------------[ cut here ]------------ ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G U L ------------------------------------------------------ syz.6.9254/32305 is trying to acquire lock: ffffffff8e6f35e0 (console_owner){-.-.}-{0:0}, at: console_lock_spinning_enable+0x61/0x80 kernel/printk/printk.c:1902 but task is already holding lock: ffff8880b843b0e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:655 [inline] ffff8880b843b0e0 (&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:6910 copy_process+0x5f26/0x79b0 kernel/fork.c:2467 kernel_clone+0xfc/0x930 kernel/fork.c:2654 user_mode_thread+0xcc/0x110 kernel/fork.c:2730 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 autoremove_wake_function+0x16/0x150 kernel/sched/wait.c:403 __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: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+0x1ad/0x910 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 finish_task_switch.isra.0+0x20e/0xb80 kernel/sched/core.c:5152 context_switch kernel/sched/core.c:5298 [inline] __schedule+0xff6/0x6020 kernel/sched/core.c:6907 __schedule_loop kernel/sched/core.c:6989 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7004 futex_do_wait+0x88/0x180 kernel/futex/waitwake.c:358 __futex_wait+0x1c4/0x300 kernel/futex/waitwake.c:687 futex_wait+0xed/0x380 kernel/futex/waitwake.c:715 do_futex+0x1ef/0x350 kernel/futex/syscalls.c:130 __do_sys_futex kernel/futex/syscalls.c:207 [inline] __se_sys_futex kernel/futex/syscalls.c:188 [inline] __x64_sys_futex+0x34f/0x4d0 kernel/futex/syscalls.c:188 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: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: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 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline] _raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:407 [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+0x29d/0xb20 drivers/tty/serial/serial_core.c:634 process_output_block drivers/tty/n_tty.c:557 [inline] n_tty_write+0x44f/0x12d0 drivers/tty/n_tty.c:2366 iterate_tty_write drivers/tty/tty_io.c:1006 [inline] file_tty_write.isra.0+0x4d2/0x890 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:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 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 -> #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:3301 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:4224 univ8250_console_init+0x6f/0x80 drivers/tty/serial/8250/8250_core.c:515 console_init+0x371/0x520 kernel/printk/printk.c:4423 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+0x17c/0x330 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+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: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:6129 [inline] __schedule+0x1b19/0x6020 kernel/sched/core.c:6848 __schedule_loop kernel/sched/core.c:6989 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7004 do_nanosleep+0x206/0x560 kernel/time/hrtimer.c:2124 hrtimer_nanosleep+0x156/0x360 kernel/time/hrtimer.c:2171 common_nsleep+0xa1/0xd0 kernel/time/posix-timers.c:1345 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1391 [inline] __se_sys_clock_nanosleep kernel/time/posix-timers.c:1368 [inline] __x64_sys_clock_nanosleep+0x336/0x480 kernel/time/posix-timers.c:1368 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 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.6.9254/32305: #0: ffff8880b843b0e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:655 [inline] #0: ffff8880b843b0e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:639 #1: ffffffff8e7d3a20 (console_lock){+.+.}-{0:0}, at: _printk+0xcf/0x110 kernel/printk/printk.c:2504 #2: ffffffff8e7d3a98 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:317 [inline] #2: ffffffff8e7d3a98 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline] #2: ffffffff8e7d3a98 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline] #2: ffffffff8e7d3a98 (console_srcu){....