general protection fault in page_vma_mapped_walk

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: e1f7d50a Linux 4.14.160
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15210a3ee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=46599517442ad9fb
dashboard link: https://syzkaller.appspot.com/bug?extid=db25f3a705dff6a22bea
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+db25f3...@syzkaller.appspotmail.com

kobject: 'loop4' (ffff8880a414c560): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop2' (ffff8880a40b4d20): kobject_uevent_env
kobject: 'loop2' (ffff8880a40b4d20): fill_kobj_path: path
= '/devices/virtual/block/loop2'
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: 1445 Comm: kswapd0 Not tainted 4.14.160-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8880a66e6480 task.stack: ffff8880a66a0000
RIP: 0010:page_vma_mapped_walk+0x4ff/0x1cc0 mm/page_vma_mapped.c:171
RSP: 0018:ffff8880a66a7508 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff8880a66a75f0 RCX: ffff8880a66a7780
RDX: 0000000000000000 RSI: ffff88808327f358 RDI: ffff888000132d50
RBP: ffff8880a66a7588 R08: ffff8880a66e6480 R09: 0000000000000001
R10: 0000000000000000 R11: ffff8880a66e6480 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880a66a7650 R15: 0000000000476000
FS: 0000000000000000(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32f37000 CR3: 0000000210e93000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
page_referenced_one+0x1a6/0x500 mm/rmap.c:764
rmap_walk_file+0x38d/0x8b0 mm/rmap.c:1829
rmap_walk+0xed/0x190 mm/rmap.c:1847
page_referenced+0x3e7/0x4e0 mm/rmap.c:874
shrink_active_list+0x52c/0xd60 mm/vmscan.c:2049
shrink_list mm/vmscan.c:2173 [inline]
shrink_node_memcg+0xc03/0x11c0 mm/vmscan.c:2442
shrink_node+0x303/0xc40 mm/vmscan.c:2634
kswapd_shrink_node mm/vmscan.c:3296 [inline]
balance_pgdat mm/vmscan.c:3402 [inline]
kswapd+0x8fb/0x1600 mm/vmscan.c:3620
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 6b 12 00 00 48 8b 45 b0 4d 89 fc 49 c1 ec 24 41 81 e4 f8 0f 00 00 4c
03 60 50 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00
0f 85 1f 12 00 00 4d 8b 24 24 41 f6 c4 01 75 08 45
RIP: page_vma_mapped_walk+0x4ff/0x1cc0 mm/page_vma_mapped.c:171 RSP:
ffff8880a66a7508
---[ end trace 6277236fb1c516b1 ]---


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[syzbot]

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