INFO: task kworker/1:1:43 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:1 state:D stack:21672 pid:43 tgid:43 ppid:2 task_flags:0x4288060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
context_switch kernel/sched/core.c:5260 [inline]
__schedule+0xeb0/0x3e50 kernel/sched/core.c:6867
__schedule_loop kernel/sched/core.c:6949 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:6964
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7021
__mutex_lock_common kernel/locking/mutex.c:692 [inline]
__mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776
uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline]
kobject_uevent_net_broadcast lib/kobject_uevent.c:410 [inline]
kobject_uevent_env+0xba8/0x18b0 lib/kobject_uevent.c:608
device_del+0x605/0x9b0 drivers/base/core.c:3896
usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1418
usb_disconnect+0x2e2/0x9a0 drivers/usb/core/hub.c:2345
hub_port_connect drivers/usb/core/hub.c:5407 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
port_event drivers/usb/core/hub.c:5871 [inline]
hub_event+0x1d0c/0x4af0 drivers/usb/core/hub.c:5953
process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
process_scheduled_works kernel/workqueue.c:3340 [inline]
worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
kthread+0x3b3/0x730 kernel/kthread.c:463
ret_from_fork+0x6c3/0xa20 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
INFO: task kworker/1:4:5233 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:4 state:D
stack:22120 pid:5233 tgid:5233 ppid:2 task_flags:0x4288060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
context_switch kernel/sched/core.c:5260 [inline]
__schedule+0xeb0/0x3e50 kernel/sched/core.c:6867
__schedule_loop kernel/sched/core.c:6949 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:6964
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7021
__mutex_lock_common kernel/locking/mutex.c:692 [inline]
__mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776
uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline]
kobject_uevent_net_broadcast lib/kobject_uevent.c:410 [inline]
kobject_uevent_env+0xba8/0x18b0 lib/kobject_uevent.c:608
device_del+0x605/0x9b0 drivers/base/core.c:3896
device_unregister+0x1d/0xe0 drivers/base/core.c:3919
device_destroy+0x99/0xe0 drivers/base/core.c:4473
usb_deregister_dev+0x70/0x210 drivers/usb/core/file.c:184
iowarrior_disconnect+0x4c/0x350 drivers/usb/misc/iowarrior.c:915
usb_unbind_interface+0x1dd/0x9e0 drivers/usb/core/driver.c:458
device_remove drivers/base/dd.c:571 [inline]
device_remove+0x12a/0x180 drivers/base/dd.c:563
__device_release_driver drivers/base/dd.c:1282 [inline]
device_release_driver_internal+0x42e/0x600 drivers/base/dd.c:1305
bus_remove_device+0x22f/0x440 drivers/base/bus.c:616
device_del+0x376/0x9b0 drivers/base/core.c:3878
usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1418
usb_disconnect+0x2e2/0x9a0 drivers/usb/core/hub.c:2345
hub_port_connect drivers/usb/core/hub.c:5407 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
port_event drivers/usb/core/hub.c:5871 [inline]
hub_event+0x1d0c/0x4af0 drivers/usb/core/hub.c:5953
process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
process_scheduled_works kernel/workqueue.c:3340 [inline]
worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
kthread+0x3b3/0x730 kernel/kthread.c:463
ret_from_fork+0x6c3/0xa20 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
INFO: task syz.4.411:6651 blocked for more than 145 seconds.
