INFO: task hung in nbd_ioctl (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 4c5bf01e Linux 4.14.161
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=142459c1e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=2f880a3dbba6d2e2
dashboard link: https://syzkaller.appspot.com/bug?extid=2955441f38a151da301f
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1261b98ee00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=155c1059e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+295544...@syzkaller.appspotmail.com

block nbd2: shutting down sockets
block nbd5: shutting down sockets
block nbd3: shutting down sockets
block nbd4: shutting down sockets
block nbd0: shutting down sockets
INFO: task syz-executor099:7227 blocked for more than 140 seconds.
Not tainted 4.14.161-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor099 D29008 7227 7223 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_timeout+0x93b/0xe10 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 kernel/sched/completion.c:123 [inline]
wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144
flush_workqueue+0x3d1/0x1400 kernel/workqueue.c:2674
nbd_start_device_ioctl drivers/block/nbd.c:1239 [inline]
__nbd_ioctl drivers/block/nbd.c:1310 [inline]
nbd_ioctl+0x545/0xb30 drivers/block/nbd.c:1350
__blkdev_driver_ioctl block/ioctl.c:297 [inline]
blkdev_ioctl+0x96b/0x1860 block/ioctl.c:594
block_ioctl+0xde/0x120 fs/block_dev.c:1881
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x44a719
RSP: 002b:00007f34a8646ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 000000000044a719
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000006
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00007fff3033079f R14: 00007f34a86479c0 R15: 0000000000000000
INFO: task syz-executor099:7228 blocked for more than 140 seconds.
Not tainted 4.14.161-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor099 D28432 7228 7221 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_timeout+0x93b/0xe10 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 kernel/sched/completion.c:123 [inline]
wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144
flush_workqueue+0x3d1/0x1400 kernel/workqueue.c:2674
nbd_start_device_ioctl drivers/block/nbd.c:1239 [inline]
__nbd_ioctl drivers/block/nbd.c:1310 [inline]
nbd_ioctl+0x545/0xb30 drivers/block/nbd.c:1350
__blkdev_driver_ioctl block/ioctl.c:297 [inline]
blkdev_ioctl+0x96b/0x1860 block/ioctl.c:594
block_ioctl+0xde/0x120 fs/block_dev.c:1881
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x44a719
RSP: 002b:00007f34a8646ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 000000000044a719
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000006
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00007fff3033079f R14: 00007f34a86479c0 R15: 0000000000000000
INFO: task syz-executor099:7229 blocked for more than 140 seconds.
Not tainted 4.14.161-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor099 D28016 7229 7219 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_timeout+0x93b/0xe10 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 kernel/sched/completion.c:123 [inline]
wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144
flush_workqueue+0x3d1/0x1400 kernel/workqueue.c:2674
nbd_start_device_ioctl drivers/block/nbd.c:1239 [inline]
__nbd_ioctl drivers/block/nbd.c:1310 [inline]
nbd_ioctl+0x545/0xb30 drivers/block/nbd.c:1350
__blkdev_driver_ioctl block/ioctl.c:297 [inline]
blkdev_ioctl+0x96b/0x1860 block/ioctl.c:594
block_ioctl+0xde/0x120 fs/block_dev.c:1881
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x44a719
RSP: 002b:00007f34a8646ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 000000000044a719
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000006
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00007fff3033079f R14: 00007f34a86479c0 R15: 0000000000000000
INFO: task syz-executor099:7235 blocked for more than 140 seconds.
Not tainted 4.14.161-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor099 D29008 7235 7222 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_timeout+0x93b/0xe10 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 kernel/sched/completion.c:123 [inline]
wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144
flush_workqueue+0x3d1/0x1400 kernel/workqueue.c:2674
nbd_start_device_ioctl drivers/block/nbd.c:1239 [inline]
__nbd_ioctl drivers/block/nbd.c:1310 [inline]
nbd_ioctl+0x545/0xb30 drivers/block/nbd.c:1350
__blkdev_driver_ioctl block/ioctl.c:297 [inline]
blkdev_ioctl+0x96b/0x1860 block/ioctl.c:594
block_ioctl+0xde/0x120 fs/block_dev.c:1881
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x44a719
RSP: 002b:00007f34a8646ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 000000000044a719
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000006
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00007fff3033079f R14: 00007f34a86479c0 R15: 0000000000000000
INFO: task syz-executor099:7236 blocked for more than 140 seconds.
Not tainted 4.14.161-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor099 D28744 7236 7220 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_timeout+0x93b/0xe10 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 kernel/sched/completion.c:123 [inline]
wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144
flush_workqueue+0x3d1/0x1400 kernel/workqueue.c:2674
nbd_start_device_ioctl drivers/block/nbd.c:1239 [inline]
__nbd_ioctl drivers/block/nbd.c:1310 [inline]
nbd_ioctl+0x545/0xb30 drivers/block/nbd.c:1350
__blkdev_driver_ioctl block/ioctl.c:297 [inline]
blkdev_ioctl+0x96b/0x1860 block/ioctl.c:594
block_ioctl+0xde/0x120 fs/block_dev.c:1881
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x44a719
RSP: 002b:00007f34a8646ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 000000000044a719
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000006
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00007fff3033079f R14: 00007f34a86479c0 R15: 0000000000000000
INFO: task syz-executor099:7239 blocked for more than 140 seconds.
Not tainted 4.14.161-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor099 D29008 7239 7218 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_timeout+0x93b/0xe10 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 kernel/sched/completion.c:123 [inline]
wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144
flush_workqueue+0x3d1/0x1400 kernel/workqueue.c:2674
nbd_start_device_ioctl drivers/block/nbd.c:1239 [inline]
__nbd_ioctl drivers/block/nbd.c:1310 [inline]
nbd_ioctl+0x545/0xb30 drivers/block/nbd.c:1350
__blkdev_driver_ioctl block/ioctl.c:297 [inline]
blkdev_ioctl+0x96b/0x1860 block/ioctl.c:594
block_ioctl+0xde/0x120 fs/block_dev.c:1881
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x44a719
RSP: 002b:00007f34a8646ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 000000000044a719
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000006
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00007fff3033079f R14: 00007f34a86479c0 R15: 0000000000000000

