group_exec_runtime include/linux/sched/cputime.h:169 [inline]
RIP: 0010:update_curr+0x31c/0x670 kernel/sched/fair.c:857
RSP: 0018:ffff888094907a90 EFLAGS: 00000806
RAX: 0000000000000000 RBX: ffff8880948f8380 RCX: 1ffff1101291f16f
RDX: 1ffff1101291469f RSI: 0000000000000002 RDI: ffff8880948a34f8
RBP: ffff8880aec2b620 R08: 0000000000000001 R09: 0000000000000001
R10: ffff8880948f8bb0 R11: ffff8880948f8300 R12: 00000000004282de
R13: ffff8880948a33c0 R14: ffff8880948a34e0 R15: 0000000000000009
FS: 00007fe7408fe8c0(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe73de96000 CR3: 0000000094f59000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
dequeue_entity+0x24/0x2430 kernel/sched/fair.c:3805
dequeue_task_fair+0x5e/0x1450 kernel/sched/fair.c:4959
__schedule+0x2cc/0x1d70 kernel/sched/core.c:3333
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_hrtimeout_range_clock+0x2ac/0x2f0 kernel/time/hrtimer.c:1707
ep_poll+0x865/0xa50 fs/eventpoll.c:1829
SYSC_epoll_wait fs/eventpoll.c:2203 [inline]
SyS_epoll_wait+0x152/0x1a0 fs/eventpoll.c:2168
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7fe73fbc82e3
RSP: 002b:00007ffdb32d16b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e8
RAX: ffffffffffffffda RBX: 000055c30ecbf200 RCX: 00007fe73fbc82e3
RDX: 0000000000000013 RSI: 00007ffdb32d16c0 RDI: 0000000000000008
RBP: 00007ffdb32d18b0 R08: 00007ffdb334f000 R09: 000000e751405721
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffdb32d16c0
R13: 0000000000000001 R14: ffffffffffffffff R15: 0005a78020304e79
Code: 00 4c 8b ab 80 06 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d bd 38 01 00 00 4d 8d b5 20 01 00 00 48 89 fa 48 c1 ea 03 0f b6 04 02 <48> 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 ef 02 00 00 41 0f b6


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[syzbot]

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