INFO: task kworker/u8:8:1100 blocked for
INFO: task kworker/u8:8:1100 blocked for more than 143 seconds.
Tainted: G L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:8 state:D stack:20872 pid:1100 tgid:1100 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: pm_fs_sync pm_fs_sync_work_fn
Call Trace:
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x1b2a/0x59a0 kernel/sched/core.c:7232
__schedule_loop kernel/sched/core.c:7309 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7324
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7381
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7bf/0x1550 kernel/locking/mutex.c:821
sync_bdevs+0x276/0x470 block/bdev.c:1370
ksys_sync+0xc5/0x120 fs/sync.c:105
ksys_sync_helper+0x17/0xa0 kernel/power/main.c:90
pm_fs_sync_work_fn+0xf/0x70 kernel/power/main.c:112
process_one_work kernel/workqueue.c:3375 [inline]
process_scheduled_works+0xc4e/0x1630 kernel/workqueue.c:3458
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3539
kthread+0x388/0x470 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
Showing all locks held in the system:
locks held by pr/ttyS0/16: 2, last CPU#0:
#0: ffffffff8ea36278 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline]
#0: ffffffff8ea36278 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline]
#0: ffffffff8ea36278 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291
#1: ffffffff9aafec18 (&port_lock_key){-.-.}-{3:3}, at: __uart_port_lock_irqsave include/linux/serial_core.h:613 [inline]
#1: ffffffff9aafec18 (&port_lock_key){-.-.}-{3:3}, at: univ8250_console_device_lock+0x67/0xc0 drivers/tty/serial/8250/8250_core.c:413
locks held by khungtaskd/31: 1, last CPU#1:
#0: ffffffff8eb5c6a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8eb5c6a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8eb5c6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6837
locks held by kworker/u8:8/1100: 3, on CPU#0:
#0: ffff88801f2d2940 ((wq_completion)pm_fs_sync){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88801f2d2940 ((wq_completion)pm_fs_sync){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88801f2d2940 ((wq_completion)pm_fs_sync){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3340 [inline]
#0: ffff88801f2d2940 ((wq_completion)pm_fs_sync){+.+.}-{0:0}, at: process_scheduled_works+0x97e/0x1630 kernel/workqueue.c:3458
#1: ffffc90004f47c40 (pm_fs_sync_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90004f47c40 (pm_fs_sync_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90004f47c40 (pm_fs_sync_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3340 [inline]
#1: ffffc90004f47c40 (pm_fs_sync_work){+.+.}-{0:0}, at: process_scheduled_works+0x97e/0x1630 kernel/workqueue.c:3458
#2: ffff88802725b350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x276/0x470 block/bdev.c:1370
locks held by getty/5368: 2, on CPU#0:
#0: ffff8880326210a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900032262e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by udevd/5640: 1, on CPU#0:
#0: ffff88802725b350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70 block/bdev.c:991
locks held by syz.3.796/7787: 5, on CPU#1:
#0: ffff88801db9f7b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
#1: ffff888053fe4460 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2754 [inline]
#1: ffff888053fe4460 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#2: ffff8880567de480 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 fs/kernfs/file.c:336
#3: ffff88801f29b968 (kn->active#72){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
#3: ffff88801f29b968 (kn->active#72){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540 fs/kernfs/file.c:337
#4: ffffffff8ea04680 (system_transition_mutex){+.+.}-{4:4}, at: enter_state kernel/power/suspend.c:591 [inline]
#4: ffffffff8ea04680 (system_transition_mutex){+.+.}-{4:4}, at: pm_suspend+0x3c7/0x760 kernel/power/suspend.c:644
locks held by kworker/u8:12/9025: 2, last CPU#0:
#0: ffff888030710140 ((wq_completion)wg-kex-wg1#5){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff888030710140 ((wq_completion)wg-kex-wg1#5){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff888030710140 ((wq_completion)wg-kex-wg1#5){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3340 [inline]
#0: ffff888030710140 ((wq_completion)wg-kex-wg1#5){+.+.}-{0:0}, at: process_scheduled_works+0x97e/0x1630 kernel/workqueue.c:3458
#1: ffffc90004c97c40 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90004c97c40 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90004c97c40 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3340 [inline]
#1: ffffc90004c97c40 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97e/0x1630 kernel/workqueue.c:3458
locks held by syz.0.1317/9108: 5, on CPU#0:
#0: ffff88807e5f62b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
#1: ffff88807bcda460 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2754 [inline]
#1: ffff88807bcda460 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#2: ffff888031f81c80 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 fs/kernfs/file.c:336
#3: ffff88801f29b2d8 (kn->active#81){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
#3: ffff88801f29b2d8 (kn->active#81){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540 fs/kernfs/file.c:337
#4: ffffffff8ea04680 (system_transition_mutex){+.+.}-{4:4}, at: lock_system_sleep kernel/power/main.c:71 [inline]
#4: ffffffff8ea04680 (system_transition_mutex){+.+.}-{4:4}, at: pm_test_store+0x95/0x480 kernel/power/main.c:369
locks held by syz.1.1371/9223: 2, on CPU#1:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
#1: ffffffff8ea04680 (system_transition_mutex){+.+.}-{4:4}, at: lock_system_sleep+0x49/0x70 kernel/power/main.c:71
locks held by syz.2.1383/9254: 1, on CPU#1:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz.4.1387/9262: 1, on CPU#1:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz.5.1400/9292: 1, on CPU#0:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz-executor/9296: 1, on CPU#0:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz-executor/9303: 1, on CPU#0:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz-executor/9306: 1, on CPU#1:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz-executor/9307: 1, on CPU#1:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz-executor/9309: 1, on CPU#1:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz-executor/9311: 1, on CPU#0:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz-executor/9315: 1, on CPU#1:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz-executor/9320: 1, on CPU#1:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz-executor/9321: 1, on CPU#0:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
locks held by syz-executor/9325: 1, on CPU#0:
#0: ffffffff8f488fc0 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x350 drivers/char/misc.c:125
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 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+0x17a/0x380 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+0x388/0x470 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 fe 10 5b 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 9f d4 c9 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: 0018:ffffc900001578b8 EFLAGS: 00000002
RAX: 1ffffffff355fd00 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff856c73b0 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff9aafec40 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888124f0c000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5bf9236778 CR3: 000000000e948000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
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+0x388/0x470 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