linux-kernel - Re: [PATCH v2 2/2] hugetlb: Provide safer dummy values for HPAGE_MASK and HPAGE

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Date:	Fri, 18 Nov 2011 09:14:17 -0800
From:	David Daney <ddaney.cavm@...il.com>
To:	Sergei Shtylyov <sshtylyov@...sta.com>,
	Andrew Morton <akpm@...ux-foundation.org>
CC:	linux-mips@...ux-mips.org, ralf@...ux-mips.org,
	linux-kernel@...r.kernel.org, David Daney <david.daney@...ium.com>
Subject: Re: [PATCH v2 2/2] hugetlb: Provide safer dummy values for HPAGE_MASK
 and HPAGE_SIZE

On 11/18/2011 12:56 AM, Sergei Shtylyov wrote:
> Hello.
>
> On 18-11-2011 1:57, David Daney wrote:
>
>> From: David Daney<david.daney@...ium.com>
>
>> It was pointed out by David Rientjes that the dummy values for
>> HPAGE_MASK and HPAGE_SIZE are quite unsafe. It they are inadvertently
>> used with !CONFIG_HUGETLB_PAGE, compilation would succeed, but the
>> resulting code would surly not do anything sensible.
>>
>> Place BUG() in the these dummy definitions, as we do in similar
>> circumstances in other places, so any abuse can be easily detected.
>>
>> Since the only sane place to use these symbols when
>> !CONFIG_HUGETLB_PAGE is on dead code paths, the BUG() cause any actual
>> code to be emitted by the compiler.
>
> You mean "doesn't cause"?

Yes.

I mentioned this in a different message to akpm, but I am not sure if I 
should resend the patch with a corrected change log.

David Daney

>
>> Cc: David Rientjes<rientjes@...gle.com>
>> Signed-off-by: David Daney<david.daney@...ium.com>
>
> WBR, Sergei
>
>

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