linux-kernel - Re: [PATCH v7u1 01/31] x86, mm: Fix page table early allocation offset checking

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Message-ID: <CAE9FiQXpAJgS_ADW-c23QsqywsX=vL_PSg=crYgLgep5nzVpxg@mail.gmail.com>
Date:	Fri, 4 Jan 2013 13:50:18 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Borislav Petkov <bp@...en8.de>, Yinghai Lu <yinghai@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jan Kiszka <jan.kiszka@....de>,
	Jason Wessel <jason.wessel@...driver.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7u1 01/31] x86, mm: Fix page table early allocation
 offset checking

On Thu, Jan 3, 2013 at 11:17 PM, Borislav Petkov <bp@...en8.de> wrote:
> On Thu, Jan 03, 2013 at 04:48:21PM -0800, Yinghai Lu wrote:
>> During debugging loading kernel above 4G, found one page if is not used
>> in BRK with early page allocation.
>>
>> pgt_buf_top is address that can not be used, so should check if that new
>> end is above that top, otherwise last page will not be used.
>>
>> Fix that checking and also add print out for every allocation from BRK.
>
> This commit message still bothers the hell out of me. Please, fix it up
> to something more readable like the below, for example:
>
> "pgt_buf_top is an address which cannot be used so we should check
> whether the new 'end' is above it. Otherwise, the last BRK page remains
> unused.
>
> Fix that check and add a debug printout of every BRK allocation."

but your changelog is wrong.

it is NOT last BRK page.

it is NOT every BRK allocation.
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