linux-kernel - Re: [PATCH 1/1] mm: prevent poison consumption when splitting THP

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: <c1294b63-eeee-4d99-82b6-93eb3a6d0af9@redhat.com>
Date: Mon, 29 Sep 2025 19:25:16 +0200
From: David Hildenbrand <david@...hat.com>
To: "Zhuo, Qiuxu" <qiuxu.zhuo@...el.com>, "Luck, Tony" <tony.luck@...el.com>,
 Jiaqi Yan <jiaqiyan@...gle.com>
Cc: "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
 "lorenzo.stoakes@...cle.com" <lorenzo.stoakes@...cle.com>,
 "linmiaohe@...wei.com" <linmiaohe@...wei.com>,
 "ziy@...dia.com" <ziy@...dia.com>,
 "baolin.wang@...ux.alibaba.com" <baolin.wang@...ux.alibaba.com>,
 "Liam.Howlett@...cle.com" <Liam.Howlett@...cle.com>,
 "npache@...hat.com" <npache@...hat.com>,
 "ryan.roberts@....com" <ryan.roberts@....com>,
 "dev.jain@....com" <dev.jain@....com>, "baohua@...nel.org"
 <baohua@...nel.org>, "nao.horiguchi@...il.com" <nao.horiguchi@...il.com>,
 "Chen, Farrah" <farrah.chen@...el.com>,
 "linux-mm@...ck.org" <linux-mm@...ck.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 Andrew Zaborowski <andrew.zaborowski@...el.com>
Subject: Re: [PATCH 1/1] mm: prevent poison consumption when splitting THP

On 29.09.25 18:30, Zhuo, Qiuxu wrote:
> Hi Tony,
> 
>> From: Luck, Tony <tony.luck@...el.com>
>> [...]
>> Subject: RE: [PATCH 1/1] mm: prevent poison consumption when splitting THP
>>
>>> Miaohe mentioned in another e-mail that there was an HWPoisoned flag
>> for the raw error 4K page.
>>> We could use that flag just to skip that raw error page and still use
>>> the zeropage for other healthy sub-pages. I'll try that.
>>
>> That HWPoisoned flag is only set for raw pages where an error has been
>> detected. Maybe Linux could implement an
>> "is_this_page_all_zero_mc_safe()"[1] that would catch undetected poison
> 
> This sounds like a great suggestion to me.
> Let's see what others think about this and the name (though the name already LGTM 😊).

The function name is just ... special. Not the good type of special IMHO. :)

Note that we'll be moving to pages_identical() in [1]. Maybe we would 
want a pages_identical_mc() or sth. like that as a follow up later.


So in any case, make that a follow-up work on top of a simple fix.

[1] https://lore.kernel.org/all/20250922021458.68123-1-lance.yang@linux.dev/

-- 
Cheers

David / dhildenb