[syzbot] [netfs?] WARNING in netfs_pages_written_back

[syzbot] [netfs?] WARNING in netfs_pages_written_back

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    e33c4963bf53 Merge tag 'nfsd-6.9-5' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=118f2c08980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=19891bd776e81b8b
dashboard link: https://syzkaller.appspot.com/bug?extid=dbc44fd848d570fc1526
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-e33c4963.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/af334172fdbc/vmlinux-e33c4963.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9c0bfbadd1ab/bzImage-e33c4963.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dbc44fd848d570fc1526@syzkaller.appspotmail.com

------------[ cut here ]------------
bad 1 @0 page 0 0
WARNING: CPU: 0 PID: 14804 at fs/netfs/buffered_write.c:653 netfs_pages_written_back+0xe02/0x1320 fs/netfs/buffered_write.c:653
Modules linked in:
CPU: 0 PID: 14804 Comm: syz-executor.2 Not tainted 6.9.0-rc5-syzkaller-00053-ge33c4963bf53 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:netfs_pages_written_back+0xe02/0x1320 fs/netfs/buffered_write.c:653
Code: 48 c1 ee 03 80 3c 06 00 0f 85 d0 04 00 00 48 8b 44 24 18 4d 89 f0 48 c7 c7 80 54 22 8b 48 8b b0 28 01 00 00 e8 8f 0a 21 ff 90 <0f> 0b 90 90 e9 3c f4 ff ff e8 c0 35 5e ff e8 9b cc 44 ff 31 ff 41
RSP: 0018:ffffc900030a75b8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffffea0001522140 RCX: ffffffff81513b29
RDX: ffff88801e1c2440 RSI: ffffffff81513b36 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000003 R12: dffffc0000000000
R13: ffff88801fa60040 R14: 0000000000000000 R15: ffff88801fa60138
FS:  0000000000000000(0000) GS:ffff88802c200000(0063) knlGS:00000000f5ed1b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000eda8fda4 CR3: 00000000468b6000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 00000000872c9164 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 netfs_cleanup_buffered_write+0x7a8/0x9b0 fs/netfs/buffered_write.c:726
 netfs_write_terminated+0x3c7/0x910 fs/netfs/output.c:121
 netfs_end_writethrough+0x1a6/0x200 fs/netfs/output.c:468
 netfs_perform_write+0x1a6c/0x26b0 fs/netfs/buffered_write.c:398
 netfs_buffered_write_iter_locked+0x213/0x2c0 fs/netfs/buffered_write.c:454
 netfs_file_write_iter+0x1e0/0x470 fs/netfs/buffered_write.c:493
 v9fs_file_write_iter+0xa1/0x100 fs/9p/vfs_file.c:407
 call_write_iter include/linux/fs.h:2110 [inline]
 do_iter_readv_writev+0x504/0x780 fs/read_write.c:741
 vfs_writev+0x36f/0xdb0 fs/read_write.c:971
 do_pwritev+0x1b2/0x260 fs/read_write.c:1072
 __do_compat_sys_pwritev2 fs/read_write.c:1218 [inline]
 __se_compat_sys_pwritev2 fs/read_write.c:1210 [inline]
 __ia32_compat_sys_pwritev2+0x121/0x1b0 fs/read_write.c:1210
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7300579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5ed15ac EFLAGS: 00000292 ORIG_RAX: 000000000000017b
RAX: ffffffffffffffda RBX: 0000000000000026 RCX: 0000000020000240
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000015 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	10 06                	adc    %al,(%rsi)
   2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
   6:	10 07                	adc    %al,(%rdi)
   8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
   c:	10 08                	adc    %cl,(%rax)
   e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1e:	00 51 52             	add    %dl,0x52(%rcx)
  21:	55                   	push   %rbp
  22:	89 e5                	mov    %esp,%ebp
  24:	0f 34                	sysenter
  26:	cd 80                	int    $0x80
* 28:	5d                   	pop    %rbp <-- trapping instruction
  29:	5a                   	pop    %rdx
  2a:	59                   	pop    %rcx
  2b:	c3                   	ret
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	90                   	nop
  2f:	90                   	nop
  30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi


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