general protection fault in unlink_anon_vmas

[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=15ec9b6dd00000
kernel config: https://syzkaller.appspot.com/x/.config?x=403e68efdb1dcca6
dashboard link: https://syzkaller.appspot.com/bug?extid=91fc0a6a17194c8de1bb

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+91fc0a...@syzkaller.appspotmail.com

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: 0 PID: 17214 Comm: syz-executor.5 Not tainted 4.14.231-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888000052280 task.stack: ffff888000058000
RIP: 0010:unlink_anon_vmas+0x63/0x7e0 mm/rmap.c:385
RSP: 0018:ffff88800005f8f8 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffff88800010bd68
RBP: fffffffffffffff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 00007f25a8199000 R14: 00007f25a8177000 R15: 0000000000000000
FS: 00007f25a8197700(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000014a53ad CR3: 000000009e276000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
free_pgtables+0x178/0x2b0 mm/memory.c:655
exit_mmap+0x27f/0x4d0 mm/mmap.c:3059
__mmput kernel/fork.c:930 [inline]
mmput kernel/fork.c:951 [inline]
mmput+0xfa/0x420 kernel/fork.c:946
exit_mm kernel/exit.c:548 [inline]
do_exit+0x984/0x2850 kernel/exit.c:855
do_group_exit+0x100/0x2e0 kernel/exit.c:965
get_signal+0x38d/0x1ca0 kernel/signal.c:2423
do_signal+0x7c/0x1550 arch/x86/kernel/signal.c:792
exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4665f9
RSP: 002b:00007f25a8197218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000056bf68 RCX: 00000000004665f9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000056bf68
RBP: 000000000056bf60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf6c
R13: 00007ffc37d840bf R14: 00007f25a8197300 R15: 0000000000022000
Code: 80 3c 02 00 0f 85 f9 06 00 00 48 8b 44 24 10 48 8b 58 78 48 b8 00 00 00 00 00 fc ff df 48 8d 6b f0 48 89 da 49 89 df 48 c1 ea 03 <80> 3c 02 00 0f 85 c1 06 00 00 48 8b 03 48 39 5c 24 08 4c 8d 68
RIP: unlink_anon_vmas+0x63/0x7e0 mm/rmap.c:385 RSP: ffff88800005f8f8
---[ end trace b0a63bafc07f4757 ]---


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[syzbot]

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