Re: [syzbot] [netfs?] WARNING in netfs_writepages

[syzbot <syzbot+06023121b0153752a3d3@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    f486c8aa16b8 Add linux-next specific files for 20241128
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=136ba7c0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e348a4873516af92
dashboard link: https://syzkaller.appspot.com/bug?extid=06023121b0153752a3d3
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=119abf78580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1527dd30580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/beb58ebb63cf/disk-f486c8aa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b241b5609e64/vmlinux-f486c8aa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c9d817f665f2/bzImage-f486c8aa.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+06023121b0153752a3d3@syzkaller.appspotmail.com

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WARNING: CPU: 1 PID: 35 at fs/netfs/write_issue.c:583 netfs_writepages+0x8ff/0xb60 fs/netfs/write_issue.c:583
Modules linked in:
CPU: 1 UID: 0 PID: 35 Comm: kworker/u8:2 Not tainted 6.12.0-next-20241128-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: writeback wb_workfn (flush-9p-1)
RIP: 0010:netfs_writepages+0x8ff/0xb60 fs/netfs/write_issue.c:583
Code: 10 4c 89 f2 48 8d 4c 24 70 e8 ad a6 85 ff 48 85 c0 0f 84 e6 00 00 00 48 89 c3 e8 cc dc 49 ff e9 4a fe ff ff e8 c2 dc 49 ff 90 <0f> 0b 90 e9 a9 fe ff ff e8 b4 dc 49 ff 4c 89 e7 be 08 00 00 00 e8
RSP: 0018:ffffc90000ab70c0 EFLAGS: 00010293
RAX: ffffffff8255983e RBX: 810f000000000000 RCX: ffff888020a9da00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 810f000000000000
RBP: ffffc90000ab7190 R08: ffffffff825596e2 R09: 1ffff1100415a855
R10: dffffc0000000000 R11: ffffed100415a856 R12: ffff888020ad42d8
R13: dffffc0000000000 R14: ffffea0001b5e580 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f475ed5bd58 CR3: 00000000771b4000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 do_writepages+0x35f/0x880 mm/page-writeback.c:2702
 __writeback_single_inode+0x14f/0x10d0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x820/0x1360 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:2047
 wb_writeback+0x427/0xb80 fs/fs-writeback.c:2158
 wb_check_background_flush fs/fs-writeback.c:2228 [inline]
 wb_do_writeback fs/fs-writeback.c:2316 [inline]
 wb_workfn+0xc4b/0x1080 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>


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