------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
migration/0/19 is trying to acquire lock:
ffffffff8e6f1420 (console_owner){-...}-{0:0}, at: console_lock_spinning_enable+0x61/0x80 kernel/printk/printk.c:1902

but task is already holding lock:
ffff8880b843b3e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:660 [inline]
ffff8880b843b3e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:644

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:382
       raw_spin_rq_lock_nested+0x2c/0x140 kernel/sched/core.c:652
       raw_spin_rq_lock kernel/sched/sched.h:1624 [inline]
       _task_rq_lock+0xcf/0x510 kernel/sched/core.c:747
       cgroup_move_task+0x81/0x320 kernel/sched/psi.c:1170
       css_set_move_task+0x285/0x600 kernel/cgroup/cgroup.c:887
       cgroup_post_fork+0x202/0x9b0 kernel/cgroup/cgroup.c:6952
       copy_process+0x5b91/0x7e00 kernel/fork.c:2524
       kernel_clone+0x12e/0x9c0 kernel/fork.c:2721
       user_mode_thread+0xcc/0x110 kernel/fork.c:2797
       rest_init+0x21/0x260 init/main.c:727
       start_kernel+0x484/0x490 init/main.c:1220
       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:166
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:571 [inline]
       try_to_wake_up+0xb5/0x1900 kernel/sched/core.c:4190
       __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+0x52/0x70 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+0xb4/0x530 drivers/tty/serial/8250/8250_port.c:1841
       serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1837 [inline]
       serial8250_default_handle_irq+0xc2/0x290 drivers/tty/serial/8250/8250_port.c:1855
       serial8250_interrupt+0xf8/0x1c0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x235/0x8c0 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+0x35e/0x960 kernel/irq/chip.c:856
       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:198
       __debug_check_no_obj_freed lib/debugobjects.c:1125 [inline]
       debug_check_no_obj_freed+0x31f/0x630 lib/debugobjects.c:1146
       __free_pages_prepare mm/page_alloc.c:1409 [inline]
       __free_frozen_pages+0x3f5/0x1040 mm/page_alloc.c:2943
       qlink_free mm/kasan/quarantine.c:163 [inline]
       qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
       kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
       __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
       kasan_slab_alloc include/linux/kasan.h:253 [inline]
       slab_post_alloc_hook mm/slub.c:4569 [inline]
       slab_alloc_node mm/slub.c:4898 [inline]
       kmem_cache_alloc_node_noprof+0x25a/0x6f0 mm/slub.c:4950
       __alloc_skb+0x140/0x710 net/core/skbuff.c:702
       alloc_skb include/linux/skbuff.h:1383 [inline]
       alloc_skb_with_frags+0xdd/0x760 net/core/skbuff.c:6734
       sock_alloc_send_pskb+0x801/0x980 net/core/sock.c:2998
       unix_dgram_sendmsg+0x3c7/0x1810 net/unix/af_unix.c:2141
       unix_seqpacket_sendmsg+0x12a/0x1d0 net/unix/af_unix.c:2542
       sock_sendmsg_nosec net/socket.c:787 [inline]
       __sock_sendmsg net/socket.c:802 [inline]
       sock_write_iter+0x524/0x5a0 net/socket.c:1254
       do_iter_readv_writev+0x6ee/0x920 fs/read_write.c:829
       vfs_writev+0x360/0xe10 fs/read_write.c:1059
       do_writev+0x28a/0x340 fs/read_write.c:1105
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x10b/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:166
       __wake_up_common_lock kernel/sched/wait.c:124 [inline]
       __wake_up+0x1c/0x60 kernel/sched/wait.c:146
       tty_port_default_wakeup+0x52/0x70 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+0xb4/0x530 drivers/tty/serial/8250/8250_port.c:1841
       serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1837 [inline]
       serial8250_default_handle_irq+0xc2/0x290 drivers/tty/serial/8250/8250_port.c:1855
       serial8250_interrupt+0xf8/0x1c0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x235/0x8c0 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+0x35e/0x960 kernel/irq/chip.c:856
       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:62 [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:762
       start_kernel+0x484/0x490 init/main.c:1220
       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:166
       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+0x3f7/0x5e0 kernel/printk/printk.c:4407
