INFO: task syz.4.1356:10337 blocked for more than 143 seconds.
Tainted: G L syzkaller #0
Tainted: G L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.1356 state:D stack:25528 pid:10337 tgid:10336 ppid:6209 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5402 [inline]
__schedule+0x16f9/0x5500 kernel/sched/core.c:7204
__schedule_loop kernel/sched/core.c:7283 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7298
cgroup_lock_and_drain_offline+0x516/0x650 kernel/cgroup/cgroup.c:3248
cgroup_kn_lock_live+0x120/0x230 kernel/cgroup/cgroup.c:1699
cgroup_subtree_control_write+0x4b3/0x10a0 kernel/cgroup/cgroup.c:3550
cgroup_file_write+0x331/0x8f0 kernel/cgroup/cgroup.c:4289
kernfs_fop_write_iter+0x3b0/0x540 fs/kernfs/file.c:352
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x629/0xba0 fs/read_write.c:688
ksys_write+0x156/0x270 fs/read_write.c:740
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f377992ce59
RSP: 002b:00007f3777b86028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f3779ba5fa0 RCX: 00007f377992ce59
RDX: 0000000000000006 RSI: 0000200000000040 RDI: 0000000000000008
RBP: 00007f37799c2d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3779ba6038 R14: 00007f3779ba5fa0 R15: 00007ffced183328
Showing all locks held in the system:
4 locks held by pr/legacy/17:
#0: ffffffff8e1bccc0 (console_lock){+.+.}-{0:0}, at: legacy_kthread_func+0x1a3/0x250 kernel/printk/printk.c:3711
#1: ffffffff8e0a45b8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline]
#1: ffffffff8e0a45b8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline]
#1: ffffffff8e0a45b8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline]
#1: ffffffff8e0a45b8 (console_srcu){....}-{0:0}, at: console_flush_one_record+0xfa/0xb90 kernel/printk/printk.c:3246
#2: ffffffff99e10018 (&port_lock_key){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
#2: ffffffff99e10018 (&port_lock_key){+.+.}-{3:3}, at: uart_port_lock_irqsave include/linux/serial_core.h:719 [inline]
#2: ffffffff99e10018 (&port_lock_key){+.+.}-{3:3}, at: serial8250_console_write+0x178/0x1b50 drivers/tty/serial/8250/8250_port.c:3338
#3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
#3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57
1 lock held by khungtaskd/39:
#0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6777
3 locks held by kworker/u8:7/1035:
#0: ffff88813fe54138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293
#1: ffffc90005f3fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294
#2: ffffffff8f5ac9f8 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:313
3 locks held by kworker/u8:16/3421:
#0: ffff8880334d6938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293
#1: ffffc9000ecefc40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294
#2: ffffffff8f5ac9f8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#2: ffffffff8f5ac9f8 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x124/0x1680 net/ipv6/addrconf.c:4221
2 locks held by getty/5370:
#0: ffff888029ab50a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90003cbe2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13a0 drivers/tty/n_tty.c:2211
6 locks held by kworker/1:4/5600:
#0: ffff88801af22138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293
#1: ffffc900044e7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294
#2: ffff88802a398210 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
#2: ffff88802a398210 (&dev->mutex){....}-{4:4}, at: hub_event+0x17c/0x4f60 drivers/usb/core/hub.c:5899
#3: ffff88802a468658 (&port_dev->status_lock){+.+.}-{4:4}, at: usb_lock_port drivers/usb/core/hub.c:3252 [inline]
#3: ffff88802a468658 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5464 [inline]
#3: ffff88802a468658 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
#3: ffff88802a468658 (&port_dev->status_lock){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5871 [inline]
#3: ffff88802a468658 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x21b0/0x4f60 drivers/usb/core/hub.c:5953
#4: ffff8880295e8e58 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5465 [inline]
#4: ffff8880295e8e58 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
#4: ffff8880295e8e58 (hcd->address0_mutex){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5871 [inline]
#4: ffff8880295e8e58 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x21e0/0x4f60 drivers/usb/core/hub.c:5953
#5: ffffffff8ee53c20 (ehci_cf_port_reset_rwsem){.+.+}-{4:4}, at: hub_port_reset+0x14e/0x1820 drivers/usb/core/hub.c:3067
10 locks held by kworker/0:4/5716:
#0: ffff88813fe16538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293
#1: ffffc90005107c40 ((work_completion)(&(&tbl->gc_work)->work)){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294
#2: ffffffff8e0613c0 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#4: ffffffff8f6db1b8 (&tbl->lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock_rt.h:90 [inline]