Not tainted syzkaller #0
Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.411 state:D
stack:27624 pid:6651 tgid:6650 ppid:2973 task_flags:0x40044c flags:0x00080003
Call Trace:
context_switch kernel/sched/core.c:5260 [inline]
__schedule+0xeb0/0x3e50 kernel/sched/core.c:6867
__schedule_loop kernel/sched/core.c:6949 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:6964
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7021
__mutex_lock_common kernel/locking/mutex.c:692 [inline]
__mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776
uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline]
kobject_uevent_net_broadcast lib/kobject_uevent.c:410 [inline]
kobject_uevent_env+0xba8/0x18b0 lib/kobject_uevent.c:608
device_remove+0xcb/0x180 drivers/base/dd.c:569
__device_release_driver drivers/base/dd.c:1282 [inline]
device_release_driver_internal+0x42e/0x600 drivers/base/dd.c:1305
driver_detach+0xd8/0x1b0 drivers/base/dd.c:1368
bus_remove_driver+0x13b/0x2e0 drivers/base/bus.c:784
driver_unregister+0x76/0xb0 drivers/base/driver.c:277
usb_gadget_unregister_driver+0x49/0x70 drivers/usb/gadget/udc/core.c:1751
raw_release+0x19b/0x260 drivers/usb/gadget/legacy/raw_gadget.c:463
__fput+0x3ff/0xb40 fs/file_table.c:468
task_work_run+0x150/0x240 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x829/0x2a30 kernel/exit.c:971
do_group_exit+0xd5/0x2a0 kernel/exit.c:1112
get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
exit_to_user_mode_loop+0x7e/0x430 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x4a8/0x570 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9e2720ab4b
RSP: 002b:00007f9e25c64f50 EFLAGS: 00000246
ORIG_RAX: 0000000000000010
RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 00007f9e2720ab4b
RDX: 00007f9e25c65fe0 RSI: 0000000080085502 RDI: 0000000000000003
RBP: 00007f9e27278c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000200000000340
R13: 00002000000000c0 R14: 00007f9e27485fa0 R15: 00007ffeed8b94b8
Showing all locks held in the system:
5 locks held by kworker/0:0/9:
2 locks held by ksoftirqd/0/14:
1 lock held by khungtaskd/30:
#0:
ffffffff894da3a0
(
rcu_read_lock
){....}-{1:3}
, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
4 locks held by kworker/u8:2/36:
#0:
ffff888100ac4948
(
(wq_completion)netns
){+.+.}-{0:0}
, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
#1:
ffffc90000267ca8
(
net_cleanup_work){+.+.}-{0:0}
, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
#2:
ffffffff8a8b49b0 (
pernet_ops_rwsem
){++++}-{4:4}
, at: cleanup_net+0xab/0x900 net/core/net_namespace.c:670
#3:
ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: ops_exit_rtnl_list net/core/net_namespace.c:173 [inline]
, at: ops_undo_list+0x7ec/0xab0 net/core/net_namespace.c:248
3 locks held by kworker/1:1/43:
5 locks held by kworker/0:2/1122:
3 locks held by kworker/u8:13/1533:
#0:
ffff88811259a948
(
(wq_completion)ipv6_addrconf
){+.+.}-{0:0}
, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
#1:
ffffc900024dfca8
(
(work_completion)(&(&net->ipv6.addr_chk_work)->work)
){+.+.}-{0:0}
, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
#2:
ffffffff8a8ccfe8
(rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4734
2 locks held by getty/2924:
#0:
ffff8881129130a0
(&tty->ldisc_sem
){++++}-{0:0}
, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1:
ffffc900000452f0
(
&ldata->atomic_read_lock){+.+.}-{4:4}
, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211
4 locks held by udevd/5219:
#0:
ffff8881260b59e0
(&p->lock){+.+.}-{4:4}
, at: seq_read_iter+0xe1/0x1270 fs/seq_file.c:182
#1: ffff88811eab8088
(
&of->mutex
#2
){+.+.}-{4:4}
, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:172
#2:
ffff88811dd452d8
(
kn->active
#9
){++++}-{0:0}
, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
, at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:173
#3:
ffff88813a64b198
(
&dev->mutex){....}-{4:4}
, at: device_lock_interruptible include/linux/device.h:900 [inline]
, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
3 locks held by kworker/1:4/5233:
5 locks held by kworker/0:4/5239:
4 locks held by udevd/5394:
#0: ffff88811ed90668
(
&p->lock
){+.+.}-{4:4}
, at: seq_read_iter+0xe1/0x1270 fs/seq_file.c:182
#1: ffff88811d456488
(
&of->mutex
#2
){+.+.}-{4:4}
, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:172
#2:
ffff88810abe8a58 (
kn->active#9
){++++}-{0:0}
, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
, at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:173
#3:
ffff88813a64d198
(
&dev->mutex
){....}-{4:4}
, at: device_lock_interruptible include/linux/device.h:900 [inline]
, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
1 lock held by syz.3.412/6661:
2 locks held by syz-executor/6665:
#0: ffffffff8a8b49b0
(
pernet_ops_rwsem
){++++}-{4:4}
, at: copy_net_ns+0x41e/0x780 net/core/net_namespace.c:577
#1:
ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: register_netdevice_notifier_net+0x23/0xb0 net/core/dev.c:2096
2 locks held by syz-executor/6675:
#0:
ffffffff8a8b49b0
(
pernet_ops_rwsem){++++}-{4:4}
, at: copy_net_ns+0x41e/0x780 net/core/net_namespace.c:577
#1:
ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: register_netdevice_notifier_net+0x23/0xb0 net/core/dev.c:2096
2 locks held by syz-executor/6685:
#0: ffffffff8a8b49b0
(
pernet_ops_rwsem
){++++}-{4:4}
, at: copy_net_ns+0x41e/0x780 net/core/net_namespace.c:577
#1:
ffffffff8a8ccfe8
(
rtnl_mutex){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: register_netdevice_notifier_net+0x23/0xb0 net/core/dev.c:2096
2 locks held by syz-executor/6688:
#0:
ffffffff8a8b49b0
(pernet_ops_rwsem
){++++}-{4:4}
, at: copy_net_ns+0x41e/0x780 net/core/net_namespace.c:577
#1: ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: register_netdevice_notifier_net+0x23/0xb0 net/core/dev.c:2096
2 locks held by syz-executor/6697:
#0:
ffffffff8a8b49b0
(
pernet_ops_rwsem
){++++}-{4:4}
, at: copy_net_ns+0x41e/0x780 net/core/net_namespace.c:577
#1: ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: register_netdevice_notifier_net+0x23/0xb0 net/core/dev.c:2096
2 locks held by syz-executor/6715:
#0: ffffffff8a8b49b0
(
pernet_ops_rwsem
){++++}-{4:4}
, at: copy_net_ns+0x41e/0x780 net/core/net_namespace.c:577
#1:
ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: register_netdevice_notifier_net+0x23/0xb0 net/core/dev.c:2096
2 locks held by syz-executor/6723:
#0:
ffffffff8a8b49b0
(
pernet_ops_rwsem
){++++}-{4:4}
, at: copy_net_ns+0x41e/0x780 net/core/net_namespace.c:577
#1:
ffffffff8a8ccfe8
(rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: register_netdevice_notifier_net+0x23/0xb0 net/core/dev.c:2096
2 locks held by syz-executor/6732:
#0: ffffffff8a8b49b0
(
pernet_ops_rwsem
){++++}-{4:4}
, at: copy_net_ns+0x41e/0x780 net/core/net_namespace.c:577
#1:
ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: register_netdevice_notifier_net+0x23/0xb0 net/core/dev.c:2096
2 locks held by syz-executor/6735:
#0:
ffffffff8a8b49b0
(pernet_ops_rwsem
){++++}-{4:4}
, at: copy_net_ns+0x41e/0x780 net/core/net_namespace.c:577
#1:
ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: register_netdevice_notifier_net+0x23/0xb0 net/core/dev.c:2096
2 locks held by syz-executor/6745:
#0:
ffffffff8a8b49b0
(pernet_ops_rwsem
){++++}-{4:4}
, at: copy_net_ns+0x41e/0x780 net/core/net_namespace.c:577
#1:
ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: register_netdevice_notifier_net+0x23/0xb0 net/core/dev.c:2096
1 lock held by syz-executor/6765:
#0:
ffffffff8a8ccfe8
(
rtnl_mutex){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: inet_rtm_newaddr+0x30c/0x18b0 net/ipv4/devinet.c:978
1 lock held by syz-executor/6769:
#0: ffffffff8a8ccfe8
(rtnl_mutex){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: inet_rtm_newaddr+0x30c/0x18b0 net/ipv4/devinet.c:978
1 lock held by syz-executor/6773:
#0: ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: inet_rtm_newaddr+0x30c/0x18b0 net/ipv4/devinet.c:978
1 lock held by syz-executor/6777:
#0:
ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: inet_rtm_newaddr+0x30c/0x18b0 net/ipv4/devinet.c:978
1 lock held by syz-executor/6781:
#0:
ffffffff8a8ccfe8
(
rtnl_mutex
){+.+.}-{4:4}
, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
, at: inet_rtm_newaddr+0x30c/0x18b0 net/ipv4/devinet.c:978
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x141/0x190 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
watchdog+0xcc3/0xfe0 kernel/hung_task.c:515
kthread+0x3b3/0x730 kernel/kthread.c:463
ret_from_fork+0x6c3/0xa20 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
Sending NMI from CPU 1 to CPUs 0:
yealink 1-1:36.0: urb_irq_callback - urb status -71
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 14 Comm: ksoftirqd/0 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:io_serial_in+0x87/0xb0 drivers/tty/serial/8250/8250_port.c:401
Code: 7b 9f fe 48 8d 7d 40 44 89 e1 48 b8 00 00 00 00 00 fc ff df 48 89 fa d3 e3 48 c1 ea 03 80 3c 02 00 75 1a 66 03 5d 40 89 da ec <5b> 0f b6 c0 5d 41 5c c3 cc cc cc cc e8 18 6a 01 ff eb a2 e8 a1 6a
RSP: 0018:ffffc900000ef1b8 EFLAGS: 00000002
RAX: dffffc0000000060 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff8311c0c0 RDI: ffffffff93f14fc0
RBP: ffffffff93f14f80 R08: 0000000000000001 R09: 000000000000001f
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000020 R14: fffffbfff27e2a4a R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff88826896a000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc8226f3df4 CR3: 0000000114bcc000 CR4: 00000000003506f0
Call Trace:
serial_in drivers/tty/serial/8250/8250.h:128 [inline]
serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
wait_for_lsr+0x13a/0x210 drivers/tty/serial/8250/8250_port.c:1961
fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3234 [inline]
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3257 [inline]
serial8250_console_write+0xdb9/0x1900 drivers/tty/serial/8250/8250_port.c:3342
console_emit_next_record kernel/printk/printk.c:3129 [inline]
console_flush_one_record+0x790/0xe50 kernel/printk/printk.c:3215
console_flush_all kernel/printk/printk.c:3289 [inline]
__console_flush_and_unlock kernel/printk/printk.c:3319 [inline]
console_unlock+0x103/0x260 kernel/printk/printk.c:3359
vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2426
dev_vprintk_emit+0x394/0x3e0 drivers/base/core.c:4914
dev_printk_emit+0xd2/0x10d drivers/base/core.c:4925
__dev_printk+0xcb/0x100 drivers/base/core.c:4937
_dev_err+0xef/0x127 drivers/base/core.c:4980
urb_irq_callback.cold+0x41/0xfd drivers/input/misc/yealink.c:418
__usb_hcd_giveback_urb+0x38d/0x610 drivers/usb/core/hcd.c:1657
usb_hcd_giveback_urb+0x3ca/0x4a0 drivers/usb/core/hcd.c:1741
dummy_timer+0xd85/0x3670 drivers/usb/gadget/udc/dummy_hcd.c:1995
__run_hrtimer kernel/time/hrtimer.c:1777 [inline]
__hrtimer_run_queues+0x516/0x990 kernel/time/hrtimer.c:1841
hrtimer_run_softirq+0x17d/0x350 kernel/time/hrtimer.c:1858
handle_softirqs+0x1dd/0x8f0 kernel/softirq.c:622
run_ksoftirqd kernel/softirq.c:1063 [inline]
run_ksoftirqd+0x38/0x60 kernel/softirq.c:1055
smpboot_thread_fn+0x3d3/0xaa0 kernel/smpboot.c:160
kthread+0x3b3/0x730 kernel/kthread.c:463
ret_from_fork+0x6c3/0xa20 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246