INFO: task syz.5.3656:21569 blocked for more than 143 seconds.
Tainted: G L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.3656 state:D stack:28552 pid:21569 tgid:21567 ppid:13239 task_flags:0x400140 flags:0x08080002
Call Trace:
context_switch kernel/sched/core.c:5526 [inline]
__schedule+0x17db/0x58f0 kernel/sched/core.c:7276
__schedule_loop kernel/sched/core.c:7353 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7368
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7425
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821
device_lock include/linux/device.h:1104 [inline]
usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
chrdev_open+0x4d9/0x600 fs/char_dev.c:411
do_dentry_open+0x816/0x1380 fs/open.c:996
vfs_open+0x3b/0x340 fs/open.c:1101
do_open fs/namei.c:4837 [inline]
path_openat+0x1443/0x1d60 fs/namei.c:5000
do_file_open+0x23e/0x4a0 fs/namei.c:5029
do_sys_openat2+0x115/0x200 fs/open.c:1417
do_sys_open fs/open.c:1423 [inline]
__do_compat_sys_openat fs/open.c:1485 [inline]
__se_compat_sys_openat fs/open.c:1483 [inline]
__ia32_compat_sys_openat+0x131/0x160 fs/open.c:1483
do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
do_int80_emulation+0x198/0x500 arch/x86/entry/syscall_32.c:166
asm_int80_emulation+0x1a/0x20 arch/x86/include/asm/idtentry.h:598
RIP: 0023:0xf71675ab
RSP: 002b:00000000f53fc03c EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 00000000f53fc100
RDX: 0000000000109301 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Showing all locks held in the system:
locks held by khungtaskd/32: 1, last CPU#1:
#0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by getty/5372: 2, on CPU#0:
#0: ffff8880363ec0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by kworker/0:5/18158: 5, on CPU#0:
#0: ffff888022a85540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff888022a85540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff888022a85540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#0: ffff888022a85540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#1: ffffc90003ea7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90003ea7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90003ea7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#1: ffffc90003ea7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#2: ffff88802982f1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff88802982f1d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912
#3: ffff88807eeb21d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff88807eeb21d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073
#4: ffff888049a0f1a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff888049a0f1a0 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073
locks held by kworker/1:0/19764: 6, on CPU#1:
#0: ffff888022a85540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff888022a85540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff888022a85540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#0: ffff888022a85540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#1: ffffc900042d7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc900042d7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc900042d7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#1: ffffc900042d7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#2: ffff88802997b1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff88802997b1d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912
#3: ffff88802997f568 (&port_dev->status_lock){+.+.}-{4:4}, at: usb_lock_port drivers/usb/core/hub.c:3265 [inline]
#3: ffff88802997f568 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5477 [inline]
#3: ffff88802997f568 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5720 [inline]
#3: ffff88802997f568 (&port_dev->status_lock){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5884 [inline]
#3: ffff88802997f568 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x20a1/0x4d30 drivers/usb/core/hub.c:5966
#4: ffff888029917260 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5478 [inline]
#4: ffff888029917260 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5720 [inline]
#4: ffff888029917260 (hcd->address0_mutex){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5884 [inline]
#4: ffff888029917260 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x20c9/0x4d30 drivers/usb/core/hub.c:5966
#5: ffffffff8fafb968 (ehci_cf_port_reset_rwsem){.+.+}-{4:4}, at: hub_port_reset+0x14d/0x1810 drivers/usb/core/hub.c:3080
locks held by syz.5.3656/21569: 1, on CPU#0:
#0: ffff88802982f1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802982f1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.8.4038/23289: 1, on CPU#1:
#0: ffff88802982f1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#0: ffff88802982f1d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x151/0x770 drivers/usb/core/devio.c:1054
locks held by syz.6.4160/23865: 1, on CPU#1:
#0: ffff888069cd8260 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff888069cd8260 (sk_lock-AF_INET){+.+.}-{0:0}, at: sk_wait_data+0x301/0x4d0 net/core/sock.c:3314
locks held by syz.6.4160/23867: 1, last CPU#0:
#0: ffff888069cd8260 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff888069cd8260 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendmsg+0x21/0x50 net/ipv4/tcp.c:1451
locks held by syz.3.4162/23876: 2, last CPU#0:
#0: ffff88801b09dcf8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:600 [inline]
#0: ffff88801b09dcf8 (&mm->mmap_lock){++++}-{4:4}, at: __mm_populate+0x182/0x390 mm/gup.c:1942
#1: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x240 mm/pgtable-generic.c:290
locks held by syz.4.4163/23880: 7, last CPU#1:
#0: ffff8880365be460 (sb_writers#10){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:494
#1: ffff888035010f80 (&type->i_mutex_dir_key#7/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline]
#1: ffff888035010f80 (&type->i_mutex_dir_key#7/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline]
#1: ffff888035010f80 (&type->i_mutex_dir_key#7/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline]
#1: ffff888035010f80 (&type->i_mutex_dir_key#7/1){+.+.}-{4:4}, at: filename_rmdir+0x1cd/0x520 fs/namei.c:5565
#2: ffff8880798d6740 (&type->i_mutex_dir_key#7){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
#2: ffff8880798d6740 (&type->i_mutex_dir_key#7){++++}-{4:4}, at: vfs_rmdir+0xf8/0x6a0 fs/namei.c:5500
#3: ffffffff8ed9c760 (cgroup_mutex){+.+.}-{4:4}, at: cgroup_lock include/linux/cgroup.h:482 [inline]
#3: ffffffff8ed9c760 (cgroup_mutex){+.+.}-{4:4}, at: cgroup_kn_lock_live+0x13c/0x230 kernel/cgroup/cgroup.c:1719
#4: ffff888029fdb2a0 (&root->kernfs_supers_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3f/0x140 fs/kernfs/dir.c:1791
#5: ffff888029fdb180 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x4e/0x140 fs/kernfs/dir.c:1792
#6: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#6: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#6: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
#6: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: kernfs_root+0x1c/0x230 fs/kernfs/kernfs-internal.h:76
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 32 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123
nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66
trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xfd7/0x1030 kernel/hung_task.c:561
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 16 Comm: pr/ttyS0 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409
Code: e8 1e 35 55 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 0f 35 c5 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07
RSP: 0000:ffffc900001578b8 EFLAGS: 00000002
RAX: 1ffffffff35a7200 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff85729520 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff9ad390c0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888124cd2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000034110ff8 CR3: 000000007944e000 CR4: 00000000003526f0
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+0x184/0x2f0 drivers/tty/serial/8250/8250_port.c:2013
serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3270 [inline]
__serial8250_console_fifo_write+0xcd/0x3e0 drivers/tty/serial/8250/8250_port.c:3345
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3378 [inline]
__serial8250_console_write drivers/tty/serial/8250/8250_port.c:3429 [inline]
serial8250_console_write+0xaa1/0x1200 drivers/tty/serial/8250/8250_port.c:3493
nbcon_emit_next_record+0xef5/0x1a90 kernel/printk/nbcon.c:-1
nbcon_emit_one kernel/printk/nbcon.c:1157 [inline]
nbcon_kthread_func+0x679/0x880 kernel/printk/nbcon.c:1271
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245