linux-kernel - Re: [PATCH mm-new v2 1/1] mm/khugepaged: abort collapse scan on non-swap entries

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f07edfc2-0952-486f-ae47-5e3bbd77e4c0@redhat.com>
Date: Wed, 1 Oct 2025 10:31:07 +0200
From: David Hildenbrand <david@...hat.com>
To: Lance Yang <lance.yang@...ux.dev>, akpm@...ux-foundation.org
Cc: lorenzo.stoakes@...cle.com, Liam.Howlett@...cle.com, baohua@...nel.org,
 baolin.wang@...ux.alibaba.com, dev.jain@....com, hughd@...gle.com,
 ioworker0@...il.com, kirill@...temov.name, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, mpenttil@...hat.com, npache@...hat.com,
 ryan.roberts@....com, ziy@...dia.com, richard.weiyang@...il.com
Subject: Re: [PATCH mm-new v2 1/1] mm/khugepaged: abort collapse scan on
 non-swap entries

On 01.10.25 05:22, Lance Yang wrote:
> From: Lance Yang <lance.yang@...ux.dev>
> 
> Currently, special non-swap entries (like migration, hwpoison, or PTE
> markers) are not caught early in hpage_collapse_scan_pmd(), leading to
> failures deep in the swap-in logic.
> 
> hpage_collapse_scan_pmd()
>   `- collapse_huge_page()
>       `- __collapse_huge_page_swapin() -> fails!
> 
> As David suggested[1], this patch skips any such non-swap entries
> early. If any one is found, the scan is aborted immediately with the
> SCAN_PTE_NON_PRESENT result, as Lorenzo suggested[2], avoiding wasted
> work.
> 
> [1] https://lore.kernel.org/linux-mm/7840f68e-7580-42cb-a7c8-1ba64fd6df69@redhat.com
> [2] https://lore.kernel.org/linux-mm/7df49fe7-c6b7-426a-8680-dcd55219c8bd@lucifer.local
> 
> Suggested-by: David Hildenbrand <david@...hat.com>
> Suggested-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> Signed-off-by: Lance Yang <lance.yang@...ux.dev>
> ---

Could have mentioned you adjust the flow of code to resemble what we 
have in __collapse_huge_page_isolate().

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers

David / dhildenb