INFO: task kworker/u8:0:12 blocked in I/O wait for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kerne
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:0 state:D stack:21728 pid:12 tgid:12 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: writeback wb_workfn (flush-7:6)
Call Trace:
context_switch kernel/sched/core.c:5533 [inline]
__schedule+0x16d9/0x5700 kernel/sched/core.c:7284
__schedule_loop kernel/sched/core.c:7361 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7376
io_schedule+0x80/0xe0 kernel/sched/core.c:8220
TXN_SLEEP_DROP_LOCK fs/jfs/jfs_txnmgr.c:125 [inline]
txBegin+0x281/0xbe0 fs/jfs/jfs_txnmgr.c:376
jfs_commit_inode+0x1b3/0x530 fs/jfs/inode.c:107
jfs_write_inode+0x145/0x220 fs/jfs/inode.c:138
write_inode fs/fs-writeback.c:1623 [inline]
__writeback_single_inode+0x6a0/0x1230 fs/fs-writeback.c:1866
writeback_sb_inodes+0x9db/0x1ab0 fs/fs-writeback.c:2114
wb_writeback+0x41c/0xad0 fs/fs-writeback.c:2299
wb_do_writeback fs/fs-writeback.c:2467 [inline]
wb_workfn+0x437/0x10f0 fs/fs-writeback.c:2512
process_one_work kernel/workqueue.c:3396 [inline]
process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
kthread+0x38b/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
INFO: task syz-executor:6812 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:22104 pid:6812 tgid:6812 ppid:1 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5533 [inline]
__schedule+0x16d9/0x5700 kernel/sched/core.c:7284
__schedule_loop kernel/sched/core.c:7361 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7376
wb_wait_for_completion+0x3b2/0x700 fs/fs-writeback.c:227
__writeback_inodes_sb_nr+0x246/0x2e0 fs/fs-writeback.c:2968
sync_filesystem+0xa5/0x250 fs/sync.c:54
generic_shutdown_super+0x77/0x2d0 fs/super.c:730
kill_block_super+0x44/0xa0 fs/super.c:1903
deactivate_locked_super+0xbe/0x110 fs/super.c:586
cleanup_mnt+0x3d3/0x460 fs/namespace.c:1317
task_work_run+0x1d9/0x270 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
exit_to_user_mode_loop+0x204/0x770 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline]
do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7c4192f397
RSP: 002b:00007fff9cf1ce18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f7c419c44bb RCX: 00007f7c4192f397
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff9cf1ced0
RBP: 00007fff9cf1ced0 R08: 00007fff9cf1ded0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff9cf1df60
R13: 00007f7c419c44bb R14: 00000000000402c1 R15: 00007fff9cf1dfa0
Showing all locks held in the system:
locks held by kworker/u8:0/12: 2, on CPU#0:
#0: ffff88801aeb5138 ((wq_completion)writeback){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88801aeb5138 ((wq_completion)writeback){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88801aeb5138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#0: ffff88801aeb5138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#1: ffffc90000117c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90000117c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90000117c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#1: ffffc90000117c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
locks held by pr/ttyS0/17: 3, last CPU#1:
#0: ffffffff8e09d7d8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline]
#0: ffffffff8e09d7d8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline]
#0: ffffffff8e09d7d8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291
#1: ffffffff99eab418 (&port_lock_key){+.+.}-{3:3}, at: nbcon_emit_one kernel/printk/nbcon.c:1137 [inline]
#1: ffffffff99eab418 (&port_lock_key){+.+.}-{3:3}, at: nbcon_kthread_func+0x64c/0x880 kernel/printk/nbcon.c:1271
#2: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#2: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#2: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
#2: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
locks held by khungtaskd/37: 1, last CPU#0:
#0: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by kworker/u8:5/76: 3, on CPU#0:
#0: ffff888033473138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff888033473138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff888033473138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#0: ffff888033473138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#1: ffffc9000157fc40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc9000157fc40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc9000157fc40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#1: ffffc9000157fc40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#2: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline]
#2: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x123/0x16e0 net/ipv6/addrconf.c:4230
locks held by kworker/0:2/200: 3, on CPU#0:
#0: ffff88813ff27938 ((wq_completion)events){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88813ff27938 ((wq_completion)events){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88813ff27938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#0: ffff88813ff27938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#1: ffffc9000423fc40 (netdev_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc9000423fc40 (netdev_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc9000423fc40 (netdev_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#1: ffffc9000423fc40 (netdev_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#2: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: netdev_work_proc+0x72/0x7f0 net/core/netdev_work.c:132
