------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.109/6378 is trying to acquire lock:
ffffffff8e0d6440 (console_owner){....}-{0:0}, at: console_lock_spinning_enable+0x61/0x80 kernel/printk/printk.c:1897

but task is already holding lock:
ffff8880b843ab98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:647 [inline]
ffff8880b843ab98 (&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:1556 [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+0x288/0x5f0 kernel/cgroup/cgroup.c:948
       cgroup_post_fork+0x201/0x9e0 kernel/cgroup/cgroup.c:6908
       copy_process+0x51d3/0x74e0 kernel/fork.c:2423
       kernel_clone+0xfc/0x910 kernel/fork.c:2609
       user_mode_thread+0xc8/0x110 kernel/fork.c:2685
       rest_init+0x23/0x2b0 init/main.c:722
       start_kernel+0x3f6/0x4d0 init/main.c:1111
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x130/0x190 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+0xb7/0x1860 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+0x4d/0x60 drivers/tty/tty_port.c:67
       serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1719
       serial8250_handle_irq+0x761/0xcb0 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:82
       __handle_irq_event_percpu+0x236/0x890 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+0x3ca/0x9e0 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+0xd0/0x2f0 arch/x86/kernel/irq.c:326
       common_interrupt+0x61/0xe0 arch/x86/kernel/irq.c:319
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688

-> #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+0x4d/0x60 drivers/tty/tty_port.c:67
       serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1719
       serial8250_handle_irq+0x761/0xcb0 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:82
       __handle_irq_event_percpu+0x236/0x890 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+0x3ca/0x9e0 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+0xd0/0x2f0 arch/x86/kernel/irq.c:326
       common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:319
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
       _raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194
       spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
       uart_port_unlock_irqrestore include/linux/serial_core.h:788 [inline]
       uart_port_unlock_deref drivers/tty/serial/serial_core.c:91 [inline]
       uart_port_unlock_deref drivers/tty/serial/serial_core.c:88 [inline]
       uart_write+0x2a4/0xb30 drivers/tty/serial/serial_core.c:634
       process_output_block drivers/tty/n_tty.c:561 [inline]
       n_tty_write+0x41e/0x11e0 drivers/tty/n_tty.c:2377
       iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
       file_tty_write.constprop.0+0x503/0x9b0 drivers/tty/tty_io.c:1081
       tty_write drivers/tty/tty_io.c:1102 [inline]
       redirected_tty_write drivers/tty/tty_io.c:1125 [inline]
       redirected_tty_write+0xd4/0x120 drivers/tty/tty_io.c:1105
       new_sync_write fs/read_write.c:593 [inline]
       vfs_write+0x7d3/0x11d0 fs/read_write.c:686
       ksys_write+0x12a/0x250 fs/read_write.c:738
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/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+0x3a/0x60 kernel/locking/spinlock.c:162
       uart_port_lock_irqsave include/linux/serial_core.h:717 [inline]
       serial8250_console_write+0x181/0x1890 drivers/tty/serial/8250/8250_port.c:3301
       console_emit_next_record kernel/printk/printk.c:3111 [inline]
       console_flush_all+0x801/0xc60 kernel/printk/printk.c:3199
       __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
       console_unlock+0xd8/0x210 kernel/printk/printk.c:3298
       vprintk_emit+0x3d7/0x680 kernel/printk/printk.c:2423
       _printk+0xc7/0x100 kernel/printk/printk.c:2448
       register_console+0xc27/0x11b0 kernel/printk/printk.c:4099
