------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.2.493/7999 is trying to acquire lock:
ffffffff8df35980 (console_owner){-.-.}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:2024 [inline]
ffffffff8df35980 (console_owner){-.-.}-{0:0}, at: vprintk_emit+0x321/0x5f0 kernel/printk/printk.c:2425

but task is already holding lock:
ffff8880b863a918 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:647

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #5 (&rq->__lock){-.-.}-{2:2}:
       _raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:639
       raw_spin_rq_lock kernel/sched/sched.h:1556 [inline]
       task_rq_lock+0xbc/0x470 kernel/sched/core.c:739
       cgroup_move_task+0x92/0x2a0 kernel/sched/psi.c:1170
       css_set_move_task+0x658/0x9e0 kernel/cgroup/cgroup.c:951
       cgroup_post_fork+0x1ef/0x7a0 kernel/cgroup/cgroup.c:6913
       copy_process+0x3614/0x3950 kernel/fork.c:2465
       kernel_clone+0x21e/0x820 kernel/fork.c:2651
       user_mode_thread+0xdd/0x140 kernel/fork.c:2727
       rest_init+0x23/0x300 init/main.c:722
       start_kernel+0x3a7/0x400 init/main.c:1206
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x147

-> #4 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:557 [inline]
       try_to_wake_up+0x67/0x12b0 kernel/sched/core.c:4108
       create_worker+0x503/0x720 kernel/workqueue.c:2847
       workqueue_init+0x3ea/0x690 kernel/workqueue.c:8025
       kernel_init_freeable+0x302/0x4b0 init/main.c:1673
       kernel_init+0x1d/0x1d0 init/main.c:1578
       ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #3 (&pool->lock){-.-.}-{2:2}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       __queue_work+0x7eb/0xf90 kernel/workqueue.c:-1
       queue_work_on+0x181/0x270 kernel/workqueue.c:2405
       queue_work include/linux/workqueue.h:669 [inline]
       rpm_suspend+0xe44/0x1700 drivers/base/power/runtime.c:688
       __pm_runtime_idle+0x12f/0x1a0 drivers/base/power/runtime.c:1129
       pm_runtime_put include/linux/pm_runtime.h:563 [inline]
       __device_attach+0x342/0x430 drivers/base/dd.c:1049
       device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1086
       bus_probe_device+0x12a/0x220 drivers/base/bus.c:574
       device_add+0x7b6/0xb80 drivers/base/core.c:3689
       serial_base_port_add+0x18f/0x260 drivers/tty/serial/serial_base_bus.c:183
       serial_core_port_device_add drivers/tty/serial/serial_core.c:3252 [inline]
       serial_core_register_port+0x369/0x2800 drivers/tty/serial/serial_core.c:3291
       serial8250_register_8250_port+0x1658/0x1fd0 drivers/tty/serial/8250/8250_core.c:822
       serial_pnp_probe+0x527/0x7d0 drivers/tty/serial/8250/8250_pnp.c:480
       pnp_device_probe+0x30b/0x4c0 drivers/pnp/driver.c:111
       call_driver_probe drivers/base/dd.c:-1 [inline]
       really_probe+0x26d/0xad0 drivers/base/dd.c:659
       __driver_probe_device+0x18c/0x320 drivers/base/dd.c:801
       driver_probe_device+0x4f/0x240 drivers/base/dd.c:831
       __driver_attach+0x349/0x650 drivers/base/dd.c:1225
       bus_for_each_dev+0x233/0x2b0 drivers/base/bus.c:383
       bus_add_driver+0x345/0x670 drivers/base/bus.c:715
       driver_register+0x23a/0x320 drivers/base/driver.c:249
       serial8250_init+0x8f/0x160 drivers/tty/serial/8250/8250_platform.c:317
       do_one_initcall+0x1fb/0x820 init/main.c:1378
       do_initcall_level+0x104/0x190 init/main.c:1440
       do_initcalls+0x59/0xa0 init/main.c:1456
       kernel_init_freeable+0x334/0x4b0 init/main.c:1688
       kernel_init+0x1d/0x1d0 init/main.c:1578
       ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #2 (&dev->power.lock){-.-.}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
       __pm_runtime_resume+0x10f/0x180 drivers/base/power/runtime.c:1196
       pm_runtime_get include/linux/pm_runtime.h:494 [inline]
       __uart_start+0x171/0x460 drivers/tty/serial/serial_core.c:149
       uart_write+0xdc/0x130 drivers/tty/serial/serial_core.c:633
       process_output_block drivers/tty/n_tty.c:557 [inline]
       n_tty_write+0xd78/0x12a0 drivers/tty/n_tty.c:2366
       iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
       file_tty_write+0x559/0xa20 drivers/tty/tty_io.c:1081
       new_sync_write fs/read_write.c:593 [inline]
       vfs_write+0x5c9/0xb30 fs/read_write.c:686
       ksys_write+0x145/0x250 fs/read_write.c:738
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&port_lock_key){-.-.}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
       uart_port_lock_irqsave include/linux/serial_core.h:717 [inline]
       serial8250_console_write+0x17e/0x1ba0 drivers/tty/serial/8250/8250_port.c:3301
       console_emit_next_record kernel/printk/printk.c:3129 [inline]
       console_flush_one_record kernel/printk/printk.c:3215 [inline]
       console_flush_all+0x745/0xb60 kernel/printk/printk.c:3289
       __console_flush_and_unlock kernel/printk/printk.c:3319 [inline]
       console_unlock+0xbb/0x190 kernel/printk/printk.c:3359
       vprintk_emit+0x4f8/0x5f0 kernel/printk/printk.c:2426
       _printk+0xcf/0x120 kernel/printk/printk.c:2451
       register_console+0xa8b/0xf90 kernel/printk/printk.c:4170
       univ8250_console_init+0x3a/0x70 drivers/tty/serial/8250/8250_core.c:515
       console_init+0xfc/0x3f0 kernel/printk/printk.c:4369
       start_kernel+0x24d/0x400 init/main.c:1143
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x147

