general protection fault in mm_update_next_owner

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: c04fc6fa Linux 4.14.165
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15763eaee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=d36f53294bbc71f0
dashboard link: https://syzkaller.appspot.com/bug?extid=ca9e6e1b6d56d6d093f3
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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+ca9e6e...@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 4705 Comm: syz-executor.1 Not tainted 4.14.165-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff88801e9b6580 task.stack: ffff8881ff230000
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:mm_update_next_owner+0x37d/0x5d0 kernel/exit.c:451
RSP: 0018:ffff8881ff237d20 EFLAGS: 00010202
RAX: 0000000000000002 RBX: dffffc0000000000 RCX: 00000000026b904f
RDX: 0000000000000000 RSI: 0000000000000200 RDI: ffff888000122940
RBP: ffff8881ff237d80 R08: ffff8880867545f0 R09: ffffffff89571fc8
R10: ffff88801e9b6e00 R11: ffff88801e9b6580 R12: 0000000000000000
R13: ffff888053f9d940 R14: ffff888068dd6d00 R15: ffff88801e9b6580
FS: 0000000000000000(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020d30000 CR3: 000000005a606000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
exit_mm kernel/exit.c:544 [inline]
do_exit+0x94a/0x2cd0 kernel/exit.c:845
do_group_exit+0x111/0x330 kernel/exit.c:955
SYSC_exit_group kernel/exit.c:966 [inline]
SyS_exit_group+0x1d/0x20 kernel/exit.c:964
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45af49
RSP: 002b:00007ffdc5291fb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000000000000001e RCX: 000000000045af49
RDX: 0000000000414ae1 RSI: fffffffffffffff7 RDI: 0000000000000000
RBP: 0000000000000000 R08: 000000006e783fbf R09: 00007ffdc5292010
R10: 000000006e783fbb R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffdc5292010 R14: 0000000000000000 R15: 00007ffdc5292020
Code: 24 20 03 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 01 02 00 00 4d
8b a4 24 20 03 00 00 49 8d 44 24 10 48 89 45 d0 48 c1 e8 03 <80> 3c 18 00
0f 85 d4 01 00 00 49 8b 44 24 10 48 39 45 d0 4c 8d
RIP: __read_once_size include/linux/compiler.h:183 [inline] RSP:
ffff8881ff237d20
RIP: mm_update_next_owner+0x37d/0x5d0 kernel/exit.c:451 RSP:
ffff8881ff237d20
---[ end trace 5a96c4fc321af7ed ]---


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

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