       univ8250_console_init+0x5f/0x90 drivers/tty/serial/8250/8250_core.c:511
       console_init+0x152/0x600 kernel/printk/printk.c:4298
       start_kernel+0x29f/0x4d0 init/main.c:1048
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x130/0x190 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+0x1542/0x22f0 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825
       console_lock_spinning_enable+0x72/0x80 kernel/printk/printk.c:1897
       console_emit_next_record kernel/printk/printk.c:3105 [inline]
       console_flush_all+0x7aa/0xc60 kernel/printk/printk.c:3199
       __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
       console_unlock+0xd8/0x210 kernel/printk/printk.c:3298
       vprintk_emit+0x3d7/0x680 kernel/printk/printk.c:2423
       _printk+0xc7/0x100 kernel/printk/printk.c:2448
       __report_bug+0x3a6/0x520 lib/bug.c:239
       report_bug+0xb2/0x220 lib/bug.c:277
       handle_bug+0x127/0x260 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:1547 [inline]
       lockdep_assert_rq_held kernel/sched/sched.h:1545 [inline]
       update_rq_clock+0x34a/0xc70 kernel/sched/core.c:837
       pick_next_task kernel/sched/core.c:6080 [inline]
       __schedule+0x212d/0x6150 kernel/sched/core.c:6797
       __schedule_loop kernel/sched/core.c:6937 [inline]
       schedule+0xe7/0x3a0 kernel/sched/core.c:6952
       do_nanosleep+0x219/0x580 kernel/time/hrtimer.c:2116
       hrtimer_nanosleep+0x155/0x380 kernel/time/hrtimer.c:2163
       common_nsleep+0xa1/0xd0 kernel/time/posix-timers.c:1352
       __do_sys_clock_nanosleep kernel/time/posix-timers.c:1398 [inline]
       __se_sys_clock_nanosleep kernel/time/posix-timers.c:1375 [inline]
       __x64_sys_clock_nanosleep+0x34d/0x4a0 kernel/time/posix-timers.c:1375
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/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.2.109/6378:
 #0: ffff8880b843ab98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:647 [inline]
 #0: ffff8880b843ab98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:632
 #1: ffffffff8e1b6880 (console_lock){+.+.}-{0:0}, at: _printk+0xc7/0x100 kernel/printk/printk.c:2448
 #2: ffffffff8e1b68f0 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
 #2: ffffffff8e1b68f0 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:335 [inline]
 #2: ffffffff8e1b68f0 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:289 [inline]
 #2: ffffffff8e1b68f0 (console_srcu){....}-{0:0}, at: console_flush_all+0x158/0xc60 kernel/printk/printk.c:3176

stack backtrace:
CPU: 0 UID: 0 PID: 6378 Comm: syz.2.109 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x2db/0x410 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+0x1542/0x22f0 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825
 console_lock_spinning_enable+0x72/0x80 kernel/printk/printk.c:1897
 console_emit_next_record kernel/printk/printk.c:3105 [inline]
 console_flush_all+0x7aa/0xc60 kernel/printk/printk.c:3199
 __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
 console_unlock+0xd8/0x210 kernel/printk/printk.c:3298
 vprintk_emit+0x3d7/0x680 kernel/printk/printk.c:2423
 _printk+0xc7/0x100 kernel/printk/printk.c:2448
 __report_bug+0x3a6/0x520 lib/bug.c:239
 report_bug+0xb2/0x220 lib/bug.c:277
 handle_bug+0x127/0x260 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:1547 [inline]
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1545 [inline]
RIP: 0010:update_rq_clock+0x34a/0xc70 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 c3 cc cc cc cc a8 04 0f 84 9c fd ff ff 90 0f 0b 90 e9 93 fd ff ff 90 <0f> 0b 90 e9 4f fd ff ff 48 8d bb 18 0e 00 00 48 b8 00 00 00 00 00
RSP: 0018:ffffc9000410fa90 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b853ab80 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff8d87a111 RDI: ffffffff8bd1d700
RBP: 0000000000000001 R08: ffff8880b843b688 R09: fffffbfff20cc09a