-> #0 (console_owner){-.-.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868
       console_trylock_spinning kernel/printk/printk.c:2024 [inline]
       vprintk_emit+0x33d/0x5f0 kernel/printk/printk.c:2425
       _printk+0xcf/0x120 kernel/printk/printk.c:2451
       __report_bug+0x305/0x500 lib/bug.c:243
       report_bug+0x16a/0x220 lib/bug.c:281
       handle_bug+0x98/0x200 arch/x86/kernel/traps.c:435
       exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:489
       asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
       sched_change_end+0x4f6/0x640 kernel/sched/core.c:10851
       class_sched_change_destructor kernel/sched/sched.h:3956 [inline]
       rt_mutex_setprio+0x488/0xb70 kernel/sched/core.c:7331
       rt_mutex_adjust_prio kernel/locking/rtmutex.c:539 [inline]
       remove_waiter+0x7f5/0xaf0 kernel/locking/rtmutex.c:1567
       rt_mutex_cleanup_proxy_lock+0x6c/0x100 kernel/locking/rtmutex_api.c:458
       futex_lock_pi+0x530/0xa90 kernel/futex/pi.c:1067
       do_futex+0x292/0x420 kernel/futex/syscalls.c:146
       __do_sys_futex kernel/futex/syscalls.c:207 [inline]
       __se_sys_futex+0x36f/0x400 kernel/futex/syscalls.c:188
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  console_owner --> &p->pi_lock --> &rq->__lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&rq->__lock);
                               lock(&p->pi_lock);
                               lock(&rq->__lock);
  lock(console_owner);

 *** DEADLOCK ***

3 locks held by syz.2.493/7999:
 #0: ffff8880329e1e28 (&pi_futex_key){....}-{2:2}, at: rt_mutex_cleanup_proxy_lock+0x23/0x100 kernel/locking/rtmutex_api.c:440
 #1: ffff88802afca8e8 (&p->pi_lock){-.-.}-{2:2}, at: remove_waiter+0x286/0xaf0 kernel/locking/rtmutex.c:1560
 #2: ffff8880b863a918 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:647

