general protection fault in pick_next_task_fair

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 311ef88a Add linux-next specific files for 20191004
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=126a2f25600000
kernel config: https://syzkaller.appspot.com/x/.config?x=db2e4361e48662f4
dashboard link: https://syzkaller.appspot.com/bug?extid=ad270ac7d05a2489aaf1
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [linux-...@vger.kernel.org tg...@linutronix.de]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ad270a...@syzkaller.appspotmail.com

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: 9691 Comm: syz-executor.2 Not tainted 5.4.0-rc1-next-20191004 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:pick_next_task_fair+0x1ae/0xc60 kernel/sched/fair.c:6788
Code: ff e8 b6 20 ff ff 84 c0 0f 85 95 00 00 00 4c 89 fe 4c 89 e7 e8 a3 61
fd ff 48 8d b8 60 01 00 00 49 89 c7 48 89 fa 48 c1 ea 03 <80> 3c 1a 00 0f
85 8c 08 00 00 4d 8b a7 60 01 00 00 4d 85 e4 0f 84
RSP: 0018:ffff88805cc5fb18 EFLAGS: 00010002
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 000000000000002c RSI: 0000000000000000 RDI: 0000000000000160
RBP: ffff88805cc5fb70 R08: ffff888058f080b8 R09: ffff888096c52810
R10: ffff888096c52840 R11: ffff888096c52990 R12: ffff8880ae834d80
R13: ffff88805cc5fbe0 R14: ffff888058f08040 R15: 0000000000000000
FS: 00000000011bd940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ef2b000 CR3: 000000009a2e2000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
pick_next_task kernel/sched/core.c:3920 [inline]
__schedule+0x3d0/0x1e70 kernel/sched/core.c:4039
schedule+0xd9/0x260 kernel/sched/core.c:4136
freezable_schedule include/linux/freezer.h:172 [inline]
do_nanosleep+0x21f/0x640 kernel/time/hrtimer.c:1871
hrtimer_nanosleep+0x297/0x550 kernel/time/hrtimer.c:1924
__do_sys_nanosleep kernel/time/hrtimer.c:1958 [inline]
__se_sys_nanosleep kernel/time/hrtimer.c:1945 [inline]
__x64_sys_nanosleep+0x1a6/0x220 kernel/time/hrtimer.c:1945
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457f21
Code: 75 14 b8 23 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 24 d3 fb ff c3 48
83 ec 08 e8 ea 46 00 00 48 89 04 24 b8 23 00 00 00 0f 05 <48> 8b 3c 24 48
89 c2 e8 33 47 00 00 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fff217f7b00 EFLAGS: 00000293 ORIG_RAX: 0000000000000023
RAX: ffffffffffffffda RBX: 00000000000387e9 RCX: 0000000000457f21
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007fff217f7b10
RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff
R10: 00007fff217f7c00 R11: 0000000000000293 R12: 000000000075bf20
R13: 000000000075c9a0 R14: 00000000007601a8 R15: 000000000075bf2c
Modules linked in:

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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.