general protection fault in page_vma_mapped_walk

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5191249f8803 Add linux-next specific files for 20211118
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15428c4eb00000
kernel config: https://syzkaller.appspot.com/x/.config?x=fca39774e64812b0
dashboard link: https://syzkaller.appspot.com/bug?extid=9e8fc6d95f32c64ce562
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
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+9e8fc6...@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: 1 PID: 8 Comm: kworker/u4:0 Not tainted 5.16.0-rc1-next-20211118-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn (flush-8:0)
RIP: 0010:page_vma_mapped_walk+0x7ff/0x24d0 mm/page_vma_mapped.c:203
Code: 8b 44 24 10 80 38 00 0f 85 f8 15 00 00 48 8b 44 24 20 4c 89 f5 48 c1 ed 24 81 e5 f8 0f 00 00 48 03 68 50 48 89 e8 48 c1 e8 03 <42> 80 3c 38 00 0f 85 df 15 00 00 48 8b 6d 00 31 ff 41 89 ec 41 83
RSP: 0018:ffffc90000cd6d70 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffc90000cd6eb0 RCX: 0000000000000000
RDX: ffff888010e7d7c0 RSI: ffffffff81b0ec14 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff81b0e5d8 R11: 0000000000000000 R12: 0000000000000000
R13: 0000001b31d23000 R14: 0000001b31d23000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f651b7bb718 CR3: 0000000018ad7000 CR4: 00000000003526e0
Call Trace:
<TASK>
page_mkclean_one+0x44c/0x8c0 mm/rmap.c:923
rmap_walk_file+0x3a5/0x6e0 mm/rmap.c:2356
rmap_walk+0x10d/0x190 mm/rmap.c:2374
folio_mkclean+0x174/0x1a0 mm/rmap.c:1003
folio_clear_dirty_for_io+0x149/0x790 mm/page-writeback.c:2757
mpage_submit_page+0x80/0x2a0 fs/ext4/inode.c:2075
mpage_process_page_bufs+0x681/0x7a0 fs/ext4/inode.c:2209
mpage_prepare_extent_to_map+0x94f/0xe60 fs/ext4/inode.c:2621
ext4_writepages+0x926/0x3b90 fs/ext4/inode.c:2749
do_writepages+0x1ab/0x690 mm/page-writeback.c:2364
__writeback_single_inode+0x126/0xff0 fs/fs-writeback.c:1616
writeback_sb_inodes+0x53d/0xf30 fs/fs-writeback.c:1881
__writeback_inodes_wb+0xc6/0x280 fs/fs-writeback.c:1951
wb_writeback+0x7f8/0xc30 fs/fs-writeback.c:2056
wb_check_old_data_flush fs/fs-writeback.c:2156 [inline]
wb_do_writeback fs/fs-writeback.c:2209 [inline]
wb_workfn+0x8cf/0x12d0 fs/fs-writeback.c:2238
process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298
worker_thread+0x658/0x11f0 kernel/workqueue.c:2445
kthread+0x405/0x4f0 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Modules linked in:
---[ end trace 1ebc282721e655c5 ]---
RIP: 0010:page_vma_mapped_walk+0x7ff/0x24d0 mm/page_vma_mapped.c:203
Code: 8b 44 24 10 80 38 00 0f 85 f8 15 00 00 48 8b 44 24 20 4c 89 f5 48 c1 ed 24 81 e5 f8 0f 00 00 48 03 68 50 48 89 e8 48 c1 e8 03 <42> 80 3c 38 00 0f 85 df 15 00 00 48 8b 6d 00 31 ff 41 89 ec 41 83
RSP: 0018:ffffc90000cd6d70 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffc90000cd6eb0 RCX: 0000000000000000
RDX: ffff888010e7d7c0 RSI: ffffffff81b0ec14 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff81b0e5d8 R11: 0000000000000000 R12: 0000000000000000
R13: 0000001b31d23000 R14: 0000001b31d23000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6269627718 CR3: 000000006d963000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 8b 44 24 10 mov 0x10(%rsp),%eax
4: 80 38 00 cmpb $0x0,(%rax)
7: 0f 85 f8 15 00 00 jne 0x1605
d: 48 8b 44 24 20 mov 0x20(%rsp),%rax
12: 4c 89 f5 mov %r14,%rbp
15: 48 c1 ed 24 shr $0x24,%rbp
19: 81 e5 f8 0f 00 00 and $0xff8,%ebp
1f: 48 03 68 50 add 0x50(%rax),%rbp
23: 48 89 e8 mov %rbp,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1) <-- trapping instruction
2f: 0f 85 df 15 00 00 jne 0x1614
35: 48 8b 6d 00 mov 0x0(%rbp),%rbp
39: 31 ff xor %edi,%edi
3b: 41 89 ec mov %ebp,%r12d
3e: 41 rex.B
3f: 83 .byte 0x83


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[syzbot]

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