       start_kernel+0x30a/0x490 init/main.c:1157
       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+0x1b1/0x370 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:240
       report_bug+0xb2/0x220 lib/bug.c:278
       handle_bug+0x16a/0x2a0 arch/x86/kernel/traps.c:436
       exc_invalid_op+0x17/0x50 arch/x86/kernel/traps.c:490
       asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
       lockdep_assert_rq_held kernel/sched/sched.h:1612 [inline]
       lockdep_assert_rq_held kernel/sched/sched.h:1609 [inline]
       update_rq_clock+0x40a/0xd20 kernel/sched/core.c:850
       pick_next_task kernel/sched/core.c:6221 [inline]
       __schedule+0x1cd8/0x6820 kernel/sched/core.c:7104
       __schedule_loop kernel/sched/core.c:7267 [inline]
       schedule+0xdd/0x390 kernel/sched/core.c:7282
       smpboot_thread_fn+0x893/0xaa0 kernel/smpboot.c:156
       kthread+0x370/0x450 kernel/kthread.c:436
       ret_from_fork+0x72b/0xd50 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: ffff8880b843b3e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:660 [inline]
 #0: ffff8880b843b3e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:644
 #1: ffffffff8e7d1860 (console_lock){+.+.}-{0:0}, at: _printk+0xcf/0x110 kernel/printk/printk.c:2504
 #2: ffffffff8e7d18d8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline]
 #2: ffffffff8e7d18d8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline]
 #2: ffffffff8e7d18d8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline]
 #2: ffffffff8e7d18d8 (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 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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+0x1b1/0x370 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:240
 report_bug+0xb2/0x220 lib/bug.c:278
 handle_bug+0x16a/0x2a0 arch/x86/kernel/traps.c:436
 exc_invalid_op+0x17/0x50 arch/x86/kernel/traps.c:490
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1612 [inline]
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1609 [inline]
RIP: 0010:update_rq_clock+0x40a/0xd20 kernel/sched/core.c:850
Code: ab 88 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 80 0b 00 00 48 b8 00 00 00 00 00
RSP: 0018:ffffc90000187c20 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b853b380 RCX: 0000000000000001
RDX: 0000000000000046 RSI: ffffffff8def5ccc RDI: ffffffff8c1c2480
RBP: ffffc90000187dd0 R08: 0000000000000001 R09: 0000000000000001
R10: ffff88802a9a9007 R11: 0000000000000000 R12: ffffffff90d7fac4
R13: ffff8880b853c220 R14: ffff8880217d0000 R15: ffff8880b853b380
 pick_next_task kernel/sched/core.c:6221 [inline]
 __schedule+0x1cd8/0x6820 kernel/sched/core.c:7104
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7282
 smpboot_thread_fn+0x893/0xaa0 kernel/smpboot.c:156
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 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:1612 at lockdep_assert_rq_held kernel/sched/sched.h:1612 [inline], CPU#0: migration/0/19
WARNING: kernel/sched/sched.h:1612 at lockdep_assert_rq_held kernel/sched/sched.h:1609 [inline], CPU#0: migration/0/19
WARNING: kernel/sched/sched.h:1612 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 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Stopper: 0x0 <- 0x0
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1612 [inline]
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1609 [inline]
RIP: 0010:update_rq_clock+0x40a/0xd20 kernel/sched/core.c:850
Code: ab 88 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 80 0b 00 00 48 b8 00 00 00 00 00
RSP: 0018:ffffc90000187c20 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b853b380 RCX: 0000000000000001
RDX: 0000000000000046 RSI: ffffffff8def5ccc RDI: ffffffff8c1c2480
RBP: ffffc90000187dd0 R08: 0000000000000001 R09: 0000000000000001
R10: ffff88802a9a9007 R11: 0000000000000000 R12: ffffffff90d7fac4
R13: ffff8880b853c220 R14: ffff8880217d0000 R15: ffff8880b853b380
FS:  0000000000000000(0000) GS:ffff88812437d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000076602000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 pick_next_task kernel/sched/core.c:6221 [inline]
 __schedule+0x1cd8/0x6820 kernel/sched/core.c:7104
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7282
 smpboot_thread_fn+0x893/0xaa0 kernel/smpboot.c:156
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>