locks held by kworker/u8:8/1015: 3, on CPU#0:
#0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#1: ffffc90006027c40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90006027c40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90006027c40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#1: ffffc90006027c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#2: ffffffff8f5c7140 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810 net/core/net_namespace.c:677
locks held by getty/5338: 2, on CPU#1:
#0: ffff88803656a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900044c32e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x460/0x1360 drivers/tty/n_tty.c:2211
locks held by syz-executor/6812: 1, on CPU#0:
#0: ffff88803c35a0e0 (&type->s_umount_key#69){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
#0: ffff88803c35a0e0 (&type->s_umount_key#69){++++}-{4:4}, at: __super_lock_excl fs/super.c:75 [inline]
#0: ffff88803c35a0e0 (&type->s_umount_key#69){++++}-{4:4}, at: deactivate_super+0xac/0xe0 fs/super.c:613
locks held by syz-executor/9362: 1, on CPU#0:
#0: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline]
#0: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0 net/ipv4/devinet.c:978
locks held by syz-executor/9373: 1, on CPU#0:
#0: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline]
#0: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: inet6_rtm_newaddr+0x667/0xe00 net/ipv6/addrconf.c:5063
locks held by syz-executor/9399: 1, on CPU#0:
#0: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline]
#0: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0 net/ipv4/devinet.c:978
locks held by syz-executor/9469: 9, last CPU#0:
#0: ffff888034fa6510 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
#0: ffff888034fa6510 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
#1: ffff88803b233078 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d9/0x540 fs/kernfs/file.c:336
#2: ffff88802a21cd28 (kn->active#52){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
#2: ffff88802a21cd28 (kn->active#52){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22c/0x540 fs/kernfs/file.c:337
#3: ffffffff8ee45df8 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: new_device_store+0x13c/0x6d0 drivers/net/netdevsim/bus.c:184
#4: ffff8880432d4160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff8880432d4160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073
#5: ffff8880564d0310 (&devlink->lock_key#27){+.+.}-{4:4}, at: nsim_drv_probe+0xfb/0xbc0 drivers/net/netdevsim/dev.c:1583
#6: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: nsim_init_netdevsim drivers/net/netdevsim/netdev.c:1060 [inline]
#6: ffffffff8f5d5978 (rtnl_mutex){+.+.}-{4:4}, at: nsim_create+0x87f/0x1160 drivers/net/netdevsim/netdev.c:1154
#7: ffffffff8f5c7080 (net_rwsem){++++}-{4:4}, at: wireless_nlevent_flush net/wireless/wext-core.c:350 [inline]
#7: ffffffff8f5c7080 (net_rwsem){++++}-{4:4}, at: wext_netdev_notifier_call+0x28/0x110 net/wireless/wext-core.c:370
#8: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#8: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#8: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
#8: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
locks held by syz.6.351/9707: 2, last CPU#0:
#0: ffff888067c92510 (sb_writers#5){.+.+}-{0:0}, at: direct_splice_actor+0x49/0x160 fs/splice.c:1158
#1: ffffffff8e3119f0 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:198 [inline]
#1: ffffffff8e3119f0 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_read_lock+0x27/0x60 include/linux/srcu.h:305
locks held by dhcpcd-run-hook/9719: 1, last CPU#1:
#0: ffff88803faf5eb8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock include/linux/mmap_lock.h:544 [inline]
#0: ffff88803faf5eb8 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x2d8/0x9f0 mm/mmap.c:1323
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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/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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 17 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409
Code: e8 ee 76 64 fc 44 89 f9 d3 e3 49 83 ee 80 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 3f 72 d0 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:ffffc900001678b8 EFLAGS: 00000202
RAX: 1ffffffff33d5600 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff85625e70 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff99eab440 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888125cc2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4a06767368 CR3: 00000000254ec000 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+0x190/0x300 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+0xd0/0x3f0 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+0xac5/0x1230 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/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