kasan: CONFIG_KASAN_INLINE enabled
kobject: 'loop2' (00000000986e5874): kobject_uevent_env
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 15022 Comm: syz-executor4 Not tainted 4.19.0-rc4-next-20180921+ #77
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
------------[ cut here ]------------
RIP: 0010:__fire_sched_in_preempt_notifiers kernel/sched/core.c:2486 [inline]
RIP: 0010:fire_sched_in_preempt_notifiers kernel/sched/core.c:2492 [inline]
RIP: 0010:finish_task_switch+0x3a4/0x900 kernel/sched/core.c:2684
downgrading a read lock
Code: 3d 04 00 00 4d 8b bc 24 50 03 00 00 4d 85 ff 0f 84 ab fe ff ff 49 bc 00 00 00 00 00 fc ff df 49 8d 7f 10 48 89 f9 48 c1 e9 03 <42> 80 3c 21 00 0f 85 da 03 00 00 49 8b 4f 10 48 89 ce 48 c1 ee 03
WARNING: CPU: 0 PID: 15021 at kernel/locking/lockdep.c:3623 __lock_downgrade kernel/locking/lockdep.c:3623 [inline]
WARNING: CPU: 0 PID: 15021 at kernel/locking/lockdep.c:3623 lock_downgrade+0x4d7/0x900 kernel/locking/lockdep.c:3875
RSP: 0018:ffff88018a8270b0 EFLAGS: 00010a06
Kernel panic - not syncing: panic_on_warn set ...

RAX: 0000000000000000 RBX: ffff8801dad2cc40 RCX: 1bd5a00000000022
RDX: 00000000000005e7 RSI: ffffffff810f018e RDI: dead000000000110
RBP: ffff88018a827198 R08: ffff88019317a300 R09: fffff52001ca8c46
R10: fffff52001ca8c46 R11: ffffc9000e546237 R12: dffffc0000000000
R13: ffff8801c47c8280 R14: 0000000000000000 R15: dead000000000100
FS:  00007fae31360700(0000) GS:ffff8801dad00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d425000 CR3: 00000001d8312000 CR4: 00000000001426e0
Call Trace:
 context_switch kernel/sched/core.c:2833 [inline]
 __schedule+0x874/0x1ed0 kernel/sched/core.c:3479
 schedule+0xfe/0x460 kernel/sched/core.c:3523
 freezable_schedule include/linux/freezer.h:172 [inline]
 futex_wait_queue_me+0x3f9/0x840 kernel/futex.c:2530
 futex_wait+0x45c/0xa50 kernel/futex.c:2645
 do_futex+0x31a/0x26d0 kernel/futex.c:3528
 __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:00007fae3135fcf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 000000000072bfa8 RCX: 0000000000457679
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000072bfa8
RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000072bfac
R13: 00007fff13965f2f R14: 00007fae313609c0 R15: 0000000000000001
Modules linked in:
Kernel Offset: disabled
Rebooting in 86400 seconds..