Re: [syzbot] [netfs?] WARNING in netfs_writepages (3)

Re: [syzbot] [netfs?] WARNING in netfs_writepages (3)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+0da43efa72f88bd3a8af@syzkaller.appspotmail.com
Tested-by: syzbot+0da43efa72f88bd3a8af@syzkaller.appspotmail.com

Tested on:

commit:         0e35b9b6 Merge tag 'mm-hotfixes-stable-2026-07-06-17-4..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=147f4589580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=48ef5c5c0f192153
dashboard link: https://syzkaller.appspot.com/bug?extid=0da43efa72f88bd3a8af
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1338ab39580000

Note: testing is done by a robot and is best-effort only.

[syzbot] [netfs?] WARNING in netfs_writepages (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    7404ce516372 Merge tag 's390-7.2-3' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=119f1661580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=48ef5c5c0f192153
dashboard link: https://syzkaller.appspot.com/bug?extid=0da43efa72f88bd3a8af
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1727ebde580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=172dbec1580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-7404ce51.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e63433d84892/vmlinux-7404ce51.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7542fae0615e/bzImage-7404ce51.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0da43efa72f88bd3a8af@syzkaller.appspotmail.com

R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fe029a25fac R14: 00007fe029a25fa0 R15: 00007fe029a25fa0
 </TASK>
------------[ cut here ]------------
folio != NULL
WARNING: fs/netfs/write_issue.c:603 at netfs_writepages+0x883/0xa10 fs/netfs/write_issue.c:603, CPU#3: syz.0.17/5919
Modules linked in:
CPU: 3 UID: 0 PID: 5919 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:netfs_writepages+0x883/0xa10 fs/netfs/write_issue.c:603
Code: 48 89 df e8 3f 8b 7b ff 48 8b 4c 24 08 48 89 da 4c 89 e6 4c 89 f7 e8 ec 34 7f ff 48 85 c0 0f 84 c1 fe ff ff e8 0e c7 3d ff 90 <0f> 0b 90 e9 b3 fe ff ff e8 00 c7 3d ff 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc9000415f178 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffea00014f2580 RCX: ffffffff824b4bda
RDX: ffff88802bcea540 RSI: ffffffff82cc0992 RDI: ffff88802bcea540
RBP: fffffffffffffff4 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffc9000415f348
R13: ffff888046848bc0 R14: ffff888046848dd8 R15: dffffc0000000000
FS:  0000555567857500(0000) GS:ffff8880d60ec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000002901 CR3: 0000000025ac6000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 do_writepages+0x278/0x600 mm/page-writeback.c:2571
 filemap_writeback+0x22d/0x2e0 mm/filemap.c:387
 v9fs_mmap_vm_close fs/9p/vfs_file.c:496 [inline]
 v9fs_mmap_vm_close+0x137/0x1e0 fs/9p/vfs_file.c:489
 vma_close mm/internal.h:190 [inline]
 vms_clean_up_area mm/vma.c:1318 [inline]
 __mmap_setup mm/vma.c:2476 [inline]
 __mmap_region+0x890/0x2db0 mm/vma.c:2756
 mmap_region+0x527/0x620 mm/vma.c:2860
 do_mmap+0xc63/0x12f0 mm/mmap.c:560
 vm_mmap_pgoff+0x29e/0x470 mm/util.c:581
 ksys_mmap_pgoff+0x3cb/0x610 mm/mmap.c:606
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe02979de59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff3ad0a858 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fe029a25fa0 RCX: 00007fe02979de59
RDX: 0000000000000002 RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007fff3ad0a8c0 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fe029a25fac R14: 00007fe029a25fa0 R15: 00007fe029a25fa0
 </TASK>


---
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