stack backtrace:
CPU: 1 UID: 0 PID: 7999 Comm: syz.2.493 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868
 console_trylock_spinning kernel/printk/printk.c:2024 [inline]
 vprintk_emit+0x33d/0x5f0 kernel/printk/printk.c:2425
 _printk+0xcf/0x120 kernel/printk/printk.c:2451
 __report_bug+0x305/0x500 lib/bug.c:243
 report_bug+0x16a/0x220 lib/bug.c:281
 handle_bug+0x98/0x200 arch/x86/kernel/traps.c:435
 exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:489
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
RIP: 0010:sched_change_end+0x4f6/0x640 kernel/sched/core.c:10851
Code: 00 74 26 48 83 c4 38 5b 41 5c 41 5d 41 5e 41 5f 5d e9 be de cb 09 cc 90 0f 0b 90 e9 1d fc ff ff 90 0f 0b 90 e9 86 fc ff ff 90 <0f> 0b 90 eb d4 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 49 fb ff ff 48
RSP: 0018:ffffc90003757850 EFLAGS: 00010046
RAX: 1ffff110055f93d0 RBX: ffffffff8d9a4810 RCX: ffffffff8192ed2f
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff88802afc9e80
RBP: ffff88802afca128 R08: ffff88802afc9e87 R09: 1ffff110055f93d0
R10: dffffc0000000000 R11: ffffed10055f93d1 R12: dffffc0000000000
R13: ffff88802afc9e80 R14: ffff8880b873a900 R15: ffff88802afc9e80
 class_sched_change_destructor kernel/sched/sched.h:3956 [inline]
 rt_mutex_setprio+0x488/0xb70 kernel/sched/core.c:7331
 rt_mutex_adjust_prio kernel/locking/rtmutex.c:539 [inline]
 remove_waiter+0x7f5/0xaf0 kernel/locking/rtmutex.c:1567
 rt_mutex_cleanup_proxy_lock+0x6c/0x100 kernel/locking/rtmutex_api.c:458
 futex_lock_pi+0x530/0xa90 kernel/futex/pi.c:1067
 do_futex+0x292/0x420 kernel/futex/syscalls.c:146
 __do_sys_futex kernel/futex/syscalls.c:207 [inline]
 __se_sys_futex+0x36f/0x400 kernel/futex/syscalls.c:188
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f570d78f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f570e603038 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007f570d9e5fa0 RCX: 00007f570d78f749
RDX: 0000000000000002 RSI: 0000000000000086 RDI: 0000200000000180
RBP: 00007f570d813f91 R08: 0000000000000000 R09: 00000000fffffffc
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f570d9e6038 R14: 00007f570d9e5fa0 R15: 00007fff2e468728
 </TASK>
WARNING: kernel/sched/core.c:10852 at sched_change_end+0x4f6/0x640 kernel/sched/core.c:10851, CPU#1: syz.2.493/7999
Modules linked in:
CPU: 1 UID: 0 PID: 7999 Comm: syz.2.493 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:sched_change_end+0x4f6/0x640 kernel/sched/core.c:10851
Code: 00 74 26 48 83 c4 38 5b 41 5c 41 5d 41 5e 41 5f 5d e9 be de cb 09 cc 90 0f 0b 90 e9 1d fc ff ff 90 0f 0b 90 e9 86 fc ff ff 90 <0f> 0b 90 eb d4 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 49 fb ff ff 48
RSP: 0018:ffffc90003757850 EFLAGS: 00010046
RAX: 1ffff110055f93d0 RBX: ffffffff8d9a4810 RCX: ffffffff8192ed2f
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff88802afc9e80
RBP: ffff88802afca128 R08: ffff88802afc9e87 R09: 1ffff110055f93d0
R10: dffffc0000000000 R11: ffffed10055f93d1 R12: dffffc0000000000
R13: ffff88802afc9e80 R14: ffff8880b873a900 R15: ffff88802afc9e80
FS:  00007f570e6036c0(0000) GS:ffff888125f32000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000003f3000 CR3: 000000002f6fa000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 class_sched_change_destructor kernel/sched/sched.h:3956 [inline]
 rt_mutex_setprio+0x488/0xb70 kernel/sched/core.c:7331
 rt_mutex_adjust_prio kernel/locking/rtmutex.c:539 [inline]
 remove_waiter+0x7f5/0xaf0 kernel/locking/rtmutex.c:1567
 rt_mutex_cleanup_proxy_lock+0x6c/0x100 kernel/locking/rtmutex_api.c:458
 futex_lock_pi+0x530/0xa90 kernel/futex/pi.c:1067
 do_futex+0x292/0x420 kernel/futex/syscalls.c:146
 __do_sys_futex kernel/futex/syscalls.c:207 [inline]
 __se_sys_futex+0x36f/0x400 kernel/futex/syscalls.c:188
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f570d78f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f570e603038 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007f570d9e5fa0 RCX: 00007f570d78f749
RDX: 0000000000000002 RSI: 0000000000000086 RDI: 0000200000000180
RBP: 00007f570d813f91 R08: 0000000000000000 R09: 00000000fffffffc
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f570d9e6038 R14: 00007f570d9e5fa0 R15: 00007fff2e468728
 </TASK>