------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G          I  L     
------------------------------------------------------
syz.1.4181/28309 is trying to acquire lock:
ffffffff8e4eeee0 (console_owner){-.-.}-{0:0}, at: console_lock_spinning_enable+0x61/0x80 kernel/printk/printk.c:1900

but task is already holding lock:
ffff8880b843add8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:647 [inline]
ffff8880b843add8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:632

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&rq->__lock){-.-.}-{2:2}:
       _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:639
       raw_spin_rq_lock kernel/sched/sched.h:1580 [inline]
       task_rq_lock+0xcf/0x490 kernel/sched/core.c:739
       cgroup_move_task+0x81/0x2a0 kernel/sched/psi.c:1170
       css_set_move_task+0x285/0x600 kernel/cgroup/cgroup.c:948
       cgroup_post_fork+0x1fe/0x9b0 kernel/cgroup/cgroup.c:6910
       copy_process+0x57b0/0x7890 kernel/fork.c:2465
       kernel_clone+0xfc/0x930 kernel/fork.c:2651
       user_mode_thread+0xcc/0x110 kernel/fork.c:2727
       rest_init+0x21/0x260 init/main.c:722
       start_kernel+0x47a/0x480 init/main.c:1206
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x122/0x130 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x148

-> #3 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:557 [inline]
       try_to_wake_up+0xb2/0x1a60 kernel/sched/core.c:4106
       __wake_up_common+0x135/0x1f0 kernel/sched/wait.c:108
       __wake_up_common_lock kernel/sched/wait.c:125 [inline]
       __wake_up+0x31/0x60 kernel/sched/wait.c:146
       tty_port_default_wakeup+0x47/0x60 drivers/tty/tty_port.c:67
       serial8250_tx_chars+0x68f/0x860 drivers/tty/serial/8250/8250_port.c:1719
       serial8250_handle_irq+0x73e/0xcb0 drivers/tty/serial/8250/8250_port.c:1827
       serial8250_default_handle_irq+0x9e/0x270 drivers/tty/serial/8250/8250_port.c:1846
       serial8250_interrupt+0xf8/0x1d0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x232/0x800 kernel/irq/handle.c:211
       handle_irq_event_percpu kernel/irq/handle.c:248 [inline]
       handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:265
       handle_edge_irq+0x375/0x970 kernel/irq/chip.c:855
       generic_handle_irq_desc include/linux/irqdesc.h:172 [inline]
       handle_irq arch/x86/kernel/irq.c:255 [inline]
       call_irq_handler arch/x86/kernel/irq.c:311 [inline]
       __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:326
       common_interrupt+0xb9/0xe0 arch/x86/kernel/irq.c:319
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688
       finish_task_switch.isra.0+0x20d/0xb70 kernel/sched/core.c:5118
       context_switch kernel/sched/core.c:5263 [inline]
       __schedule+0xfec/0x5e10 kernel/sched/core.c:6867
       __schedule_loop kernel/sched/core.c:6949 [inline]
       schedule+0xdd/0x390 kernel/sched/core.c:6964
       schedule_hrtimeout_range_clock+0x2d8/0x320 kernel/time/sleep_timeout.c:207
       poll_schedule_timeout.constprop.0+0xbe/0x1b0 fs/select.c:241
       do_poll fs/select.c:954 [inline]
       do_sys_poll+0x9ab/0xeb0 fs/select.c:1005
       __do_sys_ppoll fs/select.c:1111 [inline]
       __se_sys_ppoll fs/select.c:1091 [inline]
       __x64_sys_ppoll+0x2b5/0x350 fs/select.c:1091
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&tty->write_wait){-...}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       __wake_up_common_lock kernel/sched/wait.c:124 [inline]
       __wake_up+0x1c/0x60 kernel/sched/wait.c:146
       tty_port_default_wakeup+0x47/0x60 drivers/tty/tty_port.c:67
       serial8250_tx_chars+0x68f/0x860 drivers/tty/serial/8250/8250_port.c:1719
       serial8250_handle_irq+0x73e/0xcb0 drivers/tty/serial/8250/8250_port.c:1827
       serial8250_default_handle_irq+0x9e/0x270 drivers/tty/serial/8250/8250_port.c:1846
       serial8250_interrupt+0xf8/0x1d0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x232/0x800 kernel/irq/handle.c:211
       handle_irq_event_percpu kernel/irq/handle.c:248 [inline]
       handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:265
       handle_edge_irq+0x375/0x970 kernel/irq/chip.c:855
       generic_handle_irq_desc include/linux/irqdesc.h:172 [inline]
       handle_irq arch/x86/kernel/irq.c:255 [inline]
       call_irq_handler arch/x86/kernel/irq.c:311 [inline]
       __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:326
       common_interrupt+0xb9/0xe0 arch/x86/kernel/irq.c:319
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688
       native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
       pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:81
       arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
       default_idle+0x9/0x10 arch/x86/kernel/process.c:767
       default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
       cpuidle_idle_call kernel/sched/idle.c:191 [inline]
       do_idle+0x35b/0x4b0 kernel/sched/idle.c:332
       cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:430
       rest_init+0x251/0x260 init/main.c:757
       start_kernel+0x47a/0x480 init/main.c:1206
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x122/0x130 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x148

