linux-kernel - Re: [RFC v2] arm:extend the reserved mrmory for initrd to be page aligned

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Message-ID: <20141205184418.GF31222@e104818-lin.cambridge.arm.com>
Date:	Fri, 5 Dec 2014 18:44:18 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Will Deacon <Will.Deacon@....com>,
	"Wang, Yalin" <Yalin.Wang@...ymobile.com>,
	"'linux-mm@...ck.org'" <linux-mm@...ck.org>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
	"'linux-arm-kernel@...ts.infradead.org'" 
	<linux-arm-kernel@...ts.infradead.org>,
	"'linux-arm-msm@...r.kernel.org'" <linux-arm-msm@...r.kernel.org>,
	Peter Maydell <Peter.Maydell@....com>
Subject: Re: [RFC v2] arm:extend the reserved mrmory for initrd to be page
 aligned

On Fri, Dec 05, 2014 at 05:27:02PM +0000, Russell King - ARM Linux wrote:
> On Fri, Dec 05, 2014 at 05:07:45PM +0000, Catalin Marinas wrote:
> > From 8e317c6be00abe280de4dcdd598d2e92009174b6 Mon Sep 17 00:00:00 2001
> > From: Catalin Marinas <catalin.marinas@....com>
> > Date: Fri, 5 Dec 2014 16:41:52 +0000
> > Subject: [PATCH] Revert "ARM: 8167/1: extend the reserved memory for initrd to
> >  be page aligned"
> > 
> > This reverts commit 421520ba98290a73b35b7644e877a48f18e06004. There is
> > no guarantee that the boot-loader places other images like dtb in a
> > different page than initrd start/end. When this happens, such pages must
> > not be freed. The free_reserved_area() already takes care of rounding up
> > "start" and rounding down "end" to avoid freeing partially used pages.
> > 
> > In addition to the revert, this patch also removes the arm32
> > PAGE_ALIGN(end) when calculating the size of the memory to be poisoned.
> 
> which makes the summary line rather misleading, and I really don't think
> we need to do this on ARM for the simple reason that we've been doing it
> for soo long that it can't be an issue.

I started this as a revert and then realised that it doesn't solve
anything for arm32 without changing the poisoning.

Anyway, if you are happy with how it is, I'll drop the arm32 part. As I
said yesterday, the issue is worse for arm64 with 64K pages.

-- 
Catalin
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