[syzbot] [usb?] INFO: task hung in usblp_disconnect

syzbot
2024-10-02T01:12:29Z

Hello,

syzbot found the following issue on:

HEAD commit: 075dbe9f6e3c Merge tag 'soc-ep93xx-dt-6.12' of git://git.k..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
console output: https://syzkaller.appspot.com/x/log.txt?x=173846a9980000
kernel config: https://syzkaller.appspot.com/x/.config?x=3d9e1c0225f14ccc
dashboard link: https://syzkaller.appspot.com/bug?extid=5bb5aaead384a4a22890
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103af59f980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/47c253223330/disk-075dbe9f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f66e6e6c457a/vmlinux-075dbe9f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3580fe941737/bzImage-075dbe9f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5bb5aaead384a4a22890@syzkaller.appspotmail.com

INFO: task kworker/0:1:9 blocked for more than 143 seconds.
Not tainted 6.11.0-syzkaller-11558-g075dbe9f6e3c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:1 state:D stack:23904 pid:9 tgid:9 ppid:2 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5315 [inline]
__schedule+0x105f/0x34b0 kernel/sched/core.c:6675
__schedule_loop kernel/sched/core.c:6752 [inline]
schedule+0xe7/0x350 kernel/sched/core.c:6767
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6824
__mutex_lock_common kernel/locking/mutex.c:684 [inline]
__mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752
usblp_disconnect+0x97/0x330 drivers/usb/class/usblp.c:1403
usb_unbind_interface+0x1e8/0x970 drivers/usb/core/driver.c:461
device_remove drivers/base/dd.c:569 [inline]
device_remove+0x122/0x170 drivers/base/dd.c:561
__device_release_driver drivers/base/dd.c:1273 [inline]
device_release_driver_internal+0x44a/0x610 drivers/base/dd.c:1296
bus_remove_device+0x22f/0x420 drivers/base/bus.c:574
device_del+0x396/0x9f0 drivers/base/core.c:3871
usb_disable_device+0x36c/0x7f0 drivers/usb/core/message.c:1418
usb_disconnect+0x2e1/0x920 drivers/usb/core/hub.c:2304
hub_port_connect drivers/usb/core/hub.c:5361 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5661 [inline]
port_event drivers/usb/core/hub.c:5821 [inline]
hub_event+0x1bed/0x4f40 drivers/usb/core/hub.c:5903
process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229
process_scheduled_works kernel/workqueue.c:3310 [inline]
worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
INFO: task kworker/1:0:24 blocked for more than 143 seconds.
Not tainted 6.11.0-syzkaller-11558-g075dbe9f6e3c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:0 state:D stack:23616 pid:24 tgid:24 ppid:2 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5315 [inline]
__schedule+0x105f/0x34b0 kernel/sched/core.c:6675
__schedule_loop kernel/sched/core.c:6752 [inline]
schedule+0xe7/0x350 kernel/sched/core.c:6767
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6824
__mutex_lock_common kernel/locking/mutex.c:684 [inline]
__mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752
usblp_disconnect+0xa1/0x330 drivers/usb/class/usblp.c:1404
usb_unbind_interface+0x1e8/0x970 drivers/usb/core/driver.c:461
device_remove drivers/base/dd.c:569 [inline]
device_remove+0x122/0x170 drivers/base/dd.c:561
__device_release_driver drivers/base/dd.c:1273 [inline]
device_release_driver_internal+0x44a/0x610 drivers/base/dd.c:1296
bus_remove_device+0x22f/0x420 drivers/base/bus.c:574
device_del+0x396/0x9f0 drivers/base/core.c:3871
usb_disable_device+0x36c/0x7f0 drivers/usb/core/message.c:1418
usb_disconnect+0x2e1/0x920 drivers/usb/core/hub.c:2304
hub_port_connect drivers/usb/core/hub.c:5361 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5661 [inline]
port_event drivers/usb/core/hub.c:5821 [inline]
hub_event+0x1bed/0x4f40 drivers/usb/core/hub.c:5903
process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229
process_scheduled_works kernel/workqueue.c:3310 [inline]
worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
INFO: task kworker/0:2:801 blocked for more than 143 seconds.
Not tainted 6.11.0-syzkaller-11558-g075dbe9f6e3c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:2 state:D stack:23728 pid:801 tgid:801 ppid:2 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5315 [inline]
