INFO: task syz.4.3365:18647 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.4.3365 state:D stack:27608 pid:18647 tgid:18646 ppid:15685 task_flags:0x400040 flags:0x00080802
Call Trace:
context_switch kernel/sched/core.c:5533 [inline]
__schedule+0x1259/0x6920 kernel/sched/core.c:7284
__schedule_loop kernel/sched/core.c:7361 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7376
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7433
rwsem_down_read_slowpath+0x5af/0xb40 kernel/locking/rwsem.c:1114
__down_read_common kernel/locking/rwsem.c:1291 [inline]
__down_read kernel/locking/rwsem.c:1304 [inline]
down_read+0xed/0x4c0 kernel/locking/rwsem.c:1576
__super_lock fs/super.c:62 [inline]
super_lock+0x326/0x3f0 fs/super.c:124
__iterate_supers+0x38b/0x4a0 fs/super.c:979
ksys_sync+0x87/0xf0 fs/sync.c:102
__do_sys_sync+0xe/0x20 fs/sync.c:111
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc07819e159
RSP: 002b:00007fc07910c028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fc078425fa0 RCX: 00007fc07819e159
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fc078425fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc078426038 R14: 00007fc078425fa0 R15: 00007ffd58366ba8
Showing all locks held in the system:
locks held by pr/ttyS0/16: 2, last CPU#1:
#0: ffffffff8edd88b8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline]
#0: ffffffff8edd88b8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline]
#0: ffffffff8edd88b8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x49/0x60 kernel/printk/printk.c:291
#1: ffffffff9bc75f38 (&port_lock_key){-.-.}-{3:3}, at: __uart_port_lock_irqsave include/linux/serial_core.h:613 [inline]
#1: ffffffff9bc75f38 (&port_lock_key){-.-.}-{3:3}, at: univ8250_console_device_lock+0x64/0xc0 drivers/tty/serial/8250/8250_core.c:413
locks held by khungtaskd/32: 1, last CPU#0:
#0: ffffffff8edec5a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8edec5a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8edec5a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6871
locks held by kworker/u8:9/1166: 5, last CPU#0:
#0: ffff88801c094140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc90005317d08 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
#2: ffffffff8ec7cb10 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_disable+0x12/0x20 kernel/jump_label.c:247
#3: ffffffff8ef41500 (jump_label_mutex){+.+.}-{4:4}, at: jump_label_lock kernel/jump_label.c:27 [inline]
#3: ffffffff8ef41500 (jump_label_mutex){+.+.}-{4:4}, at: static_key_disable_cpuslocked+0x110/0x1c0 kernel/jump_label.c:238
#4: ffffffff8ec9c480 (text_mutex){+.+.}-{4:4}, at: arch_jump_label_transform_apply+0x17/0x30 arch/x86/kernel/jump_label.c:145
locks held by getty/5363: 2, on CPU#0:
#0: ffff888038ad40a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc900032262e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211
locks held by kworker/u8:43/11033: 2, on CPU#0:
#0: ffff88801c094140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc90004db7d08 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
locks held by syz.2.3040/17191: 2, on CPU#0:
#0: ffff88802e86a0e8 (&type->s_umount_key#96){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
#0: ffff88802e86a0e8 (&type->s_umount_key#96){++++}-{4:4}, at: __super_lock_excl fs/super.c:75 [inline]
#0: ffff88802e86a0e8 (&type->s_umount_key#96){++++}-{4:4}, at: deactivate_super fs/super.c:613 [inline]
#0: ffff88802e86a0e8 (&type->s_umount_key#96){++++}-{4:4}, at: deactivate_super+0xe2/0x110 fs/super.c:610
#1: ffffffff8f2899c0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:582
locks held by syz.4.3365/18647: 1, on CPU#1:
#0: ffff88802e86a0e8 (&type->s_umount_key#96){++++}-{4:4}, at: __super_lock fs/super.c:62 [inline]
#0: ffff88802e86a0e8 (&type->s_umount_key#96){++++}-{4:4}, at: super_lock+0x326/0x3f0 fs/super.c:124
locks held by syz-executor/18757: 2, last CPU#0:
#0: ffff888037f34460 (sb_writers#6){.+.+}-{0:0}, at: filename_unlinkat+0x1ad/0x730 fs/namei.c:5696
#1: ffffffff8edec5a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffffff8edec5a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffffff8edec5a0 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
#1: ffffffff8edec5a0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xbd/0x2090 arch/x86/kernel/unwind_orc.c:495
