linux-kernel - Re: [PATCH V2] MCE: fix an error of mce_bad

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Message-ID: <20121211024522.GA10505@localhost>
Date:	Tue, 11 Dec 2012 10:45:22 +0800
From:	Fengguang Wu <fengguang.wu@...el.com>
To:	Xishi Qiu <qiuxishi@...wei.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Simon Jeons <simon.jeons@...il.com>,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	WuJianguo <wujianguo@...wei.com>,
	Liujiang <jiang.liu@...wei.com>, Vyacheslav.Dubeyko@...wei.com,
	Borislav Petkov <bp@...en8.de>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, wency@...fujitsu.com,
	Hanjun Guo <guohanjun@...wei.com>
Subject: Re: [PATCH V2] MCE: fix an error of mce_bad_pages statistics

On Tue, Dec 11, 2012 at 10:25:00AM +0800, Xishi Qiu wrote:
> On 2012/12/10 23:38, Andi Kleen wrote:
> 
> >> It is another topic, I mean since the page is poisoned, so why not isolate it
> >> from page buddy alocator in soft_offline_page() rather than in check_new_page().
> >> I find soft_offline_page() only migrate the page and mark HWPoison, the poisoned
> >> page is still managed by page buddy alocator.
> > 
> > Doing it in check_new_page is the only way if the page is currently
> > allocated by someone. Since that's not uncommon it's simplest to always
> > do it this way.
> > 
> > -Andi
> > 
> 
> Hi Andi,
> 
> The poisoned page is isolated in check_new_page, however the whole buddy block will
> be dropped, it seems to be a waste of memory.
> 
> Can we separate the poisoned page from the buddy block, then *only* drop the poisoned
> page?

That sounds like overkill. There are not so many free pages in a
typical server system.

Thanks,
Fengguang
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