kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 15950 Comm: syz-executor3 Not tainted 4.19.0-rc4-next-20180921+ #77
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__fire_sched_out_preempt_notifiers kernel/sched/core.c:2502 [inline]
RIP: 0010:fire_sched_out_preempt_notifiers kernel/sched/core.c:2510 [inline]
RIP: 0010:prepare_task_switch kernel/sched/core.c:2616 [inline]
RIP: 0010:context_switch kernel/sched/core.c:2795 [inline]
RIP: 0010:__schedule+0x1144/0x1ed0 kernel/sched/core.c:3479
Code: 89 e0 48 c1 e8 03 42 80 3c 28 00 0f 85 7e 08 00 00 4d 8b 24 24 4d 85 e4 0f 84 7e f5 ff ff 49 8d 7c 24 10 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 a4 e8 e0 bb 00 fa eb 9d 48 8d bb 28 04 00 00 48
RSP: 0018:ffff8801906a7290 EFLAGS: 00010806
RAX: 1bd5a00000000022 RBX: ffff8801ccc24180 RCX: 1ffff100319ba8ff
RDX: 0000000040000002 RSI: 0000000000000000 RDI: dead000000000110
RBP: ffff8801906a7468 R08: ffff8801bfb10540 R09: fffff520004f0a47
R10: fffff520004f0a47 R11: ffffc9000278523b R12: dead000000000100
R13: dffffc0000000000 R14: ffff8801dac2cc40 R15: ffff8801bfb10540
FS:  00007f2e64334700(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2e225000 CR3: 00000001ccd86000 CR4: 00000000001426f0
Call Trace:
 preempt_schedule_common+0x1f/0xd0 kernel/sched/core.c:3603
 preempt_schedule+0x4d/0x60 kernel/sched/core.c:3629
 ___preempt_schedule+0x16/0x18
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
 _raw_spin_unlock_irqrestore+0xbb/0xd0 kernel/locking/spinlock.c:184
 try_to_wake_up+0x10a/0x12f0 kernel/sched/core.c:2060
 wake_up_process kernel/sched/core.c:2128 [inline]
 wake_up_q+0xa4/0x100 kernel/sched/core.c:441
 futex_wake+0x61f/0x760 kernel/futex.c:1556
 do_futex+0x2e4/0x26d0 kernel/futex.c:3533
 __do_sys_futex kernel/futex.c:3589 [inline]
 __se_sys_futex kernel/futex.c:3557 [inline]
 __x64_sys_futex+0x472/0x6a0 kernel/futex.c:3557
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457679
Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f2e64333cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 000000000072bf08 RCX: 0000000000457679
RDX: 0000000000000000 RSI: 0000000000000081 RDI: 000000000072bf0c
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000072bf0c
R13: 00007ffca8eea89f R14: 00007f2e643349c0 R15: 0000000000000000
Modules linked in:

======================================================
WARNING: possible circular locking dependency detected
4.19.0-rc4-next-20180921+ #77 Not tainted
------------------------------------------------------
syz-executor3/15950 is trying to acquire lock:
0000000051dd5d93 ((console_sem).lock){-.-.}, at: down_trylock+0x13/0x70 kernel/locking/semaphore.c:136

but task is already holding lock:
00000000f07381c9 (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1125 [inline]
00000000f07381c9 (&rq->lock){-.-.}, at: __schedule+0x236/0x1ed0 kernel/sched/core.c:3417

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&rq->lock){-.-.}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
       _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
       rq_lock kernel/sched/sched.h:1125 [inline]
       task_fork_fair+0xb0/0x6d0 kernel/sched/fair.c:9674
       sched_fork+0x443/0xba0 kernel/sched/core.c:2358
       copy_process+0x2585/0x8780 kernel/fork.c:1887
       _do_fork+0x1cb/0x11c0 kernel/fork.c:2216
       kernel_thread+0x34/0x40 kernel/fork.c:2275
       rest_init+0x22/0xe5 init/main.c:408
       start_kernel+0x8bc/0x8f7 init/main.c:739
       x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
       x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
       secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

