------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/6059 is trying to acquire lock:
ffffffff8e2d1680 (console_owner){....}-{0:0}, at: console_lock_spinning_enable+0x61/0x80 kernel/printk/printk.c:1897

but task is already holding lock:
ffff88806a63a398 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:646 [inline]
ffff88806a63a398 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:631

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+0x29/0x130 kernel/sched/core.c:638
       raw_spin_rq_lock kernel/sched/sched.h:1547 [inline]
       task_rq_lock+0xcf/0x490 kernel/sched/core.c:738
       cgroup_move_task+0x81/0x2a0 kernel/sched/psi.c:1170
       css_set_move_task+0x288/0x5f0 kernel/cgroup/cgroup.c:951
       cgroup_post_fork+0x201/0x9d0 kernel/cgroup/cgroup.c:6913
       copy_process+0x602d/0x76a0 kernel/fork.c:2425
       kernel_clone+0xfc/0x930 kernel/fork.c:2609
       user_mode_thread+0xc8/0x110 kernel/fork.c:2685
       rest_init+0x23/0x2b0 init/main.c:722
       start_kernel+0x3f6/0x4e0 init/main.c:1111
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x130/0x190 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:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:557 [inline]
       try_to_wake_up+0xb7/0x1870 kernel/sched/core.c:4181
       __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+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1719
       serial8250_handle_irq+0x761/0xcb0 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:82
       __handle_irq_event_percpu+0x236/0x920 kernel/irq/handle.c:203
       handle_irq_event_percpu kernel/irq/handle.c:240 [inline]
       handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:257
       handle_edge_irq+0x3ca/0x9e0 kernel/irq/chip.c:855
       generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
       handle_irq arch/x86/kernel/irq.c:254 [inline]
       call_irq_handler arch/x86/kernel/irq.c:310 [inline]
       __common_interrupt+0xd0/0x2f0 arch/x86/kernel/irq.c:325
       common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:318
       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:81
       arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
       default_idle+0x13/0x20 arch/x86/kernel/process.c:767
       default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
       cpuidle_idle_call kernel/sched/idle.c:190 [inline]
       do_idle+0x38d/0x500 kernel/sched/idle.c:330
       cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428
       rest_init+0x16b/0x2b0 init/main.c:757
       start_kernel+0x3f6/0x4e0 init/main.c:1111
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x148

-> #2 (&tty->write_wait){-...}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [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+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1719
       __start_tx+0x3df/0x490 drivers/tty/serial/8250/8250_port.c:1426
       serial8250_start_tx+0x368/0x530 drivers/tty/serial/8250/8250_port.c:1535
       __uart_start+0x295/0x500 drivers/tty/serial/serial_core.c:161
       uart_write+0x218/0xb30 drivers/tty/serial/serial_core.c:633
       process_output_block drivers/tty/n_tty.c:561 [inline]
       n_tty_write+0x41e/0x11e0 drivers/tty/n_tty.c:2377
       iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
       file_tty_write.constprop.0+0x503/0x9b0 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+0xd4/0x150 drivers/tty/tty_io.c:1105
       new_sync_write fs/read_write.c:593 [inline]
       vfs_write+0x7d3/0x11d0 fs/read_write.c:686
       ksys_write+0x12a/0x250 fs/read_write.c:738
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xfa0 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:110 [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+0x181/0x1890 drivers/tty/serial/8250/8250_port.c:3301
       console_emit_next_record kernel/printk/printk.c:3111 [inline]
       console_flush_all+0x801/0xc60 kernel/printk/printk.c:3199
       __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
       console_unlock+0xd8/0x210 kernel/printk/printk.c:3298
       vprintk_emit+0x3d7/0x680 kernel/printk/printk.c:2423
