[v6.1] kernel BUG in hpage_collapse_scan_file

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3594f306da12 Linux 6.1.147
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1734d4a2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2be97b627a5d7554
dashboard link: https://syzkaller.appspot.com/bug?extid=d3672301e4208b8ac935
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0d2a884e198e/disk-3594f306.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/23d3643328c7/vmlinux-3594f306.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ef83d78711e3/Image-3594f306.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d36723...@syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at mm/khugepaged.c:1785!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 5986 Comm: syz.1.703 Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : collapse_file mm/khugepaged.c:1785 [inline]
pc : hpage_collapse_scan_file+0x3200/0x422c mm/khugepaged.c:2248
lr : collapse_file mm/khugepaged.c:1785 [inline]
lr : hpage_collapse_scan_file+0x3200/0x422c mm/khugepaged.c:2248
sp : ffff8000210074a0
x29: ffff800021007700 x28: ffff0000c0922f98 x27: ffff8000210075e0
x26: ffff800021007600 x25: dfff800000000000 x24: 00000000000343e2
x23: ffff800021007560 x22: ffff0000d2b24438 x21: ffff0000f4492d00
x20: 0000000000000001 x19: 00000000000001e2 x18: ffff800011aabce0
x17: ffff8000181e7000 x16: ffff8000082d0ec4 x15: 0000000000000002
x14: 0000000000000003 x13: 0000000000ff0100 x12: 0000000000080000
x11: 0000000000001eeb x10: ffff80002229c000 x9 : ffff800008917b80
x8 : 0000000000001eec x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000010
x2 : 0000000000000008 x1 : 00000000000001e2 x0 : 0000000000000000
Call trace:
collapse_file mm/khugepaged.c:1785 [inline]
hpage_collapse_scan_file+0x3200/0x422c mm/khugepaged.c:2248
madvise_collapse+0x580/0xc10 mm/khugepaged.c:2703
madvise_vma_behavior mm/madvise.c:1085 [inline]
madvise_walk_vmas mm/madvise.c:1259 [inline]
do_madvise+0x8f8/0x2920 mm/madvise.c:1438
__do_sys_madvise mm/madvise.c:1451 [inline]
__se_sys_madvise mm/madvise.c:1449 [inline]
__arm64_sys_madvise+0xa4/0xc0 mm/madvise.c:1449
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: aa1a03e0 97fa5974 d4210000 97ee27f3 (d4210000)
---[ end trace 0000000000000000 ]---


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 3594f306da12 Linux 6.1.147
git tree: linux-6.1.y

console output: https://syzkaller.appspot.com/x/log.txt?x=108f9782580000

kernel config: https://syzkaller.appspot.com/x/.config?x=2be97b627a5d7554
dashboard link: https://syzkaller.appspot.com/bug?extid=d3672301e4208b8ac935
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14ebf034580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=136cd4a2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0d2a884e198e/disk-3594f306.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/23d3643328c7/vmlinux-3594f306.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ef83d78711e3/Image-3594f306.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d36723...@syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at mm/khugepaged.c:1785!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:

CPU: 1 PID: 4464 Comm: syz.0.16 Not tainted 6.1.147-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : collapse_file mm/khugepaged.c:1785 [inline]
pc : hpage_collapse_scan_file+0x3200/0x422c mm/khugepaged.c:2248
lr : collapse_file mm/khugepaged.c:1785 [inline]
lr : hpage_collapse_scan_file+0x3200/0x422c mm/khugepaged.c:2248

sp : ffff800020d774a0
x29: ffff800020d77700 x28: ffff0000c4bb1ca8 x27: ffff800020d775e0
x26: ffff800020d77600 x25: dfff800000000000 x24: 00000000000343e2
x23: ffff800020d77560 x22: ffff0000cf8b21b8 x21: ffff0000df672d00

x20: 0000000000000001 x19: 00000000000001e2 x18: ffff800011aabce0

x17: ffff8000181e7000 x16: ffff8000082d0ec4 x15: 0000000000000000
x14: 0000000000000003 x13: 0000000000ff0100 x12: 0000000000ff0100
x11: ff00800008917b80 x10: 0000000000000000 x9 : ffff800008917b80
x8 : ffff0000c3e78000 x7 : 0000000000000000 x6 : 0000000000000000

x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000010
x2 : 0000000000000008 x1 : 00000000000001e2 x0 : 0000000000000000
Call trace:
collapse_file mm/khugepaged.c:1785 [inline]
hpage_collapse_scan_file+0x3200/0x422c mm/khugepaged.c:2248
madvise_collapse+0x580/0xc10 mm/khugepaged.c:2703
madvise_vma_behavior mm/madvise.c:1085 [inline]
madvise_walk_vmas mm/madvise.c:1259 [inline]
do_madvise+0x8f8/0x2920 mm/madvise.c:1438
__do_sys_madvise mm/madvise.c:1451 [inline]
__se_sys_madvise mm/madvise.c:1449 [inline]
__arm64_sys_madvise+0xa4/0xc0 mm/madvise.c:1449
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: aa1a03e0 97fa5974 d4210000 97ee27f3 (d4210000)
---[ end trace 0000000000000000 ]---


---

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.

[syzbot]

syzbot suspects this issue was fixed by commit:

commit c5273a8111b27418a552c32b740b1f53681be65b
Author: Liu Shixin <liush...@huawei.com>
Date: Sat Jan 11 03:45:11 2025 +0000

mm: khugepaged: fix call hpage_collapse_scan_file() for anonymous vma

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1258fe62580000
start commit: 3594f306da12 Linux 6.1.147
git tree: linux-6.1.y

kernel config: https://syzkaller.appspot.com/x/.config?x=2be97b627a5d7554
dashboard link: https://syzkaller.appspot.com/bug?extid=d3672301e4208b8ac935

userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11bbf034580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=117cd4a2580000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: mm: khugepaged: fix call hpage_collapse_scan_file() for anonymous vma

For information about bisection process see: https://goo.gl/tpsmEJ#bisection