-> #1 (&p->pi_lock){-.-.}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
       try_to_wake_up+0xd2/0x12f0 kernel/sched/core.c:1964
       wake_up_process+0x10/0x20 kernel/sched/core.c:2128
       __up.isra.1+0x1c0/0x2a0 kernel/locking/semaphore.c:262
       up+0x13c/0x1c0 kernel/locking/semaphore.c:187
       __up_console_sem+0xbe/0x1b0 kernel/printk/printk.c:243
       console_unlock+0x80c/0x1150 kernel/printk/printk.c:2426
       vprintk_emit+0x33d/0x930 kernel/printk/printk.c:1921
       vprintk_default+0x28/0x30 kernel/printk/printk.c:1962
       vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
       printk+0xa7/0xcf kernel/printk/printk.c:1995
       load_umh+0x51/0xbd net/bpfilter/bpfilter_kern.c:98
       do_one_initcall+0x140/0x956 init/main.c:885
       do_initcall_level init/main.c:953 [inline]
       do_initcalls init/main.c:961 [inline]
       do_basic_setup init/main.c:979 [inline]
       kernel_init_freeable+0x4bb/0x5ae init/main.c:1144
       kernel_init+0x11/0x1b2 init/main.c:1063
       ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

-> #0 ((console_sem).lock){-.-.}:
       lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
       down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
       __down_trylock_console_sem+0xae/0x200 kernel/printk/printk.c:226
       console_trylock+0x15/0xa0 kernel/printk/printk.c:2244
       console_trylock_spinning kernel/printk/printk.c:1648 [inline]
       vprintk_emit+0x322/0x930 kernel/printk/printk.c:1920
       vprintk_default+0x28/0x30 kernel/printk/printk.c:1962
       vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
       printk+0xa7/0xcf kernel/printk/printk.c:1995
       kasan_die_handler.cold.22+0x11/0x30 arch/x86/mm/kasan_init_64.c:250
       notifier_call_chain+0x17e/0x380 kernel/notifier.c:93
       __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
       atomic_notifier_call_chain+0x96/0x190 kernel/notifier.c:193
       notify_die+0x1bd/0x2d0 kernel/notifier.c:549
       do_general_protection+0x25b/0x340 arch/x86/kernel/traps.c:573
       general_protection+0x1e/0x30 arch/x86/entry/entry_64.S:1138
       __fire_sched_out_preempt_notifiers kernel/sched/core.c:2502 [inline]
       fire_sched_out_preempt_notifiers kernel/sched/core.c:2510 [inline]
       prepare_task_switch kernel/sched/core.c:2616 [inline]
       context_switch kernel/sched/core.c:2795 [inline]
       __schedule+0x1144/0x1ed0 kernel/sched/core.c:3479
       preempt_schedule_common+0x1f/0xd0 kernel/sched/core.c:3603
       preempt_schedule+0x4d/0x60 kernel/sched/core.c:3629
       ___preempt_schedule+0x16/0x18
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
       _raw_spin_unlock_irqrestore+0xbb/0xd0 kernel/locking/spinlock.c:184
       try_to_wake_up+0x10a/0x12f0 kernel/sched/core.c:2060
       wake_up_process kernel/sched/core.c:2128 [inline]
       wake_up_q+0xa4/0x100 kernel/sched/core.c:441
       futex_wake+0x61f/0x760 kernel/futex.c:1556
       do_futex+0x2e4/0x26d0 kernel/futex.c:3533
       __do_sys_futex kernel/futex.c:3589 [inline]
       __se_sys_futex kernel/futex.c:3557 [inline]
       __x64_sys_futex+0x472/0x6a0 kernel/futex.c:3557
       do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
  (console_sem).lock --> &p->pi_lock --> &rq->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&rq->lock);
                               lock(&p->pi_lock);
                               lock(&rq->lock);
  lock((console_sem).lock);

 *** DEADLOCK ***

2 locks held by syz-executor3/15950:
 #0: 00000000f07381c9 (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1125 [inline]
 #0: 00000000f07381c9 (&rq->lock){-.-.}, at: __schedule+0x236/0x1ed0 kernel/sched/core.c:3417
 #1: 00000000dc1a542b (rcu_read_lock){....}, at: atomic_notifier_call_chain+0x0/0x190 kernel/notifier.c:329