__schedule+0x105f/0x34b0 kernel/sched/core.c:6675
__schedule_loop kernel/sched/core.c:6752 [inline]
schedule+0xe7/0x350 kernel/sched/core.c:6767
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6824
rwsem_down_write_slowpath+0x539/0x12a0 kernel/locking/rwsem.c:1178
__down_write_common kernel/locking/rwsem.c:1306 [inline]
__down_write kernel/locking/rwsem.c:1315 [inline]
down_write+0x1d8/0x200 kernel/locking/rwsem.c:1580
usb_deregister_dev+0x7c/0x1e0 drivers/usb/core/file.c:186
usblp_disconnect+0x4a/0x330 drivers/usb/class/usblp.c:1396
usb_unbind_interface+0x1e8/0x970 drivers/usb/core/driver.c:461
device_remove drivers/base/dd.c:569 [inline]
device_remove+0x122/0x170 drivers/base/dd.c:561
__device_release_driver drivers/base/dd.c:1273 [inline]
device_release_driver_internal+0x44a/0x610 drivers/base/dd.c:1296
bus_remove_device+0x22f/0x420 drivers/base/bus.c:574
device_del+0x396/0x9f0 drivers/base/core.c:3871
usb_disable_device+0x36c/0x7f0 drivers/usb/core/message.c:1418
usb_disconnect+0x2e1/0x920 drivers/usb/core/hub.c:2304
hub_port_connect drivers/usb/core/hub.c:5361 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5661 [inline]
port_event drivers/usb/core/hub.c:5821 [inline]
hub_event+0x1bed/0x4f40 drivers/usb/core/hub.c:5903
process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229
process_scheduled_works kernel/workqueue.c:3310 [inline]
worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
INFO: task syz.3.56:5781 blocked for more than 144 seconds.
Not tainted 6.11.0-syzkaller-11558-g075dbe9f6e3c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.56 state:D stack:25824 pid:5781 tgid:5781 ppid:3235 flags:0x00000004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5315 [inline]
__schedule+0x105f/0x34b0 kernel/sched/core.c:6675
__schedule_loop kernel/sched/core.c:6752 [inline]
schedule+0xe7/0x350 kernel/sched/core.c:6767
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6824
__mutex_lock_common kernel/locking/mutex.c:684 [inline]
__mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752
usblp_release+0x79/0x310 drivers/usb/class/usblp.c:480
__fput+0x3f6/0xb60 fs/file_table.c:431
task_work_run+0x14e/0x250 kernel/task_work.c:228
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x24e/0x260 kernel/entry/common.c:218
do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fba41e8dff9
RSP: 002b:00007ffc56758068 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fba42047a80 RCX: 00007fba41e8dff9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fba42047a80 R08: 0000000000000000 R09: 00007ffc5675835f
R10: 000000000003fd6c R11: 0000000000000246 R12: 0000000000075f4f
R13: 00007fba420463b8 R14: 0000000000000003 R15: ffffffffffffffff
</TASK>
INFO: task syz.0.60:5817 blocked for more than 144 seconds.
Not tainted 6.11.0-syzkaller-11558-g075dbe9f6e3c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.60 state:D stack:28256 pid:5817 tgid:5794 ppid:3225 flags:0x00000004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5315 [inline]
__schedule+0x105f/0x34b0 kernel/sched/core.c:6675
__schedule_loop kernel/sched/core.c:6752 [inline]
schedule+0xe7/0x350 kernel/sched/core.c:6767
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6824
__mutex_lock_common kernel/locking/mutex.c:684 [inline]
__mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752
usblp_open+0x5c/0x450 drivers/usb/class/usblp.c:417
usb_open+0x186/0x220 drivers/usb/core/file.c:47
chrdev_open+0x237/0x6a0 fs/char_dev.c:414
do_dentry_open+0x6cb/0x1390 fs/open.c:958
vfs_open+0x82/0x3f0 fs/open.c:1088
do_open fs/namei.c:3774 [inline]
path_openat+0x1e6a/0x2d60 fs/namei.c:3933
do_filp_open+0x1dc/0x430 fs/namei.c:3960
do_sys_openat2+0x17a/0x1e0 fs/open.c:1415
do_sys_open fs/open.c:1430 [inline]
__do_sys_openat fs/open.c:1446 [inline]
__se_sys_openat fs/open.c:1441 [inline]
__x64_sys_openat+0x175/0x210 fs/open.c:1441
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc7d662c990
RSP: 002b:00007fc7d608db70 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fc7d662c990
RDX: 0000000000000002 RSI: 00007fc7d608dc10 RDI: 00000000ffffff9c
RBP: 00007fc7d608dc10 R08: 0000000000000000 R09: 00007fc7d608d987
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fc7d67e6058 R15: 00007ffc3b29f2f8
</TASK>

