[syzbot] [netfs?] WARNING in netfs_writepages (2)

[syzbot <syzbot+b3b2525cb55ad5a59499@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    038d61fd6422 Linux 6.16
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=104e0434580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=515ec0b49771bcd1
dashboard link: https://syzkaller.appspot.com/bug?extid=b3b2525cb55ad5a59499
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/34e894532715/disk-038d61fd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b6a27a46b9dc/vmlinux-038d61fd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f97a9c8d8216/bzImage-038d61fd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b3b2525cb55ad5a59499@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 12 at fs/netfs/write_issue.c:587 netfs_writepages+0x613/0x900 fs/netfs/write_issue.c:587
Modules linked in:
CPU: 0 UID: 0 PID: 12 Comm: kworker/u8:0 Not tainted 6.16.0-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-9p-7)
RIP: 0010:netfs_writepages+0x613/0x900 fs/netfs/write_issue.c:587
Code: df e8 b1 c0 b9 ff 49 c1 e6 0c 4c 8b 2b 4c 89 f7 4c 89 ee e8 bf db 59 ff 4d 39 ee 7c 07 e8 55 d9 59 ff eb 10 e8 4e d9 59 ff 90 <0f> 0b 90 eb 05 e8 43 d9 59 ff 4d 8d 74 24 28 4c 89 f0 48 c1 e8 03
RSP: 0018:ffffc900001170c0 EFLAGS: 00010293
RAX: ffffffff82664c72 RBX: ffff888058820280 RCX: ffff88801d2a5a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 810f000000000000
RBP: ffffc900001171c0 R08: ffff888058820287 R09: 1ffff1100b104050
R10: dffffc0000000000 R11: ffffed100b104051 R12: ffffea00004766c0
R13: 0000000000000000 R14: 810f000000000000 R15: ffff888057520498
FS:  0000000000000000(0000) GS:ffff888125c57000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000059812000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 do_writepages+0x32b/0x550 mm/page-writeback.c:2636
 __writeback_single_inode+0x145/0xff0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x6b5/0x1000 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2047
 wb_writeback+0x44f/0xaf0 fs/fs-writeback.c:2158
 wb_check_start_all fs/fs-writeback.c:2284 [inline]
 wb_do_writeback fs/fs-writeback.c:2310 [inline]
 wb_workfn+0x90b/0xef0 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup