------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
migration/0/19 is trying to acquire lock:
ffffffff8eaf3f60 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:2026 [inline]
ffffffff8eaf3f60 (console_owner){....}-{0:0}, at: vprintk_emit+0x4c0/0x6b0 kernel/printk/printk.c:2478

but task is already holding lock:
ffff88802b23b660 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:675 [inline]
ffff88802b23b660 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:659

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&rq->__lock){-.-.}-{2:2}:
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:382
       raw_spin_rq_lock_nested+0x2c/0x140 kernel/sched/core.c:667
       raw_spin_rq_lock kernel/sched/sched.h:1653 [inline]
       _task_rq_lock+0xcf/0x500 kernel/sched/core.c:762
       cgroup_move_task+0x81/0x320 kernel/sched/psi.c:1170
       css_set_move_task+0x285/0x600 kernel/cgroup/cgroup.c:925
       cgroup_post_fork+0x1f9/0x9a0 kernel/cgroup/cgroup.c:6988
       copy_process+0x6b7a/0x8030 kernel/fork.c:2550
       kernel_clone+0x176/0x9d0 kernel/fork.c:2748
       user_mode_thread+0xcc/0x110 kernel/fork.c:2824
       rest_init+0x21/0x260 init/main.c:682
       start_kernel+0x48e/0x490 init/main.c:1175
       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/0x158

-> #3 (&p->pi_lock){-.-.}-{2:2}:
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       __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+0xbd/0x1c90 kernel/sched/core.c:4292
       __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:1723
       serial8250_handle_irq_locked+0x770/0x9a0 drivers/tty/serial/8250/8250_port.c:1837
       serial8250_handle_irq.part.0+0xb4/0x530 drivers/tty/serial/8250/8250_port.c:1853
       serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1849 [inline]
       serial8250_default_handle_irq+0xc2/0x280 drivers/tty/serial/8250/8250_port.c:1867
       serial8250_interrupt+0xf8/0x1b0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x232/0x880 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+0x34c/0x950 kernel/irq/chip.c:859
       generic_handle_irq_desc include/linux/irqdesc.h:188 [inline]
       handle_irq arch/x86/kernel/irq.c:209 [inline]
       call_irq_handler arch/x86/kernel/irq.c:265 [inline]
       __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:280
       common_interrupt+0xb9/0xe0 arch/x86/kernel/irq.c:273
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:665
       native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
       pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
       arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline]
       default_idle+0x9/0x10 arch/x86/kernel/process.c:768
       default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
       cpuidle_idle_call kernel/sched/idle.c:199 [inline]
       do_idle+0x3a7/0x5b0 kernel/sched/idle.c:355
       cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:454
       start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312
       common_startup_64+0x13e/0x158

-> #2 (&tty->write_wait){-...}-{3:3}:
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       __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+0x47/0x60 drivers/tty/tty_port.c:67
       serial8250_tx_chars+0x68f/0x860 drivers/tty/serial/8250/8250_port.c:1723
       __start_tx+0x3e4/0x490 drivers/tty/serial/8250/8250_port.c:1430
       serial8250_start_tx+0x368/0x540 drivers/tty/serial/8250/8250_port.c:1539
       __uart_start+0x295/0x510 drivers/tty/serial/serial_core.c:161
       uart_write+0x211/0xb20 drivers/tty/serial/serial_core.c:629
       process_output_block drivers/tty/n_tty.c:557 [inline]
       n_tty_write+0x431/0x1160 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/0x1050 fs/read_write.c:687
       ksys_write+0x12a/0x250 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&port_lock_key){-...}-{3:3}:
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       __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:719 [inline]
       serial8250_console_write+0x177/0x1a50 drivers/tty/serial/8250/8250_port.c:3344
       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+0x3d5/0x5b0 kernel/printk/printk.c:4407
       start_kernel+0x314/0x490 init/main.c:1112
       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/0x158

-> #0 (console_owner){....}-{0:0}:
       check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       console_trylock_spinning kernel/printk/printk.c:2026 [inline]
       vprintk_emit+0x4d1/0x6b0 kernel/printk/printk.c:2478
       _printk+0xcf/0x110 kernel/printk/printk.c:2504
       __report_bug.cold+0x34/0x141 lib/bug.c:248
       report_bug+0xb2/0x220 lib/bug.c:286
       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:593
       lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline]
       lockdep_assert_rq_held kernel/sched/sched.h:1638 [inline]
       update_rq_clock+0x40a/0xd20 kernel/sched/core.c:865
       pick_next_task kernel/sched/core.c:6338 [inline]
       __schedule+0x1e2d/0x6730 kernel/sched/core.c:7149
       __schedule_loop kernel/sched/core.c:7311 [inline]
       schedule+0xdd/0x2c0 kernel/sched/core.c:7326
       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 ***

1 lock held by migration/0/19:
 #0: ffff88802b23b660 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:675 [inline]
 #0: ffff88802b23b660 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:659

stack backtrace:
CPU: 0 UID: 0 PID: 19 Comm: migration/0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
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+0xeb/0xe60 kernel/locking/lockdep.c:3165
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
 console_trylock_spinning kernel/printk/printk.c:2026 [inline]
 vprintk_emit+0x4d1/0x6b0 kernel/printk/printk.c:2478
 _printk+0xcf/0x110 kernel/printk/printk.c:2504
 __report_bug.cold+0x34/0x141 lib/bug.c:248
 report_bug+0xb2/0x220 lib/bug.c:286
 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:593
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline]
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1638 [inline]
RIP: 0010:update_rq_clock+0x40a/0xd20 kernel/sched/core.c:865
Code: ab c8 0b 00 00 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e 41 5f e9 d8 6f e6 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 c0 0b 00 00 48 b8 00 00 00 00 00
RSP: 0018:ffffc9000045fc28 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff88802b33b600 RCX: 0000000000000001
RDX: 0000000000000046 RSI: ffffffff8e183111 RDI: ffffffff8c400a80
RBP: ffffc9000045fdd0 R08: 0000000000000001 R09: 0000000000000001
R10: ffff88806b806007 R11: 0000000bf5b29000 R12: ffffffff9122dd84
R13: ffff88802b33c4e0 R14: ffff888024812540 R15: ffff88802b23c198
 pick_next_task kernel/sched/core.c:6338 [inline]
 __schedule+0x1e2d/0x6730 kernel/sched/core.c:7149
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 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:1641 at lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline], CPU#0: migration/0/19
WARNING: kernel/sched/sched.h:1641 at lockdep_assert_rq_held kernel/sched/sched.h:1638 [inline], CPU#0: migration/0/19
WARNING: kernel/sched/sched.h:1641 at update_rq_clock+0x40a/0xd20 kernel/sched/core.c:865, 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: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Stopper: 0x0 <- 0x0
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline]
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1638 [inline]
RIP: 0010:update_rq_clock+0x40a/0xd20 kernel/sched/core.c:865
Code: ab c8 0b 00 00 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e 41 5f e9 d8 6f e6 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 c0 0b 00 00 48 b8 00 00 00 00 00
RSP: 0018:ffffc9000045fc28 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff88802b33b600 RCX: 0000000000000001
RDX: 0000000000000046 RSI: ffffffff8e183111 RDI: ffffffff8c400a80
RBP: ffffc9000045fdd0 R08: 0000000000000001 R09: 0000000000000001
R10: ffff88806b806007 R11: 0000000bf5b29000 R12: ffffffff9122dd84
R13: ffff88802b33c4e0 R14: ffff888024812540 R15: ffff88802b23c198
FS:  0000000000000000(0000) GS:ffff888096be1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f73d60b8 CR3: 0000000029a59000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 pick_next_task kernel/sched/core.c:6338 [inline]
 __schedule+0x1e2d/0x6730 kernel/sched/core.c:7149
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 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>