[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+dbc44f...@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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