------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
migration/0/19 is trying to acquire lock:
ffffffff8e6f3880 (console_owner){-...}-{0:0}, at: console_lock_spinning_enable+0x61/0x80 kernel/printk/printk.c:1902

but task is already holding lock:
ffff8880b843b360 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:655 [inline]
ffff8880b843b360 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:639

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+0x2c/0x140 kernel/sched/core.c:647
       raw_spin_rq_lock kernel/sched/sched.h:1615 [inline]
       _task_rq_lock+0xcf/0x490 kernel/sched/core.c:747
       cgroup_move_task+0x81/0x2b0 kernel/sched/psi.c:1170
       css_set_move_task+0x285/0x600 kernel/cgroup/cgroup.c:948
       cgroup_post_fork+0x202/0x9b0 kernel/cgroup/cgroup.c:6917
       copy_process+0x5717/0x7a40 kernel/fork.c:2467
       kernel_clone+0xfc/0x9a0 kernel/fork.c:2653
       user_mode_thread+0xcc/0x110 kernel/fork.c:2729
       rest_init+0x21/0x260 init/main.c:725
       start_kernel+0x47f/0x480 init/main.c:1210
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x12b/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:132 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:570 [inline]
       try_to_wake_up+0xb2/0x1a80 kernel/sched/core.c:4130
       __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:1721
       serial8250_handle_irq_locked+0x5e6/0x7e0 drivers/tty/serial/8250/8250_port.c:1825
       serial8250_handle_irq.part.0+0xb8/0x550 drivers/tty/serial/8250/8250_port.c:1841
       serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1837 [inline]
       serial8250_default_handle_irq+0xc2/0x2a0 drivers/tty/serial/8250/8250_port.c:1855
       serial8250_interrupt+0xf8/0x1d0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x232/0x8e0 kernel/irq/handle.c:209
       handle_irq_event_percpu kernel/irq/handle.c:246 [inline]
       handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:263
       handle_edge_irq+0x375/0x970 kernel/irq/chip.c:855
       generic_handle_irq_desc include/linux/irqdesc.h:186 [inline]
       handle_irq arch/x86/kernel/irq.c:262 [inline]
       call_irq_handler arch/x86/kernel/irq.c:318 [inline]
       __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:333
       common_interrupt+0x60/0xe0 arch/x86/kernel/irq.c:326
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688
       variable_ffs arch/x86/include/asm/bitops.h:312 [inline]
       handle_softirqs+0x1af/0x9e0 kernel/softirq.c:610
       __do_softirq kernel/softirq.c:656 [inline]
       invoke_softirq kernel/softirq.c:496 [inline]
       __irq_exit_rcu+0xef/0x150 kernel/softirq.c:723
       irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
       instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
       sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1056
       asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
       arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline]
       raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline]
       rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
       rcu_is_watching+0x60/0xc0 kernel/rcu/tree.c:752
       trace_lock_acquire include/trace/events/lock.h:24 [inline]
       lock_acquire+0x317/0x380 kernel/locking/lockdep.c:5831
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776
       seq_read_iter+0xe1/0x1270 fs/seq_file.c:183
       kernfs_fop_read_iter+0x46c/0x610 fs/kernfs/file.c:297
       new_sync_read fs/read_write.c:493 [inline]
       vfs_read+0x825/0xb30 fs/read_write.c:574
       ksys_read+0x12a/0x250 fs/read_write.c:717
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 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:132 [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:1721
       serial8250_handle_irq_locked+0x5e6/0x7e0 drivers/tty/serial/8250/8250_port.c:1825
       serial8250_handle_irq.part.0+0xb8/0x550 drivers/tty/serial/8250/8250_port.c:1841
       serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1837 [inline]
       serial8250_default_handle_irq+0xc2/0x2a0 drivers/tty/serial/8250/8250_port.c:1855
       serial8250_interrupt+0xf8/0x1d0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x232/0x8e0 kernel/irq/handle.c:209
       handle_irq_event_percpu kernel/irq/handle.c:246 [inline]
       handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:263
       handle_edge_irq+0x375/0x970 kernel/irq/chip.c:855
       generic_handle_irq_desc include/linux/irqdesc.h:186 [inline]
       handle_irq arch/x86/kernel/irq.c:262 [inline]
       call_irq_handler arch/x86/kernel/irq.c:318 [inline]
       __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:333
       common_interrupt+0xb9/0xe0 arch/x86/kernel/irq.c:326
       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:62
       arch_safe_halt arch/x86/include/asm/paravirt.h:73 [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:199 [inline]
       do_idle+0x464/0x590 kernel/sched/idle.c:352
       cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:451
       rest_init+0x251/0x260 init/main.c:760
       start_kernel+0x47f/0x480 init/main.c:1210
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x12b/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:132 [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:3316
       console_emit_next_record kernel/printk/printk.c:3183 [inline]
       console_flush_one_record+0x790/0xe50 kernel/printk/printk.c:3269
       console_flush_all kernel/printk/printk.c:3343 [inline]
       __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
       console_unlock+0x103/0x260 kernel/printk/printk.c:3413
       vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479
       _printk+0xcf/0x110 kernel/printk/printk.c:2504
       register_console.cold+0xc0/0x248 kernel/printk/printk.c:4208
       univ8250_console_init+0x6f/0x80 drivers/tty/serial/8250/8250_core.c:515
       console_init+0x423/0x620 kernel/printk/printk.c:4407
       start_kernel+0x305/0x480 init/main.c:1147
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x12b/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+0x1cf/0x380 kernel/locking/lockdep.c:5825
       console_lock_spinning_enable+0x72/0x80 kernel/printk/printk.c:1902
       console_emit_next_record kernel/printk/printk.c:3177 [inline]
       console_flush_one_record+0x739/0xe50 kernel/printk/printk.c:3269
       console_flush_all kernel/printk/printk.c:3343 [inline]
       __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
       console_unlock+0x103/0x260 kernel/printk/printk.c:3413
       vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479
       _printk+0xcf/0x110 kernel/printk/printk.c:2504
       __report_bug.cold+0x15/0x137 lib/bug.c:243
       report_bug+0xb2/0x220 lib/bug.c:281
       handle_bug+0x16a/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:1600 [inline]
       lockdep_assert_rq_held kernel/sched/sched.h:1597 [inline]
       update_rq_clock+0x40a/0xd20 kernel/sched/core.c:850
       pick_next_task kernel/sched/core.c:6132 [inline]
       __schedule+0x1b7d/0x6120 kernel/sched/core.c:6852
       __schedule_loop kernel/sched/core.c:6993 [inline]
       schedule+0xdd/0x390 kernel/sched/core.c:7008
       smpboot_thread_fn+0x893/0xaa0 kernel/smpboot.c:156
       kthread+0x370/0x450 kernel/kthread.c:436
       ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

