linux-kernel - Re: [BUG] Page allocation failures with newest kernels

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Date:	Tue, 31 May 2016 14:15:20 +0100
From:	Will Deacon <will.deacon@....com>
To:	Yehuda Yitschak <yehuday@...vell.com>
Cc:	Marcin Wojtas <mw@...ihalf.com>,
	Robin Murphy <robin.murphy@....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>,
	Lior Amsalem <alior@...vell.com>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Arnd Bergmann <arnd@...db.de>,
	Grzegorz Jaszczyk <jaz@...ihalf.com>,
	Nadav Haklai <nadavh@...vell.com>,
	Tomasz Nowicki <tn@...ihalf.com>,
	Gregory Clément 
	<gregory.clement@...e-electrons.com>
Subject: Re: [BUG] Page allocation failures with newest kernels

On Tue, May 31, 2016 at 01:10:44PM +0000, Yehuda Yitschak wrote:
> During some of the stress tests we also came across a different warning
> from the arm64  page management code
> It looks like a race is detected between HW and SW marking a bit in the PTE

A72 (which I believe is the CPU in that SoC) is a v8.0 CPU and therefore
doesn't have hardware DBM.

> Not sure it's really related but I thought it might give a clue on the issue
> http://pastebin.com/ASv19vZP

There have been a few patches from Catalin to fix up the hardware DBM
patches, so it might be worth trying to reproduce this failure with a
more recent kernel. I doubt this is related to the allocation failures,
however.

Will