linux-kernel - Re: [syzbot] [mm?] WARNING in move_page

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Message-ID: <664ea661-081a-4040-96c4-26307ba020ed@lucifer.local>
Date: Wed, 13 Aug 2025 05:47:52 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: syzbot <syzbot+4d9a13f0797c46a29e42@...kaller.appspotmail.com>
Cc: Liam.Howlett@...cle.com, akpm@...ux-foundation.org, jannh@...gle.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org, pfalcato@...e.de,
        syzkaller-bugs@...glegroups.com, vbabka@...e.cz
Subject: Re: [syzbot] [mm?] WARNING in move_page_tables

On Tue, Aug 12, 2025 at 02:56:35PM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    53e760d89498 Merge tag 'nfsd-6.17-1' of git://git.kernel.o..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=165fe9a2580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f9319a42cfb3bf57
> dashboard link: https://syzkaller.appspot.com/bug?extid=4d9a13f0797c46a29e42
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14172842580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15b04c34580000
>

As usual the repro doesn't repro for me.

Let's try [0] as a quick check as upstream doesn't have it yet.

[0]:https://lore.kernel.org/all/20250806145611.3962-1-dev.jain@arm.com/

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-hotfixes-unstable

> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-53e760d8.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/584b4139c7e3/vmlinux-53e760d8.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/4d2474607300/bzImage-53e760d8.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+4d9a13f0797c46a29e42@...kaller.appspotmail.com
>
> R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000002
> R13: 00007f00d0db5fa0 R14: 00007f00d0db5fa0 R15: 0000000000000005
>  </TASK>
> ------------[ cut here ]------------
> WARNING: CPU: 2 PID: 6133 at mm/mremap.c:357 move_normal_pmd mm/mremap.c:357 [inline]
> WARNING: CPU: 2 PID: 6133 at mm/mremap.c:357 move_pgt_entry mm/mremap.c:595 [inline]
> WARNING: CPU: 2 PID: 6133 at mm/mremap.c:357 move_page_tables+0x3832/0x44a0 mm/mremap.c:852
> Modules linked in:
> CPU: 2 UID: 0 PID: 6133 Comm: syz.0.19 Not tainted 6.17.0-rc1-syzkaller-00004-g53e760d89498 #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:move_normal_pmd mm/mremap.c:357 [inline]
> RIP: 0010:move_pgt_entry mm/mremap.c:595 [inline]
> RIP: 0010:move_page_tables+0x3832/0x44a0 mm/mremap.c:852
> Code: 02 00 0f 85 b6 03 00 00 48 8b 2b 4c 89 f6 48 89 ef e8 e2 1b af ff 49 39 ee 0f 82 d5 cb ff ff e9 0c cc ff ff e8 1f 21 af ff 90 <0f> 0b 90 48 8b 44 24 40 48 8d 78 40 48 b8 00 00 00 00 00 fc ff df
> RSP: 0018:ffffc900037a76d8 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: 0000000032930007 RCX: ffffffff820c6645
> RDX: ffff88802e56a440 RSI: ffffffff820c7201 RDI: 0000000000000007
> RBP: ffff888037728fc0 R08: 0000000000000007 R09: 0000000000000000
> R10: 0000000032930007 R11: 0000000000000000 R12: 0000000000000000
> R13: ffffc900037a79a8 R14: 0000000000000001 R15: dffffc0000000000
> FS:  000055556316a500(0000) GS:ffff8880d68bc000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000001b30863fff CR3: 0000000050171000 CR4: 0000000000352ef0
> Call Trace:
>  <TASK>
>  copy_vma_and_data+0x468/0x790 mm/mremap.c:1215
>  move_vma+0x548/0x1780 mm/mremap.c:1282
>  mremap_to+0x1b7/0x450 mm/mremap.c:1406
>  do_mremap+0xfad/0x1f80 mm/mremap.c:1921
>  __do_sys_mremap+0x119/0x170 mm/mremap.c:1977
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f00d0b8ebe9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffe5ea5ee98 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
> RAX: ffffffffffffffda RBX: 00007f00d0db5fa0 RCX: 00007f00d0b8ebe9
> RDX: 0000000000400000 RSI: 0000000000c00000 RDI: 0000200000000000
> RBP: 00007ffe5ea5eef0 R08: 0000200000c00000 R09: 0000000000000000
> R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000002
> R13: 00007f00d0db5fa0 R14: 00007f00d0db5fa0 R15: 0000000000000005
>  </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@...glegroups.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 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