general protection fault in mm_release

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cf256fbc Linux 4.14.231
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17695729d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=403e68efdb1dcca6
dashboard link: https://syzkaller.appspot.com/bug?extid=17d92e9074b308040148

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+17d92e...@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
Modules linked in:
CPU: 1 PID: 29575 Comm: syz-executor.4 Not tainted 4.14.231-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888000124440 task.stack: ffff888220408000
RIP: 0010:__lock_acquire+0x1cc/0x3f20 kernel/locking/lockdep.c:3369
RSP: 0018:ffff88822040fb20 EFLAGS: 00010002
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 00e000e0e0000004 RSI: 0000000000000000 RDI: 0700070700000020
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: ffff888000124440 R12: 0700070700000020
R13: 0000000000000000 R14: 0000000000000001 R15: ffffffff8bebbd40
FS: 0000000000000000(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000203b2000 CR3: 0000000227303000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:160
complete+0x13/0x70 kernel/sched/completion.c:35
complete_vfork_done kernel/fork.c:1098 [inline]
mm_release+0x1a4/0x2d0 kernel/fork.c:1166
exit_mm kernel/exit.c:500 [inline]
do_exit+0x56f/0x2850 kernel/exit.c:855
do_group_exit+0x100/0x2e0 kernel/exit.c:965
SYSC_exit_group kernel/exit.c:976 [inline]
SyS_exit_group+0x19/0x20 kernel/exit.c:974
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x466459
RSP: 002b:00007ffc813b8f88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000000000000001e RCX: 0000000000466459
RDX: 000000000041926b RSI: ffffffffffffffbc RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000001 R15: 00007ffc813b9080
Code: 18 00 00 00 00 48 81 c4 80 01 00 00 44 89 e8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 0f 85 67 2a 00 00 49 81 3c 24 a0 77 2e 8b 0f 84 5f
RIP: __lock_acquire+0x1cc/0x3f20 kernel/locking/lockdep.c:3369 RSP: ffff88822040fb20
---[ end trace b0ae52f5c72991ac ]---


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[syzbot]

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