-> #1 (&port_lock_key){-.-.}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       uart_port_lock_irqsave include/linux/serial_core.h:717 [inline]
       serial8250_console_write+0x17e/0x1900 drivers/tty/serial/8250/8250_port.c:3301
       console_emit_next_record kernel/printk/printk.c:3129 [inline]
       console_flush_one_record+0x790/0xe50 kernel/printk/printk.c:3215
       console_flush_all kernel/printk/printk.c:3289 [inline]
       __console_flush_and_unlock kernel/printk/printk.c:3319 [inline]
       console_unlock+0x103/0x260 kernel/printk/printk.c:3359
       vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2426
       _printk+0xcf/0x110 kernel/printk/printk.c:2451
       register_console.cold+0xc0/0x248 kernel/printk/printk.c:4170
       univ8250_console_init+0x6f/0x80 drivers/tty/serial/8250/8250_core.c:515
       console_init+0x371/0x520 kernel/printk/printk.c:4369
       start_kernel+0x300/0x480 init/main.c:1143
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x122/0x130 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x148

-> #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+0x14b8/0x2630 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x17c/0x330 kernel/locking/lockdep.c:5825
       console_lock_spinning_enable+0x72/0x80 kernel/printk/printk.c:1900
       console_emit_next_record kernel/printk/printk.c:3123 [inline]
       console_flush_one_record+0x739/0xe50 kernel/printk/printk.c:3215
       console_flush_all kernel/printk/printk.c:3289 [inline]
       __console_flush_and_unlock kernel/printk/printk.c:3319 [inline]
       console_unlock+0x103/0x260 kernel/printk/printk.c:3359
       vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2426
       _printk+0xcf/0x110 kernel/printk/printk.c:2451
       __report_bug.cold+0x15/0x137 lib/bug.c:243
       report_bug+0xb2/0x220 lib/bug.c:281
       handle_bug+0x166/0x2a0 arch/x86/kernel/traps.c:435
       exc_invalid_op+0x17/0x50 arch/x86/kernel/traps.c:489
       asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
       lockdep_assert_rq_held kernel/sched/sched.h:1571 [inline]
       lockdep_assert_rq_held kernel/sched/sched.h:1569 [inline]
       update_rq_clock+0x34a/0xd30 kernel/sched/core.c:837
       pick_next_task kernel/sched/core.c:6092 [inline]
       __schedule+0x1b0d/0x5e10 kernel/sched/core.c:6809
       __schedule_loop kernel/sched/core.c:6949 [inline]
       schedule+0xdd/0x390 kernel/sched/core.c:6964
       __exit_to_user_mode_loop kernel/entry/common.c:32 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:75 [inline]
       __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
       irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
       irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
       irqentry_exit+0x197/0x670 kernel/entry/common.c:196
       asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

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.1.4181/28309:
 #0: ffff8880b843add8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:647 [inline]
 #0: ffff8880b843add8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:632
 #1: ffffffff8e5cf320 (console_lock){+.+.}-{0:0}, at: _printk+0xcf/0x110 kernel/printk/printk.c:2451
 #2: ffffffff8e5cf398 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
 #2: ffffffff8e5cf398 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:409 [inline]
 #2: ffffffff8e5cf398 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:289 [inline]
 #2: ffffffff8e5cf398 (console_srcu){....}-{0:0}, at: console_flush_one_record+0xfd/0xe50 kernel/printk/printk.c:3192