}-{0:0}, at: console_flush_one_record+0xfd/0xe50 kernel/printk/printk.c:3246 stack backtrace: CPU: 0 UID: 0 PID: 32305 Comm: syz.6.9254 Tainted: G U L syzkaller #0 PREEMPT(full) Tainted: [U]=USER, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 Call Trace: __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: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+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: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 e9 d8 7b ac 09 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:ffffc9000b067a78 EFLAGS: 00010046 RAX: 0000000000000000 RBX: ffff8880b853b080 RCX: 0000000000000001 RDX: 0000000000000046 RSI: ffffffff8de4ddbd RDI: ffffffff8c1ad620 RBP: ffffc9000b067c20 R08: 0000000000000001 R09: 0000000000000001 R10: ffff88801f3a0080 R11: 00000000000002a8 R12: ffffffff90d928d4 R13: ffff8880b853bec0 R14: ffff8880277b9e40 R15: ffff8880b853b080 pick_next_task kernel/sched/core.c:6129 [inline] __schedule+0x1b19/0x6020 kernel/sched/core.c:6848 __schedule_loop kernel/sched/core.c:6989 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7004 do_nanosleep+0x206/0x560 kernel/time/hrtimer.c:2124 hrtimer_nanosleep+0x156/0x360 kernel/time/hrtimer.c:2171 common_nsleep+0xa1/0xd0 kernel/time/posix-timers.c:1345 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1391 [inline] __se_sys_clock_nanosleep kernel/time/posix-timers.c:1368 [inline] __x64_sys_clock_nanosleep+0x336/0x480 kernel/time/posix-timers.c:1368 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 RIP: 0033:0x7f471c95c84e Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08 RSP: 002b:00007ffd7b10fec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6 RAX: ffffffffffffffda RBX: 000055558e409500 RCX: 00007f471c95c84e RDX: 00007ffd7b10ff20 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f471cc17da0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000119a43 R13: 00007f471cc1618c R14: 00000000001197ae R15: 00007ffd7b110050 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: syz.6.9254/32305 WARNING: kernel/sched/sched.h:1600 at lockdep_assert_rq_held kernel/sched/sched.h:1597 [inline], CPU#0: syz.6.9254/32305 WARNING: kernel/sched/sched.h:1600 at update_rq_clock+0x40a/0xd20 kernel/sched/core.c:850, CPU#0: syz.6.9254/32305 Modules linked in: CPU: 0 UID: 0 PID: 32305 Comm: syz.6.9254 Tainted: G U L syzkaller #0 PREEMPT(full) Tainted: [U]=USER, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 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 e9 d8 7b ac 09 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:ffffc9000b067a78 EFLAGS: 00010046 RAX: 0000000000000000 RBX: ffff8880b853b080 RCX: 0000000000000001 RDX: 0000000000000046 RSI: ffffffff8de4ddbd RDI: ffffffff8c1ad620 RBP: ffffc9000b067c20 R08: 0000000000000001 R09: 0000000000000001 R10: ffff88801f3a0080 R11: 00000000000002a8 R12: ffffffff90d928d4 R13: ffff8880b853bec0 R14: ffff8880277b9e40 R15: ffff8880b853b080 FS: 000055558e409500(0000) GS:ffff888124392000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000037a000 CR3: 0000000026cce000 CR4: 00000000003526f0 Call Trace: pick_next_task kernel/sched/core.c:6129 [inline] __schedule+0x1b19/0x6020 kernel/sched/core.c:6848 __schedule_loop kernel/sched/core.c:6989 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7004 do_nanosleep+0x206/0x560 kernel/time/hrtimer.c:2124 hrtimer_nanosleep+0x156/0x360 kernel/time/hrtimer.c:2171 common_nsleep+0xa1/0xd0 kernel/time/posix-timers.c:1345 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1391 [inline] __se_sys_clock_nanosleep kernel/time/posix-timers.c:1368 [inline] __x64_sys_clock_nanosleep+0x336/0x480 kernel/time/posix-timers.c:1368 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 RIP: 0033:0x7f471c95c84e Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08 RSP: 002b:00007ffd7b10fec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6 RAX: ffffffffffffffda RBX: 000055558e409500 RCX: 00007f471c95c84e RDX: 00007ffd7b10ff20 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f471cc17da0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000119a43 R13: 00007f471cc1618c R14: 00000000001197ae R15: 00007ffd7b110050