------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
migration/0/16 is trying to acquire lock:
ffffffff8d113a00 (console_owner){-.-.}-{0:0}, at: console_lock_spinning_enable+0x2c/0x60 kernel/printk/printk.c:1802

but task is already holding lock:
ffff8880b8e3a358 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x98/0x130 kernel/sched/core.c:483

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+0x2e/0x40 kernel/locking/spinlock.c:368
       raw_spin_rq_lock_nested+0x25/0x130 kernel/sched/core.c:475
       raw_spin_rq_lock kernel/sched/sched.h:1326 [inline]
       rq_lock kernel/sched/sched.h:1621 [inline]
       task_fork_fair+0x5c/0x360 kernel/sched/fair.c:11499
       sched_cgroup_fork+0x2e8/0x340 kernel/sched/core.c:4485
       copy_process+0x22f4/0x3e70 kernel/fork.c:2398
       kernel_clone+0x23f/0x990 kernel/fork.c:2682
       kernel_thread+0xfa/0x160 kernel/fork.c:2734
       rest_init+0x21/0x330 init/main.c:681
       start_kernel+0x489/0x540 init/main.c:1114
       secondary_startup_64_no_verify+0xb1/0xbb

-> #3 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
       try_to_wake_up+0x5a/0x1020 kernel/sched/core.c:4049
       __wake_up_common+0x28e/0x4d0 kernel/sched/wait.c:108
       __wake_up_common_lock kernel/sched/wait.c:138 [inline]
       __wake_up+0x10e/0x180 kernel/sched/wait.c:157
       tty_port_default_wakeup+0xa5/0xf0 drivers/tty/tty_port.c:51
       serial8250_tx_chars+0x615/0x800 drivers/tty/serial/8250/8250_port.c:1828
       serial8250_handle_irq+0x648/0x780 drivers/tty/serial/8250/8250_port.c:1931
       serial8250_default_handle_irq+0xb4/0x1a0 drivers/tty/serial/8250/8250_port.c:1948
       serial8250_interrupt+0x9b/0x1c0 drivers/tty/serial/8250/8250_core.c:127
       __handle_irq_event_percpu+0x299/0x9d0 kernel/irq/handle.c:156
       handle_irq_event_percpu kernel/irq/handle.c:196 [inline]
       handle_irq_event+0xa5/0x220 kernel/irq/handle.c:213
       handle_edge_irq+0x242/0xb20 kernel/irq/chip.c:819
       generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
       handle_irq arch/x86/kernel/irq.c:233 [inline]
       __common_interrupt+0xd7/0x1e0 arch/x86/kernel/irq.c:252
       common_interrupt+0x59/0xd0 arch/x86/kernel/irq.c:242
       asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:667

-> #2 (&tty->write_wait){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
       __wake_up_common_lock kernel/sched/wait.c:137 [inline]
       __wake_up+0xf4/0x180 kernel/sched/wait.c:157
       tty_port_default_wakeup+0xa5/0xf0 drivers/tty/tty_port.c:51
       serial8250_tx_chars+0x615/0x800 drivers/tty/serial/8250/8250_port.c:1828
       serial8250_handle_irq+0x648/0x780 drivers/tty/serial/8250/8250_port.c:1931
       serial8250_default_handle_irq+0xb4/0x1a0 drivers/tty/serial/8250/8250_port.c:1948
       serial8250_interrupt+0x9b/0x1c0 drivers/tty/serial/8250/8250_core.c:127
       __handle_irq_event_percpu+0x299/0x9d0 kernel/irq/handle.c:156
       handle_irq_event_percpu kernel/irq/handle.c:196 [inline]
       handle_irq_event+0xa5/0x220 kernel/irq/handle.c:213
       handle_edge_irq+0x242/0xb20 kernel/irq/chip.c:819
       generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
       handle_irq arch/x86/kernel/irq.c:233 [inline]
       __common_interrupt+0xd7/0x1e0 arch/x86/kernel/irq.c:252
       common_interrupt+0xb0/0xd0 arch/x86/kernel/irq.c:242
       asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:667
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
       _raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
       spin_unlock_irqrestore include/linux/spinlock.h:419 [inline]
       uart_write+0x62f/0x880 drivers/tty/serial/serial_core.c:592
       process_output_block drivers/tty/n_tty.c:592 [inline]
       n_tty_write+0xd19/0x1220 drivers/tty/n_tty.c:2339
       do_tty_write drivers/tty/tty_io.c:1038 [inline]
       file_tty_write+0x50c/0x8a0 drivers/tty/tty_io.c:1110
       call_write_iter include/linux/fs.h:2179 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x748/0xd70 fs/read_write.c:594
       ksys_write+0x153/0x260 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&port_lock_key){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
       serial8250_console_write+0x16c/0xf50 drivers/tty/serial/8250/8250_port.c:3375
       call_console_drivers kernel/printk/printk.c:-1 [inline]
       console_unlock+0xb47/0x10f0 kernel/printk/printk.c:2744
       vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
       _printk+0xda/0x130 kernel/printk/printk.c:2299
       register_console+0x693/0x970 kernel/printk/printk.c:3107
       univ8250_console_init+0x41/0x50 drivers/tty/serial/8250/8250_core.c:690
       console_init+0x177/0x5d0 kernel/printk/printk.c:3207
       start_kernel+0x2fc/0x540 init/main.c:1050
       secondary_startup_64_no_verify+0xb1/0xbb

