general protection fault in unlink_anon_vmas

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f37e99ac Merge tag 's390-5.8-6' of git://git.kernel.org/pu..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10602a90900000
kernel config: https://syzkaller.appspot.com/x/.config?x=f87a5e4232fdb267
dashboard link: https://syzkaller.appspot.com/bug?extid=f86b1549602d33194e84
compiler: gcc (GCC) 10.1.0-syz 20200507
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linu...@kvack.org]

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+f86b15...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 32381 Comm: systemd-rfkill Not tainted 5.8.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:unlink_anon_vmas+0x1ca/0x830 mm/rmap.c:401
Code: 34 24 49 89 c5 e8 c6 9a cb ff 48 8d 7d 08 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 dc 04 00 00 4c 8b 65 08 4c 89 e0 48 c1 e8 03 <80> 3c 18 00 0f 85 ba 04 00 00 4d 8b 34 24 4c 3b 34 24 74 1e e8 8d
RSP: 0018:ffffc90004347bc8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffffff81a2cf6c
RDX: ffff88804d28e080 RSI: ffffffff81a821ca RDI: ffff888000134628
RBP: ffff888000134620 R08: 0000000000000001 R09: ffff88808855a9af
R10: 00007fc15bc9a000 R11: 0000000000000000 R12: 0000000000000000
R13: fffffffffffffff0 R14: 00007ffcebe3d000 R15: ffff888000134630
FS: 00007fc15bc888c0(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc159c78ab4 CR3: 00000000a3423000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
free_pgtables+0xe2/0x2f0 mm/memory.c:398
exit_mmap+0x2c0/0x510 mm/mmap.c:3151
__mmput+0x122/0x470 kernel/fork.c:1093
mmput+0x53/0x60 kernel/fork.c:1114
exit_mm kernel/exit.c:482 [inline]
do_exit+0xa8f/0x2a40 kernel/exit.c:792
do_group_exit+0x125/0x310 kernel/exit.c:903
__do_sys_exit_group kernel/exit.c:914 [inline]
__se_sys_exit_group kernel/exit.c:912 [inline]
__x64_sys_exit_group+0x3a/0x50 kernel/exit.c:912
do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fc15b351618
Code: Bad RIP value.
RSP: 002b:00007ffcebe5ce38 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc15b351618
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00007fc15b62e8e0 R08: 00000000000000e7 R09: fffffffffffffee8
R10: 00007fc15980c158 R11: 0000000000000246 R12: 00007fc15b62e8e0
R13: 00007fc15b633c20 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 3c1ee0c793606f16 ]---
RIP: 0010:unlink_anon_vmas+0x1ca/0x830 mm/rmap.c:401
Code: 34 24 49 89 c5 e8 c6 9a cb ff 48 8d 7d 08 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 dc 04 00 00 4c 8b 65 08 4c 89 e0 48 c1 e8 03 <80> 3c 18 00 0f 85 ba 04 00 00 4d 8b 34 24 4c 3b 34 24 74 1e e8 8d
RSP: 0018:ffffc90004347bc8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffffff81a2cf6c
RDX: ffff88804d28e080 RSI: ffffffff81a821ca RDI: ffff888000134628
RBP: ffff888000134620 R08: 0000000000000001 R09: ffff88808855a9af
R10: 00007fc15bc9a000 R11: 0000000000000000 R12: 0000000000000000
R13: fffffffffffffff0 R14: 00007ffcebe3d000 R15: ffff888000134630
FS: 00007fc15bc888c0(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc159c78ab4 CR3: 0000000093e93000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[syzbot]

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