INFO: task syz.3.5474:23387 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.3.5474 state:D stack:24296 pid:23387 tgid:23386 ppid:14940 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5526 [inline]
__schedule+0x17db/0x58f0 kernel/sched/core.c:7277
__schedule_loop kernel/sched/core.c:7354 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7369
cgroup_lock_and_drain_offline+0x51a/0x650 kernel/cgroup/cgroup.c:3350
cgroup_kn_lock_live+0x120/0x230 kernel/cgroup/cgroup.c:1717
cgroup_subtree_control_write+0x4b5/0x1080 kernel/cgroup/cgroup.c:3652
cgroup_file_write+0x331/0x8f0 kernel/cgroup/cgroup.c:4412
kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x612/0xba0 fs/read_write.c:687
ksys_write+0x150/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2cd359e159
RSP: 002b:00007f2cd44c9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f2cd3825fa0 RCX: 00007f2cd359e159
RDX: 0000000000000005 RSI: 0000200000000300 RDI: 0000000000000008
RBP: 00007f2cd363506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2cd3826038 R14: 00007f2cd3825fa0 R15: 00007f2cd394fa48
Showing all locks held in the system:
locks held by pr/ttyS0/16: 2, last CPU#1:
#0: ffffffff8ec364f8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline]
#0: ffffffff8ec364f8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline]
#0: ffffffff8ec364f8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291
#1: ffffffff9ad3a098 (&port_lock_key){-.-.}-{3:3}, at: __uart_port_lock_irqsave include/linux/serial_core.h:613 [inline]
#1: ffffffff9ad3a098 (&port_lock_key){-.-.}-{3:3}, at: univ8250_console_device_lock+0x67/0xc0 drivers/tty/serial/8250/8250_core.c:413
locks held by khungtaskd/32: 1, last CPU#0:
#0: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by udevd/4982: 1, last CPU#0:
#0: ffffffff8eeac3f0 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:198 [inline]
#0: ffffffff8eeac3f0 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_read_lock+0x27/0x60 include/linux/srcu.h:305
locks held by getty/5371: 2, on CPU#1:
#0: ffff888035c5c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by kworker/0:0/16113: 2, last CPU#0:
#0: ffff88801b069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88801b069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88801b069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#0: ffff88801b069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#1: ffffc9000b8dfc40 ((gc_work).work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc9000b8dfc40 ((gc_work).work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc9000b8dfc40 ((gc_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#1: ffffc9000b8dfc40 ((gc_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
locks held by kworker/u8:36/20248: 3, last CPU#0:
#0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#1: ffffc90007207c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90007207c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90007207c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#1: ffffc90007207c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#2: ffff88804d6ef258 (&devlink->lock_key#16){+.+.}-{4:4}, at: nsim_dev_trap_report_work+0x57/0xb40 drivers/net/netdevsim/dev.c:834
locks held by syz.3.5474/23387: 3, on CPU#0:
#0: ffff8880123040f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
#1: ffff88807d19a460 (sb_writers#9){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
#1: ffff88807d19a460 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#2: ffff88802c644c80 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 fs/kernfs/file.c:336
locks held by kworker/1:2/23934: 4, on CPU#1:
#0: ffff8880222c1d40 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff8880222c1d40 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff8880222c1d40 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#0: ffff8880222c1d40 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#1: ffffc90007307c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90007307c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90007307c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#1: ffffc90007307c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#2: ffff88802a0b01d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff88802a0b01d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912
#3: ffff88803f56d1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff88803f56d1d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073
locks held by syz.5.6133/25407: 3, last CPU#0:
#0: ffff8880557fe460 (sb_writers#5){.+.+}-{0:0}, at: do_coredump fs/coredump.c:1126 [inline]
#0: ffff8880557fe460 (sb_writers#5){.+.+}-{0:0}, at: vfs_coredump+0x3764/0x4520 fs/coredump.c:1195
#1: ffff8880898b7b28 (&sb->s_type->i_mutex_key#15){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
#1: ffff8880898b7b28 (&sb->s_type->i_mutex_key#15){++++}-{4:4}, at: shmem_file_write_iter+0x7f/0x120 mm/shmem.c:3430
#2: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#2: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#2: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
#2: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550 arch/x86/kernel/unwind_orc.c:495
locks held by syz.4.6148/25447: 3, last CPU#0:
#0: ffffffff90244b08 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x524/0x780 net/core/net_namespace.c:578
#1: ffffffff90253380 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch+0xd0/0x760 net/core/dev.c:13262
#2: ffff88801c2d4aa0 (&root->kernfs_supers_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3f/0x140 fs/kernfs/dir.c:1791
locks held by syz.6.6151/25459: 1, on CPU#1:
#0: ffff8880354e83b8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:562 [inline]
#0: ffff8880354e83b8 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x1dd/0x4e0 mm/util.c:579
locks held by syz.6.6151/25460: 2, on CPU#0:
#0: ffffffff90244b08 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x524/0x780 net/core/net_namespace.c:578
#1: ffffffff90253380 (rtnl_mutex){+.+.}-{4:4}, at: ip_tunnel_init_net+0x2d5/0x820 net/ipv4/ip_tunnel.c:1136
locks held by syz.6.6151/25461: 2, on CPU#0:
#0: ffffffff90244b08 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x524/0x780 net/core/net_namespace.c:578
#1: ffffffff90253380 (rtnl_mutex){+.+.}-{4:4}, at: ip_tunnel_init_net+0x2d5/0x820 net/ipv4/ip_tunnel.c:1136
locks held by syz.6.6151/25462: 2, last CPU#0:
#0: ffff8880354e83b8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:600 [inline]
#0: ffff8880354e83b8 (&mm->mmap_lock){++++}-{4:4}, at: __mm_populate+0x182/0x390 mm/gup.c:1942
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: do_fault_around mm/memory.c:5957 [inline]
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: do_read_fault mm/memory.c:5991 [inline]
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: do_fault mm/memory.c:6134 [inline]
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: do_pte_missing+0x140c/0x34b0 mm/memory.c:4700
locks held by syz.1.6153/25466: 1, on CPU#0:
#0: ffff88805531f678 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:562 [inline]
#0: ffff88805531f678 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x1dd/0x4e0 mm/util.c:579
locks held by syz.1.6153/25468: 2, last CPU#0:
#0: ffff88805531f678 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:600 [inline]
#0: ffff88805531f678 (&mm->mmap_lock){++++}-{4:4}, at: __mm_populate+0x182/0x390 mm/gup.c:1942
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x240 mm/pgtable-generic.c:290
locks held by syz.5.6154/25470: 2, last CPU#0:
#0: ffff8880354e9d38 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:600 [inline]
#0: ffff8880354e9d38 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x1a4/0x9f0 mm/mmap.c:1299
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x240 mm/pgtable-generic.c:290
=============================================
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 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 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 07/24/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409
Code: e8 2e de 54 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 ef e5 c4 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 da 64 75 06 cc 44 89 f9 80 e1 07
RSP: 0018:ffffc900001578b8 EFLAGS: 00000002
RAX: 1ffffffff35a7400 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff8572f400 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff9ad3a0c0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888124dd1000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000240 CR3: 0000000079868000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000800400 DR2: 0000000000000000
DR3: 0000000000000000 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+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