-> #0 (console_owner){-.-.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3120 [inline]
       check_prevs_add kernel/locking/lockdep.c:3239 [inline]
       validate_chain kernel/locking/lockdep.c:3855 [inline]
       __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120
       lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
       console_lock_spinning_enable+0x51/0x60 kernel/printk/printk.c:1805
       console_unlock+0x8b5/0x10f0 kernel/printk/printk.c:2741
       vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
       _printk+0xda/0x130 kernel/printk/printk.c:2299
       report_bug+0x1e7/0x2e0 lib/bug.c:195
       handle_bug+0x3a/0x70 arch/x86/kernel/traps.c:239
       exc_invalid_op+0x16/0x40 arch/x86/kernel/traps.c:259
       asm_exc_invalid_op+0x16/0x20 arch/x86/include/asm/idtentry.h:604
       update_rq_clock+0x305/0x460 kernel/sched/core.c:687
       pick_next_task kernel/sched/core.c:5870 [inline]
       __schedule+0x26d9/0x4350 kernel/sched/core.c:6359
       schedule+0x11b/0x1e0 kernel/sched/core.c:6478
       smpboot_thread_fn+0x59d/0x990 kernel/smpboot.c:160
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

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 ***

2 locks held by migration/0/16:
 #0: ffff8880b8e3a358 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x98/0x130 kernel/sched/core.c:483
 #1: ffffffff8d113ae0 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0xa7/0x150 kernel/printk/printk.c:2273

stack backtrace:
CPU: 0 PID: 16 Comm: migration/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Stopper: 0x0 <- 0x0
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x400 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3120 [inline]
 check_prevs_add kernel/locking/lockdep.c:3239 [inline]
 validate_chain kernel/locking/lockdep.c:3855 [inline]
 __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120
 lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
 console_lock_spinning_enable+0x51/0x60 kernel/printk/printk.c:1805
 console_unlock+0x8b5/0x10f0 kernel/printk/printk.c:2741
 vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
 _printk+0xda/0x130 kernel/printk/printk.c:2299
 report_bug+0x1e7/0x2e0 lib/bug.c:195
 handle_bug+0x3a/0x70 arch/x86/kernel/traps.c:239
 exc_invalid_op+0x16/0x40 arch/x86/kernel/traps.c:259
 asm_exc_invalid_op+0x16/0x20 arch/x86/include/asm/idtentry.h:604
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1317 [inline]
RIP: 0010:update_rq_clock+0x305/0x460 kernel/sched/core.c:671
Code: 00 00 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 fd fe 6b 00 48 01 2b 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b e9 87 fd ff ff 48 89 df e8 4c c4 01 00 49 89 c6 48 81 c3 88
RSP: 0018:ffffc90000d57c20 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b8f3a340 RCX: ec1d654fcbba1300
RDX: 0000000000000000 RSI: ffffffff8a2b3e00 RDI: ffffffff8a7a4b40
RBP: ffffc90000d57e38 R08: ffff888023835007 R09: 1ffff11004706a00
R10: dffffc0000000000 R11: ffffed1004706a01 R12: 0000000000000001
R13: dffffc0000000000 R14: ffff8880b8f3b088 R15: ffff8880b8f00000
 pick_next_task kernel/sched/core.c:5870 [inline]
 __schedule+0x26d9/0x4350 kernel/sched/core.c:6359
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 smpboot_thread_fn+0x59d/0x990 kernel/smpboot.c:160
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
WARNING: CPU: 0 PID: 16 at kernel/sched/sched.h:1317 update_rq_clock+0x305/0x460 kernel/sched/core.c:687
Modules linked in:
CPU: 0 PID: 16 Comm: migration/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Stopper: 0x0 <- 0x0
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1317 [inline]
RIP: 0010:update_rq_clock+0x305/0x460 kernel/sched/core.c:671
Code: 00 00 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 fd fe 6b 00 48 01 2b 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b e9 87 fd ff ff 48 89 df e8 4c c4 01 00 49 89 c6 48 81 c3 88
RSP: 0018:ffffc90000d57c20 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b8f3a340 RCX: ec1d654fcbba1300
RDX: 0000000000000000 RSI: ffffffff8a2b3e00 RDI: ffffffff8a7a4b40
RBP: ffffc90000d57e38 R08: ffff888023835007 R09: 1ffff11004706a00
R10: dffffc0000000000 R11: ffffed1004706a01 R12: 0000000000000001
R13: dffffc0000000000 R14: ffff8880b8f3b088 R15: ffff8880b8f00000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000072fe5000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 pick_next_task kernel/sched/core.c:5870 [inline]
 __schedule+0x26d9/0x4350 kernel/sched/core.c:6359
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 smpboot_thread_fn+0x59d/0x990 kernel/smpboot.c:160
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>