Showing all locks held in the system:
6 locks held by kworker/0:1/9:
#0: ffff8881066f4d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x129b/0x1ba0 kernel/workqueue.c:3204
#1: ffffc9000009fd80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3205
#2: ffff8881097aa190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#2: ffff8881097aa190 (&dev->mutex){....}-{3:3}, at: hub_event+0x1be/0x4f40 drivers/usb/core/hub.c:5849
#3: ffff888117d82190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#3: ffff888117d82190 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x10a/0x920 drivers/usb/core/hub.c:2295
#4: ffff88811e191160 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#4: ffff88811e191160 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1095 [inline]
#4: ffff88811e191160 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa4/0x610 drivers/base/dd.c:1293
#5: ffffffff89a93548 (usblp_mutex){+.+.}-{3:3}, at: usblp_disconnect+0x97/0x330 drivers/usb/class/usblp.c:1403
7 locks held by kworker/1:0/24:
#0: ffff8881066f4d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x129b/0x1ba0 kernel/workqueue.c:3204
#1: ffffc9000019fd80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3205
#2: ffff888109792190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#2: ffff888109792190 (&dev->mutex){....}-{3:3}, at: hub_event+0x1be/0x4f40 drivers/usb/core/hub.c:5849
#3: ffff88811f337190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#3: ffff88811f337190 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x10a/0x920 drivers/usb/core/hub.c:2295
#4: ffff88811be6e160 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#4: ffff88811be6e160 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1095 [inline]
#4: ffff88811be6e160 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa4/0x610 drivers/base/dd.c:1293
#5: ffffffff89a93548 (usblp_mutex){+.+.}-{3:3}, at: usblp_disconnect+0x97/0x330 drivers/usb/class/usblp.c:1403
#6: ffff888113d99100 (&usblp->mut){+.+.}-{3:3}, at: usblp_disconnect+0xa1/0x330 drivers/usb/class/usblp.c:1404
1 lock held by khungtaskd/30:
#0: ffffffff88ebacc0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
#0: ffffffff88ebacc0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff88ebacc0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x75/0x340 kernel/locking/lockdep.c:6701
6 locks held by kworker/0:2/801:
#0: ffff8881066f4d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x129b/0x1ba0 kernel/workqueue.c:3204
#1: ffffc90001d1fd80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3205
#2: ffff888109bc2190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#2: ffff888109bc2190 (&dev->mutex){....}-{3:3}, at: hub_event+0x1be/0x4f40 drivers/usb/core/hub.c:5849
#3: ffff88811f336190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#3: ffff88811f336190 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x10a/0x920 drivers/usb/core/hub.c:2295
#4: ffff88810a396160 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#4: ffff88810a396160 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1095 [inline]
#4: ffff88810a396160 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa4/0x610 drivers/base/dd.c:1293
#5: ffffffff899da270 (minor_rwsem){++++}-{3:3}, at: usb_deregister_dev+0x7c/0x1e0 drivers/usb/core/file.c:186
2 locks held by getty/2606:
#0: ffff8881092ac0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc900000432f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xfba/0x1480 drivers/tty/n_tty.c:2211
6 locks held by kworker/0:0/2674:
#0: ffff8881066f4d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x129b/0x1ba0 kernel/workqueue.c:3204
#1: ffffc900005bfd80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3205
#2: ffff888109782190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#2: ffff888109782190 (&dev->mutex){....}-{3:3}, at: hub_event+0x1be/0x4f40 drivers/usb/core/hub.c:5849
#3: ffff888109389190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#3: ffff888109389190 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x10a/0x920 drivers/usb/core/hub.c:2295
#4: ffff8881083de160 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#4: ffff8881083de160 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1095 [inline]
#4: ffff8881083de160 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa4/0x610 drivers/base/dd.c:1293
#5: ffffffff899da270 (minor_rwsem){++++}-{3:3}, at: usb_deregister_dev+0x7c/0x1e0 drivers/usb/core/file.c:186
6 locks held by kworker/0:4/5509:
#0: ffff8881066f4d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x129b/0x1ba0 kernel/workqueue.c:3204
#1: ffffc90002bbfd80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3205
#2: ffff888109baa190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#2: ffff888109baa190 (&dev->mutex){....}-{3:3}, at: hub_event+0x1be/0x4f40 drivers/usb/core/hub.c:5849
#3: ffff88810938e190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#3: ffff88810938e190 (&dev->mutex){....}-{3:3}, at: __device_attach+0x7f/0x4b0 drivers/base/dd.c:1005
#4: ffff888109388160 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1014 [inline]
#4: ffff888109388160 (&dev->mutex){....}-{3:3}, at: __device_attach+0x7f/0x4b0 drivers/base/dd.c:1005
#5: ffffffff899da270 (minor_rwsem){++++}-{3:3}, at: usb_register_dev+0x11c/0x550 drivers/usb/core/file.c:134
1 lock held by syz.3.56/5781:
#0: ffffffff89a93548 (usblp_mutex){+.+.}-{3:3}, at: usblp_release+0x79/0x310 drivers/usb/class/usblp.c:480
1 lock held by syz.1.58/5809:
#0: ffff888113d99100 (&usblp->mut){+.+.}-{3:3}, at: usblp_ioctl+0xbb/0xf00 drivers/usb/class/usblp.c:528
2 locks held by syz.0.60/5817:
#0: ffffffff899da270 (minor_rwsem){++++}-{3:3}, at: usb_open+0x23/0x220 drivers/usb/core/file.c:38
#1: ffffffff89a93548 (usblp_mutex){+.+.}-{3:3}, at: usblp_open+0x5c/0x450 drivers/usb/class/usblp.c:417
1 lock held by syz.1.440/8907:
#0: ffffffff88ec6638 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock+0x1a4/0x3b0 kernel/rcu/tree_exp.h:329
1 lock held by syz.1.440/8911:
#0: ffffffff88ec6638 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock+0x282/0x3b0 kernel/rcu/tree_exp.h:297

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.11.0-syzkaller-11558-g075dbe9f6e3c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline]
watchdog+0xf0c/0x1240 kernel/hung_task.c:379
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:111

---
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