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Date: Sat, 22 Oct 2011 16:27:18 +0200
Subject: Re: [PATCH 0/3] ARM 4Kstacks: introduction
From: "Andi Kleen" <andi@firstfloor.org>
To: =?iso-8859-1?Q?=22M=E5ns_Rullg=E5rd=22?= <mans@mansr.com>
Cc: "Ming Lei" <tom.leiming@gmail.com>, "Arnd Bergmann" <arnd@arndb.de>,
        linux-arm-kernel@lists.infradead.org,
        "Tim Bird" <tim.bird@am.sony.com>, "Joe Perches" <joe@perches.com>,
        "linux kernel" <linux-kernel@vger.kernel.org>,
        "Andi Kleen" <andi@firstfloor.org>,
        "Russell King" <rmk@arm.linux.org.uk>,
        "Thomas Gleixner" <tglx@linutronix.de>
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>> If system run for some time, sometimes it may be difficult for
>> memory allocator to allocate 2 continuous page frames even  there are
>> many spare page frames in system because of
>> fragment issue, so the patch does make sense. Anyway,
>> it provides one option for user to apply 4k stack to avoid
>> such kind of process creation failure.
>
> Can't page migration be used in these situations?

The kernel already uses it of course, assuming the pages are movable.
So if you are really worried about this, just define a movable zone.

-Andi