Re: [syzbot] [mm?] WARNING in move_to_new_folio (2)

[Zi Yan <ziy@nvidia.com>]

On 8 Jul 2025, at 13:51, syzbot wrote:

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    d7b8f8e20813 Linux 6.16-rc5
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=16ff728c580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f6cfc97245100778
> dashboard link: https://syzkaller.appspot.com/bug?extid=3a24467a5470194c4175
> compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=132adf70580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11ff728c580000
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-d7b8f8e2.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/88e0e9607487/vmlinux-d7b8f8e2.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/c0e31868d902/bzImage-d7b8f8e2.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/02a26963f634/mount_0.gz
>   fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=150e5582580000)
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+3a24467a5470194c4175@syzkaller.appspotmail.com
>
> ------------[ cut here ]------------
> gfs2_meta_aops does not implement migrate_folio

This warning is intended to make fs (e.g., gfs2) implement migrate_folio()
in their aops. gfs2_meta_aops and gfs2_rgrp_aops need the change.

Should we change syzbot subsystem to fs?

> WARNING: CPU: 0 PID: 30 at mm/migrate.c:944 fallback_migrate_folio mm/migrate.c:942 [inline]
> WARNING: CPU: 0 PID: 30 at mm/migrate.c:944 move_to_new_folio+0x696/0x7a0 mm/migrate.c:996
> Modules linked in:
> CPU: 0 UID: 0 PID: 30 Comm: kcompactd1 Not tainted 6.16.0-rc5-syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> RIP: 0010:fallback_migrate_folio mm/migrate.c:942 [inline]
> RIP: 0010:move_to_new_folio+0x696/0x7a0 mm/migrate.c:996
> Code: 0d 01 90 42 80 7c 3d 00 00 74 0a 48 8b 7c 24 20 e8 3f 53 fe ff 48 8b 44 24 20 48 8b 30 48 c7 c7 80 b4 97 8b e8 bb b0 5e ff 90 <0f> 0b 90 90 49 bf 00 00 00 00 00 fc ff df e9 7e fd ff ff e8 62 d0
> RSP: 0018:ffffc900005171d0 EFLAGS: 00010246
> RAX: 07a7b0ed2cfb0500 RBX: ffffea0000fecc00 RCX: ffff888030f20000
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
> RBP: 1ffff1100a4b8921 R08: ffff88801fc24293 R09: 1ffff11003f84852
> R10: dffffc0000000000 R11: ffffed1003f84853 R12: ffffea00012c1a80
> R13: ffff8880525c47e8 R14: ffffea0000fecc08 R15: dffffc0000000000
> FS:  0000000000000000(0000) GS:ffff88808d21d000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000c0000cc000 CR3: 000000003fab7000 CR4: 0000000000352ef0
> Call Trace:
>  <TASK>
>  migrate_folio_move mm/migrate.c:1301 [inline]
>  migrate_folios_move mm/migrate.c:1653 [inline]
>  migrate_pages_batch+0x1c34/0x2830 mm/migrate.c:1900
>  migrate_pages_sync mm/migrate.c:1930 [inline]
>  migrate_pages+0x1bcc/0x2930 mm/migrate.c:2039
>  compact_zone+0x23f4/0x4ad0 mm/compaction.c:2683
>  kcompactd_do_work mm/compaction.c:3134 [inline]
>  kcompactd+0x97d/0x1290 mm/compaction.c:3228
>  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:
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>
> If the report is already addressed, let syzbot know by replying with:
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>
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
>
> 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


Best Regards,
Yan, Zi