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

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Message-ID: <SA1PR11MB713082CA93E9B1C5F22CFBBE891BA@SA1PR11MB7130.namprd11.prod.outlook.com>
Date: Mon, 29 Sep 2025 16:30:16 +0000
From: "Zhuo, Qiuxu" <qiuxu.zhuo@...el.com>
To: "Luck, Tony" <tony.luck@...el.com>, Jiaqi Yan <jiaqiyan@...gle.com>
CC: "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"david@...hat.com" <david@...hat.com>, "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

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 😊).

> and avoid a crash in that case too?
> 
> -Tony
> 
> [1] terrible name, pick something better.