stack backtrace:
CPU: 0 UID: 0 PID: 28309 Comm: syz.1.4181 Tainted: G          I  L      syzkaller #0 PREEMPT(full) 
Tainted: [I]=FIRMWARE_WORKAROUND, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043
 check_noncircular+0x146/0x160 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x17c/0x330 kernel/locking/lockdep.c:5825
 console_lock_spinning_enable+0x72/0x80 kernel/printk/printk.c:1900
 console_emit_next_record kernel/printk/printk.c:3123 [inline]
 console_flush_one_record+0x739/0xe50 kernel/printk/printk.c:3215
 console_flush_all kernel/printk/printk.c:3289 [inline]
 __console_flush_and_unlock kernel/printk/printk.c:3319 [inline]
 console_unlock+0x103/0x260 kernel/printk/printk.c:3359
 vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2426
 _printk+0xcf/0x110 kernel/printk/printk.c:2451
 __report_bug.cold+0x15/0x137 lib/bug.c:243
 report_bug+0xb2/0x220 lib/bug.c:281
 handle_bug+0x166/0x2a0 arch/x86/kernel/traps.c:435
 exc_invalid_op+0x17/0x50 arch/x86/kernel/traps.c:489
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1571 [inline]
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1569 [inline]
RIP: 0010:update_rq_clock+0x34a/0xd30 kernel/sched/core.c:837
Code: ab 48 0b 00 00 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e 41 5f e9 c8 eb a2 09 a8 04 0f 84 9e fd ff ff 90 0f 0b 90 e9 95 fd ff ff 90 <0f> 0b 90 e9 51 fd ff ff 48 8d bb 18 0e 00 00 48 b8 00 00 00 00 00
RSP: 0000:ffffc90004ca7d38 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b853adc0 RCX: 0000000000000001
RDX: 0000000000000046 RSI: ffffffff8dc1b45f RDI: ffffffff8bfa32a0
RBP: ffffc90004ca7ee0 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff90b771d7 R11: 0000000000000000 R12: ffffffff90b7a254
R13: ffff8880b853bbf0 R14: ffff88801e283d00 R15: ffff8880b853adc0
 pick_next_task kernel/sched/core.c:6092 [inline]
 __schedule+0x1b0d/0x5e10 kernel/sched/core.c:6809
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:6964
 __exit_to_user_mode_loop kernel/entry/common.c:32 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:75 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
 irqentry_exit+0x197/0x670 kernel/entry/common.c:196
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0033:0x7f8db846f40c
Code: c1 89 3a 00 00 49 89 d6 48 89 d3 74 28 25 ff 0f 00 00 83 f0 3d 8d 04 c0 89 c3 c1 eb 04 31 c3 69 db 2d eb d4 27 89 d8 c1 e8 0f <31> c3 81 e3 ff 0f 00 00 48 31 d3 80 3d 2a 2c 3a 00 00 0f 84 1c 01
RSP: 002b:00007ffd94cf22b0 EFLAGS: 00000a06
RAX: 0000000000013112 RBX: 0000000098893f2c RCX: ffffffff826739f6
RDX: ffffffff82673aa7 RSI: ffffffff826739f6 RDI: 00007f8db5ff4008
RBP: 00000000000008da R08: 00007f8db8800000 R09: 00007f8db8802000
R10: 00000000826739fa R11: 000000000000001a R12: 00007f8db88163f8
R13: 000000000006e15b R14: ffffffff82673aa7 R15: 00007f8db9345720
 </TASK>
debug_locks && !(lock_is_held(&(__rq_lockp(rq))->dep_map) != 0)
WARNING: kernel/sched/sched.h:1571 at lockdep_assert_rq_held kernel/sched/sched.h:1571 [inline], CPU#0: syz.1.4181/28309
WARNING: kernel/sched/sched.h:1571 at lockdep_assert_rq_held kernel/sched/sched.h:1569 [inline], CPU#0: syz.1.4181/28309
WARNING: kernel/sched/sched.h:1571 at update_rq_clock+0x34a/0xd30 kernel/sched/core.c:837, CPU#0: syz.1.4181/28309
Modules linked in:
CPU: 0 UID: 0 PID: 28309 Comm: syz.1.4181 Tainted: G          I  L      syzkaller #0 PREEMPT(full) 
Tainted: [I]=FIRMWARE_WORKAROUND, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1571 [inline]
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1569 [inline]
RIP: 0010:update_rq_clock+0x34a/0xd30 kernel/sched/core.c:837
Code: ab 48 0b 00 00 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e 41 5f e9 c8 eb a2 09 a8 04 0f 84 9e fd ff ff 90 0f 0b 90 e9 95 fd ff ff 90 <0f> 0b 90 e9 51 fd ff ff 48 8d bb 18 0e 00 00 48 b8 00 00 00 00 00
RSP: 0000:ffffc90004ca7d38 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b853adc0 RCX: 0000000000000001
RDX: 0000000000000046 RSI: ffffffff8dc1b45f RDI: ffffffff8bfa32a0
RBP: ffffc90004ca7ee0 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff90b771d7 R11: 0000000000000000 R12: ffffffff90b7a254
R13: ffff8880b853bbf0 R14: ffff88801e283d00 R15: ffff8880b853adc0
FS:  00005555579f4500(0000) GS:ffff8881245e3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555f6ca39d8 CR3: 000000007d0b2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 pick_next_task kernel/sched/core.c:6092 [inline]
 __schedule+0x1b0d/0x5e10 kernel/sched/core.c:6809
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:6964
 __exit_to_user_mode_loop kernel/entry/common.c:32 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:75 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
 irqentry_exit+0x197/0x670 kernel/entry/common.c:196
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0033:0x7f8db846f40c
Code: c1 89 3a 00 00 49 89 d6 48 89 d3 74 28 25 ff 0f 00 00 83 f0 3d 8d 04 c0 89 c3 c1 eb 04 31 c3 69 db 2d eb d4 27 89 d8 c1 e8 0f <31> c3 81 e3 ff 0f 00 00 48 31 d3 80 3d 2a 2c 3a 00 00 0f 84 1c 01
RSP: 002b:00007ffd94cf22b0 EFLAGS: 00000a06
RAX: 0000000000013112 RBX: 0000000098893f2c RCX: ffffffff826739f6
RDX: ffffffff82673aa7 RSI: ffffffff826739f6 RDI: 00007f8db5ff4008
RBP: 00000000000008da R08: 00007f8db8800000 R09: 00007f8db8802000
R10: 00000000826739fa R11: 000000000000001a R12: 00007f8db88163f8
R13: 000000000006e15b R14: ffffffff82673aa7 R15: 00007f8db9345720
 </TASK>