locks held by kworker/u8:2/19763: 3, last CPU#1:
#0: ffff88801c094140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc9000205fd08 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
#2: ffff888031385258 (&devlink->lock_key#7){+.+.}-{4:4}, at: nsim_dev_trap_report_work+0x56/0xd20 drivers/net/netdevsim/dev.c:834
locks held by syz.5.3718/19950: 1, on CPU#1:
#0: ffff88802e86a0e8 (&type->s_umount_key#96){++++}-{4:4}, at: __super_lock fs/super.c:62 [inline]
#0: ffff88802e86a0e8 (&type->s_umount_key#96){++++}-{4:4}, at: super_lock+0x326/0x3f0 fs/super.c:124
locks held by syz-executor/20130: 8, last CPU#0:
#0: ffff888037928460 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
#1: ffff88804a670880 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336
#2: ffff88802b17c878 (kn->active#52){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
#2: ffff88802b17c878 (kn->active#52){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x332/0x5f0 fs/kernfs/file.c:337
#3: ffffffff9023af40 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: new_device_store+0xfe/0x6d0 drivers/net/netdevsim/bus.c:184
#4: ffff88807e0bf128 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff88807e0bf128 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1073
#5: ffff88807e0bd258 (&devlink->lock_key#15){+.+.}-{4:4}, at: nsim_drv_probe+0xcd/0x1350 drivers/net/netdevsim/dev.c:1583
#6: ffffffff90cd4b40 (rtnl_mutex){+.+.}-{4:4}, at: register_nexthop_notifier+0x1b/0x70 net/ipv4/nexthop.c:4044
#7: ffff888056682e60 (&(&net->nexthop.notifier_chain)->rwsem){++++}-{4:4}, at: __blocking_notifier_chain_register kernel/notifier.c:263 [inline]
#7: ffff888056682e60 (&(&net->nexthop.notifier_chain)->rwsem){++++}-{4:4}, at: blocking_notifier_chain_register+0x60/0xd0 kernel/notifier.c:282
locks held by syz.6.3789/20328: 1, on CPU#0:
#0: ffffffff8edf8378 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x48/0x6d0 kernel/rcu/tree.c:3904
locks held by rm/20341: 1, last CPU#0:
#0: ffff888038b80f80 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock include/linux/mmap_lock.h:544 [inline]
#0: ffff888038b80f80 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x22c/0xa00 mm/mmap.c:1323
locks held by kworker/u8:43/20343: 1, last CPU#0:
#0: ffff888031006420 (&sig->cred_guard_mutex){+.+.}-{4:4}, at: prepare_bprm_creds fs/exec.c:1424 [inline]
#0: ffff888031006420 (&sig->cred_guard_mutex){+.+.}-{4:4}, at: bprm_execve+0xa3/0x1940 fs/exec.c:1847
=============================================
NMI backtrace for cpu 0
CPU: 0 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 09/16/2026
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:123
nmi_trigger_cpumask_backtrace+0x21f/0x2a0 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+0x141/0x190 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xcb1/0x1030 kernel/hung_task.c:561
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 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 09/16/2026
RIP: 0010:io_serial_in+0x87/0xb0 drivers/tty/serial/8250/8250_port.c:410
Code: a3 5a fc 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 e9 bd 15 24 06 e8 88 0d ce fc eb a2 e8 11 0e
RSP: 0018:ffffc90000157958 EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff85b1a170 RDI: ffffffff9bc75f60
RBP: ffffffff9bc75f20 R08: 0000000000000001 R09: 000000000000001f
R10: 0000000000000000 R11: 205d313835303154 R12: 0000000000000000
R13: 0000000000000020 R14: fffffbfff378ec41 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888123c4f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5446754286 CR3: 000000003af3b000 CR4: 00000000003526f0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000002
DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400
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:2013
serial8250_fifo_wait_for_lsr_thre+0x5f/0xd0 drivers/tty/serial/8250/8250_port.c:3270
__serial8250_console_fifo_write+0xa5/0x290 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+0xf46/0x1330 drivers/tty/serial/8250/8250_port.c:3493
nbcon_emit_next_record+0x8f7/0xa70 kernel/printk/nbcon.c:1070
nbcon_emit_one+0x1a8/0x2b0 kernel/printk/nbcon.c:1157
nbcon_kthread_func+0x613/0x7d0 kernel/printk/nbcon.c:1271
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245