       _printk+0xc7/0x100 kernel/printk/printk.c:2448
       register_console+0xc2d/0x11b0 kernel/printk/printk.c:4099
       univ8250_console_init+0x5f/0x90 drivers/tty/serial/8250/8250_core.c:511
       console_init+0x152/0x680 kernel/printk/printk.c:4298
       start_kernel+0x29f/0x4e0 init/main.c:1048
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x130/0x190 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+0x126f/0x1c90 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
       console_lock_spinning_enable+0x72/0x80 kernel/printk/printk.c:1897
       console_emit_next_record kernel/printk/printk.c:3105 [inline]
       console_flush_all+0x7aa/0xc60 kernel/printk/printk.c:3199
       __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
       console_unlock+0xd8/0x210 kernel/printk/printk.c:3298
       vprintk_emit+0x3d7/0x680 kernel/printk/printk.c:2423
       _printk+0xc7/0x100 kernel/printk/printk.c:2448
       __report_bug lib/bug.c:191 [inline]
       report_bug+0x4a9/0x580 lib/bug.c:215
       handle_bug+0x184/0x210 arch/x86/kernel/traps.c:338
       exc_invalid_op+0x17/0x50 arch/x86/kernel/traps.c:392
       asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
       update_entity_lag+0xfb/0x150 kernel/sched/fair.c:697
       dequeue_entity kernel/sched/fair.c:5416 [inline]
       dequeue_entities+0x21c/0x2bb0 kernel/sched/fair.c:7076
       dequeue_task_fair+0x1bc/0x9b0 kernel/sched/fair.c:7175
       block_task kernel/sched/core.c:2157 [inline]
       try_to_block_task kernel/sched/core.c:6553 [inline]
       __schedule+0x54a/0x5de0 kernel/sched/core.c:6864
       __schedule_loop kernel/sched/core.c:7011 [inline]
       schedule+0xe7/0x3a0 kernel/sched/core.c:7026
       do_nanosleep+0x219/0x580 kernel/time/hrtimer.c:2116
       hrtimer_nanosleep+0x155/0x380 kernel/time/hrtimer.c:2163
       common_nsleep+0xa1/0xd0 kernel/time/posix-timers.c:1352
       __do_sys_clock_nanosleep kernel/time/posix-timers.c:1398 [inline]
       __se_sys_clock_nanosleep kernel/time/posix-timers.c:1375 [inline]
       __x64_sys_clock_nanosleep+0x34d/0x4a0 kernel/time/posix-timers.c:1375
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xfa0 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-executor.0/6059:
 #0: ffff88806a63a398 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:646 [inline]
 #0: ffff88806a63a398 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:631
 #1: ffffffff8e3b1ac0 (console_lock){+.+.}-{0:0}, at: _printk+0xc7/0x100 kernel/printk/printk.c:2448
 #2: ffffffff8e3b1b30 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
 #2: ffffffff8e3b1b30 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:335 [inline]
 #2: ffffffff8e3b1b30 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:289 [inline]
 #2: ffffffff8e3b1b30 (console_srcu){....}-{0:0}, at: console_flush_all+0x158/0xc60 kernel/printk/printk.c:3176

stack backtrace:
CPU: 2 UID: 0 PID: 6059 Comm: syz-executor.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2043
 check_noncircular+0x14c/0x170 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+0x126f/0x1c90 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
 console_lock_spinning_enable+0x72/0x80 kernel/printk/printk.c:1897
 console_emit_next_record kernel/printk/printk.c:3105 [inline]
 console_flush_all+0x7aa/0xc60 kernel/printk/printk.c:3199
 __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
 console_unlock+0xd8/0x210 kernel/printk/printk.c:3298
 vprintk_emit+0x3d7/0x680 kernel/printk/printk.c:2423
 _printk+0xc7/0x100 kernel/printk/printk.c:2448
 __report_bug lib/bug.c:191 [inline]
 report_bug+0x4a9/0x580 lib/bug.c:215
 handle_bug+0x184/0x210 arch/x86/kernel/traps.c:338
 exc_invalid_op+0x17/0x50 arch/x86/kernel/traps.c:392
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
RIP: 0010:update_entity_lag+0xfb/0x150 kernel/sched/fair.c:697
Code: d8 48 89 f9 4c 39 e0 49 0f 4c c4 49 39 ec 48 0f 4c e8 48 c1 e9 03 80 3c 11 00 75 30 48 89 6b 78 5b 5d 41 5c c3 cc cc cc cc 90 <0f> 0b 90 e9 34 ff ff ff 48 89 ef 48 89 de e8 e2 e7 fd ff 48 89 c5
RSP: 0018:ffffc90004567950 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff88802b75c980 RCX: 0000000000006c00