Showing all locks held in the system:
1 lock held by khungtaskd/1045:
#0: (tasklist_lock){.+.+}, at: [<ffffffff8148c8d8>]
debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544
2 locks held by kworker/u5:0/1179:
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>] work_static
include/linux/workqueue.h:199 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_data kernel/workqueue.c:619 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
process_one_work+0x76e/0x1600 kernel/workqueue.c:2085
#1: ((&args->work)){+.+.}, at: [<ffffffff813d585b>]
process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089
1 lock held by rsyslogd/7070:
#0: (&f->f_pos_lock){+.+.}, at: [<ffffffff81966a5b>]
__fdget_pos+0xab/0xd0 fs/file.c:769
2 locks held by getty/7193:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff86650bc3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83492216>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7194:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff86650bc3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83492216>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7195:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff86650bc3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83492216>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7196:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff86650bc3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83492216>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7197:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff86650bc3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83492216>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7198:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff86650bc3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83492216>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7199:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff86650bc3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83492216>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by kworker/u5:1/7246:
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>] work_static
include/linux/workqueue.h:199 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_data kernel/workqueue.c:619 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
process_one_work+0x76e/0x1600 kernel/workqueue.c:2085
#1: ((&args->work)){+.+.}, at: [<ffffffff813d585b>]
process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089
2 locks held by kworker/u5:2/7249:
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>] work_static
include/linux/workqueue.h:199 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_data kernel/workqueue.c:619 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
process_one_work+0x76e/0x1600 kernel/workqueue.c:2085
#1: ((&args->work)){+.+.}, at: [<ffffffff813d585b>]
process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089
2 locks held by kworker/u5:3/7250:
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>] work_static
include/linux/workqueue.h:199 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_data kernel/workqueue.c:619 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
process_one_work+0x76e/0x1600 kernel/workqueue.c:2085
#1: ((&args->work)){+.+.}, at: [<ffffffff813d585b>]
process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089
2 locks held by kworker/u5:4/7251:
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>] work_static
include/linux/workqueue.h:199 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_data kernel/workqueue.c:619 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
process_one_work+0x76e/0x1600 kernel/workqueue.c:2085
#1: ((&args->work)){+.+.}, at: [<ffffffff813d585b>]
process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089
2 locks held by kworker/u5:5/7252:
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>] work_static
include/linux/workqueue.h:199 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_data kernel/workqueue.c:619 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813d581e>]
process_one_work+0x76e/0x1600 kernel/workqueue.c:2085
#1: ((&args->work)){+.+.}, at: [<ffffffff813d585b>]
process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089

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

NMI backtrace for cpu 0
CPU: 0 PID: 1045 Comm: khungtaskd Not tainted 4.14.161-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+0x142/0x197 lib/dump_stack.c:58
nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x141/0x189 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
watchdog+0x5e7/0xb90 kernel/hung_task.c:274
kthread+0x319/0x430 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 0xffffffff866516ae


---
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[syzbot]

syzbot suspects this issue was fixed by commit:

commit 7241d653bcc17eaf4ccb9994f360168d8bfea32d
Author: Tetsuo Handa <penguin...@I-love.SAKURA.ne.jp>
Date: Sat Sep 5 06:14:47 2020 +0000

tipc: fix shutdown() of connection oriented socket

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=152d3ac0500000
start commit: 4c5bf01e Linux 4.14.161
git tree: linux-4.14.y

kernel config: https://syzkaller.appspot.com/x/.config?x=2f880a3dbba6d2e2
dashboard link: https://syzkaller.appspot.com/bug?extid=2955441f38a151da301f

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1261b98ee00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=155c1059e00000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: tipc: fix shutdown() of connection oriented socket

For information about bisection process see: https://goo.gl/tpsmEJ#bisection