Message-ID: <4FDA5413.9080400@linux.intel.com>
Date: Thu, 14 Jun 2012 14:13:55 -0700
From: "H. Peter Anvin" <hpa@linux.intel.com>
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To: Rik van Riel <riel@redhat.com>
CC: Borislav Petkov <bp@amd64.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
        sjhill@mips.com, ralf@linux-mips.org,
        Rob Herring <rob.herring@calxeda.com>,
        Russell King <rmk+kernel@arm.linux.org.uk>,
        Nicolas Pitre <nico@linaro.org>
Subject: Re: bugs in page colouring code
References: <20120613152936.363396d5@cuia.bos.redhat.com> <20120614103627.GA25940@aftab.osrc.amd.com> <4FD9DFCE.1070609@redhat.com> <4FDA5087.7090606@linux.intel.com> <4FDA519F.4080204@redhat.com>
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On 06/14/2012 02:03 PM, Rik van Riel wrote:
> On 06/14/2012 04:58 PM, H. Peter Anvin wrote:
>> On 06/14/2012 05:57 AM, Rik van Riel wrote:
>>>
>>> However, I expect that on x86 many applications expect
>>> MAP_FIXED to just work, and enforcing that would be
>>> more trouble than it's worth.
>>>
>>
>> MAP_FIXED, is well, fixed.  It means that performance be screwed, if we
>> can fulfill the request we MUST do so.
> 
> My codebase now has a separate arch_align_addr function
> for x86, which is surprisingly similar to the generic
> one :)

I am much more skeptical to disabling page coloring in the !PF_RANDOMIZE
case when no address hint is proposed.  I would like to at least try
running without it, perhaps with a chicken bit in a sysctl.

	-hpa

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