RDX: 1ffff110056eb93a RSI: ffff88802b75c980 RDI: ffff88802b75c9d0
RBP: ffff88803350f000 R08: 0000000000000000 R09: fffffbfff2103eda
R10: ffffffff9081f6d7 R11: 0000000000000001 R12: ffff88802b75ca20
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff88802b75c980
 dequeue_entity kernel/sched/fair.c:5416 [inline]
 dequeue_entities+0x21c/0x2bb0 kernel/sched/fair.c:7076
 dequeue_task_fair+0x1bc/0x9b0 kernel/sched/fair.c:7175
 block_task kernel/sched/core.c:2157 [inline]
 try_to_block_task kernel/sched/core.c:6553 [inline]
 __schedule+0x54a/0x5de0 kernel/sched/core.c:6864
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7026
 do_nanosleep+0x219/0x580 kernel/time/hrtimer.c:2116
 hrtimer_nanosleep+0x155/0x380 kernel/time/hrtimer.c:2163
 common_nsleep+0xa1/0xd0 kernel/time/posix-timers.c:1352
 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1398 [inline]
 __se_sys_clock_nanosleep kernel/time/posix-timers.c:1375 [inline]
 __x64_sys_clock_nanosleep+0x34d/0x4a0 kernel/time/posix-timers.c:1375
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f21b5aa7ef5
Code: 24 0c 89 3c 24 48 89 4c 24 18 e8 f6 b9 ff ff 4c 8b 54 24 18 48 8b 54 24 10 41 89 c0 8b 74 24 0c 8b 3c 24 b8 e6 00 00 00 0f 05 <44> 89 c7 48 89 04 24 e8 4f ba ff ff 48 8b 04 24 48 83 c4 28 f7 d8
RSP: 002b:00007ffe889ad8b0 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 00000000000002c4 RCX: 00007f21b5aa7ef5
RDX: 00007ffe889ad8f0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffe889ad97c R08: 0000000000000000 R09: 00007f21b66d6000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000032
R13: 0000000000023923 R14: 0000000000023840 R15: 0000000000000006
 </TASK>
WARNING: CPU: 2 PID: 6059 at kernel/sched/fair.c:697 update_entity_lag+0xfb/0x150 kernel/sched/fair.c:697
Modules linked in:
CPU: 2 UID: 0 PID: 6059 Comm: syz-executor.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:update_entity_lag+0xfb/0x150 kernel/sched/fair.c:697
Code: d8 48 89 f9 4c 39 e0 49 0f 4c c4 49 39 ec 48 0f 4c e8 48 c1 e9 03 80 3c 11 00 75 30 48 89 6b 78 5b 5d 41 5c c3 cc cc cc cc 90 <0f> 0b 90 e9 34 ff ff ff 48 89 ef 48 89 de e8 e2 e7 fd ff 48 89 c5
RSP: 0018:ffffc90004567950 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff88802b75c980 RCX: 0000000000006c00
RDX: 1ffff110056eb93a RSI: ffff88802b75c980 RDI: ffff88802b75c9d0
RBP: ffff88803350f000 R08: 0000000000000000 R09: fffffbfff2103eda
R10: ffffffff9081f6d7 R11: 0000000000000001 R12: ffff88802b75ca20
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff88802b75c980
FS:  00005555671e1480(0000) GS:ffff8880d6c0a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020204000 CR3: 0000000033717000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 dequeue_entity kernel/sched/fair.c:5416 [inline]
 dequeue_entities+0x21c/0x2bb0 kernel/sched/fair.c:7076
 dequeue_task_fair+0x1bc/0x9b0 kernel/sched/fair.c:7175
 block_task kernel/sched/core.c:2157 [inline]
 try_to_block_task kernel/sched/core.c:6553 [inline]
 __schedule+0x54a/0x5de0 kernel/sched/core.c:6864
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7026
 do_nanosleep+0x219/0x580 kernel/time/hrtimer.c:2116
 hrtimer_nanosleep+0x155/0x380 kernel/time/hrtimer.c:2163
 common_nsleep+0xa1/0xd0 kernel/time/posix-timers.c:1352
 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1398 [inline]
 __se_sys_clock_nanosleep kernel/time/posix-timers.c:1375 [inline]
 __x64_sys_clock_nanosleep+0x34d/0x4a0 kernel/time/posix-timers.c:1375
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f21b5aa7ef5
Code: 24 0c 89 3c 24 48 89 4c 24 18 e8 f6 b9 ff ff 4c 8b 54 24 18 48 8b 54 24 10 41 89 c0 8b 74 24 0c 8b 3c 24 b8 e6 00 00 00 0f 05 <44> 89 c7 48 89 04 24 e8 4f ba ff ff 48 8b 04 24 48 83 c4 28 f7 d8
RSP: 002b:00007ffe889ad8b0 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 00000000000002c4 RCX: 00007f21b5aa7ef5
RDX: 00007ffe889ad8f0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffe889ad97c R08: 0000000000000000 R09: 00007f21b66d6000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000032
R13: 0000000000023923 R14: 0000000000023840 R15: 0000000000000006
 </TASK>