BUG: unable to handle kernel paging request in kernel_get_mempolicy

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    bef7b2a7 Merge tag 'devicetree-for-5.7' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13966e8fe00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=91b674b8f0368e69
dashboard link: https://syzkaller.appspot.com/bug?extid=693dc11fcb53120b5559
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1738b02be00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17d2c76de00000

The bug was bisected to:

commit 4426e945df588f2878affddf88a51259200f7e29
Author: Peter Xu <peterx@xxxxxxxxxx>
Date:   Thu Apr 2 04:08:49 2020 +0000

    mm/gup: allow VM_FAULT_RETRY for multiple times

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=14ac4a5de00000
final crash:    https://syzkaller.appspot.com/x/report.txt?x=16ac4a5de00000
console output: https://syzkaller.appspot.com/x/log.txt?x=12ac4a5de00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+693dc11fcb53120b5559@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 4426e945df58 ("mm/gup: allow VM_FAULT_RETRY for multiple times")

BUG: unable to handle page fault for address: ffffffff00000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 987c067 P4D 987c067 PUD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7181 Comm: syz-executor616 Not tainted 5.6.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:page_to_nid include/linux/mm.h:1245 [inline]
RIP: 0010:lookup_node mm/mempolicy.c:906 [inline]
RIP: 0010:do_get_mempolicy mm/mempolicy.c:970 [inline]
RIP: 0010:kernel_get_mempolicy+0x60e/0xfb0 mm/mempolicy.c:1615
Code: 88 00 07 00 00 e8 b2 35 c5 ff 4c 8b 7c 24 78 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 fb 08 00 00 <49> 8b 1f 48 c7 c7 ff ff ff ff 48 89 de e8 10 37 c5 ff 48 83 fb ff
RSP: 0018:ffffc900018d7de8 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81adaaf1
RDX: 1fffffffe0000000 RSI: ffffffff81adaafe RDI: 0000000000000005
RBP: 0000000000000000 R08: ffff88808de924c0 R09: ffffed1011bd2499
R10: ffff88808de924c7 R11: ffffed1011bd2498 R12: 0000000000000000
R13: 1ffff9200031afc4 R14: ffffffff89a6df60 R15: ffffffff00000000
FS:  00007f848cd4a700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffff00000000 CR3: 00000000a7a8d000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __do_sys_get_mempolicy mm/mempolicy.c:1633 [inline]
 __se_sys_get_mempolicy mm/mempolicy.c:1629 [inline]
 __x64_sys_get_mempolicy+0xba/0x150 mm/mempolicy.c:1629
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x446719
Code: e8 5c b3 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f848cd49db8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ef
RAX: ffffffffffffffda RBX: 00000000006dbc28 RCX: 0000000000446719
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00000000006dbc20 R08: 0000000000000003 R09: 0000000000000000
R10: 000000002073b000 R11: 0000000000000246 R12: 00000000006dbc2c
R13: 00007ffcfe6ba66f R14: 00007f848cd4a9c0 R15: 20c49ba5e353f7cf
Modules linked in:
CR2: ffffffff00000000
---[ end trace 0becf554e06291c3 ]---
RIP: 0010:page_to_nid include/linux/mm.h:1245 [inline]
RIP: 0010:lookup_node mm/mempolicy.c:906 [inline]
RIP: 0010:do_get_mempolicy mm/mempolicy.c:970 [inline]
RIP: 0010:kernel_get_mempolicy+0x60e/0xfb0 mm/mempolicy.c:1615
Code: 88 00 07 00 00 e8 b2 35 c5 ff 4c 8b 7c 24 78 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 fb 08 00 00 <49> 8b 1f 48 c7 c7 ff ff ff ff 48 89 de e8 10 37 c5 ff 48 83 fb ff
RSP: 0018:ffffc900018d7de8 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81adaaf1
RDX: 1fffffffe0000000 RSI: ffffffff81adaafe RDI: 0000000000000005
RBP: 0000000000000000 R08: ffff88808de924c0 R09: ffffed1011bd2499
R10: ffff88808de924c7 R11: ffffed1011bd2498 R12: 0000000000000000
R13: 1ffff9200031afc4 R14: ffffffff89a6df60 R15: ffffffff00000000
FS:  00007f848cd4a700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffff00000000 CR3: 00000000a7a8d000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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