stack backtrace:
CPU: 0 PID: 15950 Comm: syz-executor3 Not tainted 4.19.0-rc4-next-20180921+ #77
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d3/0x2c4 lib/dump_stack.c:113
 print_circular_bug.isra.33.cold.54+0x1bd/0x27d kernel/locking/lockdep.c:1221
 check_prev_add kernel/locking/lockdep.c:1861 [inline]
 check_prevs_add kernel/locking/lockdep.c:1974 [inline]
 validate_chain kernel/locking/lockdep.c:2415 [inline]
 __lock_acquire+0x33e4/0x4ec0 kernel/locking/lockdep.c:3411
 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
 down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
 __down_trylock_console_sem+0xae/0x200 kernel/printk/printk.c:226
 console_trylock+0x15/0xa0 kernel/printk/printk.c:2244
 console_trylock_spinning kernel/printk/printk.c:1648 [inline]
 vprintk_emit+0x322/0x930 kernel/printk/printk.c:1920
 vprintk_default+0x28/0x30 kernel/printk/printk.c:1962
 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
 printk+0xa7/0xcf kernel/printk/printk.c:1995
 kasan_die_handler.cold.22+0x11/0x30 arch/x86/mm/kasan_init_64.c:250
 notifier_call_chain+0x17e/0x380 kernel/notifier.c:93
 __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
 atomic_notifier_call_chain+0x96/0x190 kernel/notifier.c:193
 notify_die+0x1bd/0x2d0 kernel/notifier.c:549
 do_general_protection+0x25b/0x340 arch/x86/kernel/traps.c:573
 general_protection+0x1e/0x30 arch/x86/entry/entry_64.S:1138
RIP: 0010:__fire_sched_out_preempt_notifiers kernel/sched/core.c:2502 [inline]
RIP: 0010:fire_sched_out_preempt_notifiers kernel/sched/core.c:2510 [inline]
RIP: 0010:prepare_task_switch kernel/sched/core.c:2616 [inline]
RIP: 0010:context_switch kernel/sched/core.c:2795 [inline]
RIP: 0010:__schedule+0x1144/0x1ed0 kernel/sched/core.c:3479
Code: 89 e0 48 c1 e8 03 42 80 3c 28 00 0f 85 7e 08 00 00 4d 8b 24 24 4d 85 e4 0f 84 7e f5 ff ff 49 8d 7c 24 10 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 a4 e8 e0 bb 00 fa eb 9d 48 8d bb 28 04 00 00 48
RSP: 0018:ffff8801906a7290 EFLAGS: 00010806
RAX: 1bd5a00000000022 RBX: ffff8801ccc24180 RCX: 1ffff100319ba8ff
RDX: 0000000040000002 RSI: 0000000000000000 RDI: dead000000000110
RBP: ffff8801906a7468 R08: ffff8801bfb10540 R09: fffff520004f0a47
R10: fffff520004f0a47 R11: ffffc9000278523b R12: dead000000000100
R13: dffffc0000000000 R14: ffff8801dac2cc40 R15: ffff8801bfb10540
 preempt_schedule_common+0x1f/0xd0 kernel/sched/core.c:3603
 preempt_schedule+0x4d/0x60 kernel/sched/core.c:3629
 ___preempt_schedule+0x16/0x18
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
 _raw_spin_unlock_irqrestore+0xbb/0xd0 kernel/locking/spinlock.c:184
 try_to_wake_up+0x10a/0x12f0 kernel/sched/core.c:2060
 wake_up_process kernel/sched/core.c:2128 [inline]
 wake_up_q+0xa4/0x100 kernel/sched/core.c:441
 futex_wake+0x61f/0x760 kernel/futex.c:1556
 do_futex+0x2e4/0x26d0 kernel/futex.c:3533
 __do_sys_futex kernel/futex.c:3589 [inline]
 __se_sys_futex kernel/futex.c:3557 [inline]
 __x64_sys_futex+0x472/0x6a0 kernel/futex.c:3557
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
Lost 16 message(s)!
---[ end trace c9373ce16d1ae714 ]---
RIP: 0010:__fire_sched_out_preempt_notifiers kernel/sched/core.c:2502 [inline]
RIP: 0010:fire_sched_out_preempt_notifiers kernel/sched/core.c:2510 [inline]
RIP: 0010:prepare_task_switch kernel/sched/core.c:2616 [inline]
RIP: 0010:context_switch kernel/sched/core.c:2795 [inline]
RIP: 0010:__schedule+0x1144/0x1ed0 kernel/sched/core.c:3479
Code: 89 e0 48 c1 e8 03 42 80 3c 28 00 0f 85 7e 08 00 00 4d 8b 24 24 4d 85 e4 0f 84 7e f5 ff ff 49 8d 7c 24 10 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 a4 e8 e0 bb 00 fa eb 9d 48 8d bb 28 04 00 00 48
RSP: 0018:ffff8801906a7290 EFLAGS: 00010806
RAX: 1bd5a00000000022 RBX: ffff8801ccc24180 RCX: 1ffff100319ba8ff
RDX: 0000000040000002 RSI: 0000000000000000 RDI: dead000000000110
RBP: ffff8801906a7468 R08: ffff8801bfb10540 R09: fffff520004f0a47
R10: fffff520004f0a47 R11: ffffc9000278523b R12: dead000000000100
R13: dffffc0000000000 R14: ffff8801dac2cc40 R15: ffff8801bfb10540
FS:  00007f2e64334700(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2e225000 CR3: 00000001ccd86000 CR4: 00000000001426f0