R10: ffffffff906604d7 R11: 0000000000000001 R12: ffffffff90663534
R13: ffffffff8db376a0 R14: ffff88802adc9e80 R15: ffff8880b853ab80
 pick_next_task kernel/sched/core.c:6080 [inline]
 __schedule+0x212d/0x6150 kernel/sched/core.c:6797
 __schedule_loop kernel/sched/core.c:6937 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6952
 do_nanosleep+0x219/0x580 kernel/time/hrtimer.c:2116
 hrtimer_nanosleep+0x155/0x380 kernel/time/hrtimer.c:2163
 common_nsleep+0xa1/0xd0 kernel/time/posix-timers.c:1352
 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1398 [inline]
 __se_sys_clock_nanosleep kernel/time/posix-timers.c:1375 [inline]
 __x64_sys_clock_nanosleep+0x34d/0x4a0 kernel/time/posix-timers.c:1375
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd9ca5c2085
Code: 24 0c 89 3c 24 48 89 4c 24 18 e8 f6 54 ff ff 4c 8b 54 24 18 48 8b 54 24 10 41 89 c0 8b 74 24 0c 8b 3c 24 b8 e6 00 00 00 0f 05 <44> 89 c7 48 89 04 24 e8 4f 55 ff ff 48 8b 04 24 48 83 c4 28 f7 d8
RSP: 002b:00007ffc2bd1e400 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 00007fd9ca7e5fa0 RCX: 00007fd9ca5c2085
RDX: 00007ffc2bd1e440 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd9ca7e7da0 R08: 0000000000000000 R09: 00007fd9cb363000
R10: 0000000000000000 R11: 0000000000000293 R12: 000000000001c59e
R13: 00007fd9ca7e6180 R14: ffffffffffffffff R15: 00007ffc2bd1e580
 </TASK>
WARNING: kernel/sched/sched.h:1547 at lockdep_assert_rq_held kernel/sched/sched.h:1547 [inline], CPU#0: syz.2.109/6378
WARNING: kernel/sched/sched.h:1547 at lockdep_assert_rq_held kernel/sched/sched.h:1545 [inline], CPU#0: syz.2.109/6378
WARNING: kernel/sched/sched.h:1547 at update_rq_clock+0x34a/0xc70 kernel/sched/core.c:837, CPU#0: syz.2.109/6378
Modules linked in:
CPU: 0 UID: 0 PID: 6378 Comm: syz.2.109 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1547 [inline]
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1545 [inline]
RIP: 0010:update_rq_clock+0x34a/0xc70 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 c3 cc cc cc cc a8 04 0f 84 9c fd ff ff 90 0f 0b 90 e9 93 fd ff ff 90 <0f> 0b 90 e9 4f fd ff ff 48 8d bb 18 0e 00 00 48 b8 00 00 00 00 00
RSP: 0018:ffffc9000410fa90 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b853ab80 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff8d87a111 RDI: ffffffff8bd1d700
RBP: 0000000000000001 R08: ffff8880b843b688 R09: fffffbfff20cc09a
R10: ffffffff906604d7 R11: 0000000000000001 R12: ffffffff90663534
R13: ffffffff8db376a0 R14: ffff88802adc9e80 R15: ffff8880b853ab80
FS:  000055558ca4b500(0000) GS:ffff888124ba3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30d63fff CR3: 00000000256d0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 pick_next_task kernel/sched/core.c:6080 [inline]
 __schedule+0x212d/0x6150 kernel/sched/core.c:6797
 __schedule_loop kernel/sched/core.c:6937 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6952
 do_nanosleep+0x219/0x580 kernel/time/hrtimer.c:2116
 hrtimer_nanosleep+0x155/0x380 kernel/time/hrtimer.c:2163
 common_nsleep+0xa1/0xd0 kernel/time/posix-timers.c:1352
 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1398 [inline]
 __se_sys_clock_nanosleep kernel/time/posix-timers.c:1375 [inline]
 __x64_sys_clock_nanosleep+0x34d/0x4a0 kernel/time/posix-timers.c:1375
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd9ca5c2085
Code: 24 0c 89 3c 24 48 89 4c 24 18 e8 f6 54 ff ff 4c 8b 54 24 18 48 8b 54 24 10 41 89 c0 8b 74 24 0c 8b 3c 24 b8 e6 00 00 00 0f 05 <44> 89 c7 48 89 04 24 e8 4f 55 ff ff 48 8b 04 24 48 83 c4 28 f7 d8
RSP: 002b:00007ffc2bd1e400 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 00007fd9ca7e5fa0 RCX: 00007fd9ca5c2085
RDX: 00007ffc2bd1e440 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd9ca7e7da0 R08: 0000000000000000 R09: 00007fd9cb363000
R10: 0000000000000000 R11: 0000000000000293 R12: 000000000001c59e
R13: 00007fd9ca7e6180 R14: ffffffffffffffff R15: 00007ffc2bd1e580
 </TASK>