#4: ffffffff8f6db1b8 (&tbl->lock){+...}-{3:3}, at: neigh_periodic_work+0xc64/0xe90 net/core/neighbour.c:1040
#5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
#5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57
#6: ffffffff8e0613c0 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#7: ffff88802a55a0a8 (&n->lock){++..}-{3:3}, at: read_lock_bh include/linux/rwlock_rt.h:45 [inline]
#7: ffff88802a55a0a8 (&n->lock){++..}-{3:3}, at: neigh_notify net/core/neighbour.c:3594 [inline]
#7: ffff88802a55a0a8 (&n->lock){++..}-{3:3}, at: neigh_cleanup_and_release+0xb1/0x2d0 net/core/neighbour.c:119
#8: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#8: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#8: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rt_read_lock+0x277/0x4b0 kernel/locking/spinlock_rt.c:234
#9: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#9: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#9: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __neigh_notify+0x29/0x310 net/core/neighbour.c:3571
3 locks held by syz.4.1356/10337:
#0: ffff888038b22728 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1260
#1: ffff888033cee480 (sb_writers#9){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
#1: ffff888033cee480 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x22d/0xba0 fs/read_write.c:684
#2: ffff88805c3c4078 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1df/0x540 fs/kernfs/file.c:343
2 locks held by syz.7.2124/12794:
#0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: blk_mq_dispatch_queue_requests+0x11a/0x800 block/blk-mq.c:2903
#1: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#1: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#1: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
#1: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xa6/0x2550 arch/x86/kernel/unwind_orc.c:495
7 locks held by syz.8.2145/12860:
#0: ffffffff8f5ac9f8 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:641 [inline]
#0: ffffffff8f5ac9f8 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3505
#1: ffffffff8e0613c0 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#2: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#3: ffff88803e79e328 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock_rt.h:90 [inline]
#3: ffff88803e79e328 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{3:3}, at: dev_reset_queue+0x144/0x1f0 include/net/sch_generic.h:752
#4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
#4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57
#5: ffffffff8e0613c0 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#6: ffff88803e79e230 (&sch->root_lock_key#9){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock_rt.h:90 [inline]
#6: ffff88803e79e230 (&sch->root_lock_key#9){+...}-{3:3}, at: dev_reset_queue+0x160/0x1f0 include/net/sch_generic.h:753
2 locks held by syz.6.2153/12881:
#0: ffff88803c8d8928 (nlk_cb_mutex-ROUTE){+.+.}-{4:4}, at: __netlink_dump_start+0xfe/0x7e0 net/netlink/af_netlink.c:2410
#1: ffffffff8f5ac9f8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
#1: ffffffff8f5ac9f8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dumpit+0x92/0x200 net/core/rtnetlink.c:6930
1 lock held by syz.6.2153/12882:
#0: ffff88803c8d8928 (nlk_cb_mutex-ROUTE){+.+.}-{4:4}, at: __netlink_dump_start+0xfe/0x7e0 net/netlink/af_netlink.c:2410
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 39 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122
nmi_trigger_cpumask_backtrace+0x17a/0x380 lib/nmi_backtrace.c:65
trigger_all_cpu_backtrace include/linux/nmi.h:162 [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+0xfd3/0x1030 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: 17 Comm: pr/legacy Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:401
Code: e8 de 35 7a 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 1f e1 e4 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:ffffc900001679f0 EFLAGS: 00000202
RAX: 1ffffffff33c2000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffffff99e102d0 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff854b6470 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff99e10040 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888125c7e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6ba123cd58 CR3: 00000000373c4000 CR4: 00000000003526f0
DR0: 0000000000000008 DR1: 0000000000000007 DR2: 0000000000000004
DR3: 0000000000000008 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+0x1aa/0x2f0 drivers/tty/serial/8250/8250_port.c:1982
serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3229 [inline]
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3294 [inline]
serial8250_console_write+0x114b/0x1b50 drivers/tty/serial/8250/8250_port.c:3379
console_emit_next_record kernel/printk/printk.c:3163 [inline]
console_flush_one_record+0x68b/0xb90 kernel/printk/printk.c:3269
legacy_kthread_func+0x1b6/0x250 kernel/printk/printk.c:3712
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