Message-ID: <4fc2c008-2384-4d94-b1bf-f0a076585a4a@redhat.com>
Date: Thu, 5 Jun 2025 08:11:02 +0200
From: David Hildenbrand <david@...hat.com>
To: syzbot <syzbot+3b220254df55d8ca8a61@...kaller.appspotmail.com>,
 Liam.Howlett@...cle.com, akpm@...ux-foundation.org, harry.yoo@...cle.com,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 lorenzo.stoakes@...cle.com, riel@...riel.com,
 syzkaller-bugs@...glegroups.com, vbabka@...e.cz, Jens Axboe
 <axboe@...nel.dk>, Catalin Marinas <catalin.marinas@....com>
Subject: Re: [syzbot] [mm?] kernel BUG in try_to_unmap_one (2)

On 05.06.25 07:38, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    d7fa1af5b33e Merge branch 'for-next/core' into for-kernelci

Hmmm, another very odd page-table mapping related problem on that tree 
found on arm64 only:

https://lore.kernel.org/all/f031d35b-13e3-4dec-a89c-f221331be735@kernel.dk/T/#mef6b1f00bd47724e3ba756d9c898128ab010ed34


Are we maybe corrupting ptes/pfns etc?

> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=1757300c580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=89c13de706fbf07a
> dashboard link: https://syzkaller.appspot.com/bug?extid=3b220254df55d8ca8a61
> compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
> userspace arch: arm64
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=150f7ed4580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13745970580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/da97ad659b2c/disk-d7fa1af5.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/659e123552a8/vmlinux-d7fa1af5.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/6ec5dbf4643e/Image-d7fa1af5.gz.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+3b220254df55d8ca8a61@...kaller.appspotmail.com
> 
> head: 05ffc00000000309 fffffdffc6628001 0080000000000000 0000000100000000
> head: ffffffff00000000 0000000000000024 00000000ffffffff 0000000000000200
> page dumped because: VM_BUG_ON_FOLIO(!pvmw.pte)
> ------------[ cut here ]------------
> kernel BUG at mm/rmap.c:1955!
> Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
> Modules linked in:
> CPU: 1 UID: 0 PID: 9503 Comm: syz-executor315 Not tainted 6.15.0-rc7-syzkaller-gd7fa1af5b33e #0 PREEMPT
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
> pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : try_to_unmap_one+0x2c54/0x2d40 mm/rmap.c:1955
> lr : try_to_unmap_one+0x2c54/0x2d40 mm/rmap.c:1955
> sp : ffff80009e906380
> x29: ffff80009e9065e0 x28: 0000000000000038
>   x27: ffff0000c9dbee80
> x26: fffffdffc6628018 x25: fffffdffc6628030 x24: dfff800000000000
> x23: ffff0000d84efdc0 x22: ffff0000d84efde0 x21: 0000000000000001
> x20: fffffdffc6628000 x19: 05ffc00000020849 x18: 00000000ffffffff
> x17: 0000000000000000 x16: ffff80008adbe9e4 x15: 0000000000000001
> x14: 1fffe0003386f2e2 x13: 0000000000000000 x12: 0000000000000000
> x11: ffff60003386f2e3 x10: 0000000000ff0100 x9 : 664e624a89365e00
> x8 : 664e624a89365e00 x7 : 0000000000000001 x6 : 0000000000000001
> x5 : ffff80009e905a98 x4 : ffff80008f415ba0 x3 : ffff8000807b4b68
> x2 : 0000000000000001 x1 : 0000000100000001 x0 : 000000000000002f
> Call trace:
>   try_to_unmap_one+0x2c54/0x2d40 mm/rmap.c:1955 (P)
>   rmap_walk_anon+0x47c/0x640 mm/rmap.c:2834
>   rmap_walk+0x128/0x1e8 mm/rmap.c:2939
>   try_to_unmap+0xc4/0x120 mm/rmap.c:2263
>   unmap_poisoned_folio+0x278/0x4a4 mm/memory-failure.c:1610
>   shrink_folio_list+0x608/0x4410 mm/vmscan.c:1131
>   reclaim_folio_list+0xdc/0x5d0 mm/vmscan.c:2217
>   reclaim_pages+0x420/0x544 mm/vmscan.c:2254
>   madvise_cold_or_pageout_pte_range+0x1d38/0x20d4 mm/madvise.c:434
>   walk_pmd_range mm/pagewalk.c:130 [inline]
>   walk_pud_range mm/pagewalk.c:226 [inline]
>   walk_p4d_range mm/pagewalk.c:264 [inline]
>   walk_pgd_range+0xb4c/0x16bc mm/pagewalk.c:305
>   __walk_page_range+0x13c/0x654 mm/pagewalk.c:412
>   walk_page_range_mm+0x4fc/0x7dc mm/pagewalk.c:505
>   walk_page_range+0x80/0x98 mm/pagewalk.c:584
>   madvise_pageout_page_range mm/madvise.c:617 [inline]
>   madvise_pageout mm/madvise.c:644 [inline]
>   madvise_vma_behavior mm/madvise.c:1269 [inline]
>   madvise_walk_vmas mm/madvise.c:1530 [inline]
>   madvise_do_behavior+0x1940/0x2908 mm/madvise.c:1695
>   do_madvise mm/madvise.c:1782 [inline]
>   __do_sys_madvise mm/madvise.c:1790 [inline]
>   __se_sys_madvise mm/madvise.c:1788 [inline]
>   __arm64_sys_madvise+0x10c/0x154 mm/madvise.c:1788
>   __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>   invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
>   el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
>   do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
>   el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767
>   el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
>   el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
> Code: f9404be0 b0051fc1 910c8021 97fdefe4 (d4210000)
> ---[ end trace 0000000000000000 ]---
> 
> 
> ---
> 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
> 


-- 
Cheers,

David / dhildenb

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