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 migration/0/19:
 #0: ffff8880b843b360 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:655 [inline]
 #0: ffff8880b843b360 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:639
 #1: ffffffff8e7d3cc0 (console_lock){+.+.}-{0:0}, at: _printk+0xcf/0x110 kernel/printk/printk.c:2504
 #2: ffffffff8e7d3d38 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:317 [inline]
 #2: ffffffff8e7d3d38 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline]
 #2: ffffffff8e7d3d38 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline]
 #2: ffffffff8e7d3d38 (console_srcu){....}-{0:0}, at: console_flush_one_record+0xfd/0xe50 kernel/printk/printk.c:3246

stack backtrace:
CPU: 0 UID: 0 PID: 19 Comm: migration/0 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Stopper: 0x0 <- 0x0
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+0x1cf/0x380 kernel/locking/lockdep.c:5825
 console_lock_spinning_enable+0x72/0x80 kernel/printk/printk.c:1902
 console_emit_next_record kernel/printk/printk.c:3177 [inline]
 console_flush_one_record+0x739/0xe50 kernel/printk/printk.c:3269
 console_flush_all kernel/printk/printk.c:3343 [inline]
 __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
 console_unlock+0x103/0x260 kernel/printk/printk.c:3413
 vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479
 _printk+0xcf/0x110 kernel/printk/printk.c:2504
 __report_bug.cold+0x15/0x137 lib/bug.c:243
 report_bug+0xb2/0x220 lib/bug.c:281
 handle_bug+0x16a/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:1600 [inline]
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1597 [inline]
RIP: 0010:update_rq_clock+0x40a/0xd20 kernel/sched/core.c:850
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 df fc ff ff 90 0f 0b 90 e9 d6 fc ff ff 90 <0f> 0b 90 e9 92 fc ff ff 4c 8d 83 40 0b 00 00 48 b8 00 00 00 00 00
RSP: 0018:ffffc90000187c28 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b853b300 RCX: 0000000000000001
RDX: 0000000000000046 RSI: ffffffff8de5b9eb RDI: ffffffff8c1b1420
RBP: ffffc90000187dd0 R08: 0000000000000001 R09: 0000000000000001
R10: ffff888021b81007 R11: 0000004423c45800 R12: ffffffff90da16e4
R13: ffff8880b853c140 R14: ffff8880341b5b80 R15: ffff8880b853b300
 pick_next_task kernel/sched/core.c:6132 [inline]
 __schedule+0x1b7d/0x6120 kernel/sched/core.c:6852
 __schedule_loop kernel/sched/core.c:6993 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7008
 smpboot_thread_fn+0x893/0xaa0 kernel/smpboot.c:156
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
debug_locks && !(lock_is_held(&(__rq_lockp(rq))->dep_map) != 0)
WARNING: kernel/sched/sched.h:1600 at lockdep_assert_rq_held kernel/sched/sched.h:1600 [inline], CPU#0: migration/0/19
WARNING: kernel/sched/sched.h:1600 at lockdep_assert_rq_held kernel/sched/sched.h:1597 [inline], CPU#0: migration/0/19
WARNING: kernel/sched/sched.h:1600 at update_rq_clock+0x40a/0xd20 kernel/sched/core.c:850, CPU#0: migration/0/19
Modules linked in:
CPU: 0 UID: 0 PID: 19 Comm: migration/0 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Stopper: 0x0 <- 0x0
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1600 [inline]
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1597 [inline]
RIP: 0010:update_rq_clock+0x40a/0xd20 kernel/sched/core.c:850
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 df fc ff ff 90 0f 0b 90 e9 d6 fc ff ff 90 <0f> 0b 90 e9 92 fc ff ff 4c 8d 83 40 0b 00 00 48 b8 00 00 00 00 00
RSP: 0018:ffffc90000187c28 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b853b300 RCX: 0000000000000001
RDX: 0000000000000046 RSI: ffffffff8de5b9eb RDI: ffffffff8c1b1420
RBP: ffffc90000187dd0 R08: 0000000000000001 R09: 0000000000000001
R10: ffff888021b81007 R11: 0000004423c45800 R12: ffffffff90da16e4
R13: ffff8880b853c140 R14: ffff8880341b5b80 R15: ffff8880b853b300
FS:  0000000000000000(0000) GS:ffff888124343000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d9972a9950 CR3: 000000003d6b6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 pick_next_task kernel/sched/core.c:6132 [inline]
 __schedule+0x1b7d/0x6120 kernel/sched/core.c:6852
 __schedule_loop kernel/sched/core.c:6993 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7008
 smpboot_thread_fn+0x893/0xaa0 kernel/smpboot.c:156
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>