linux-kernel - Re: [PATCH] build fix for generic debug pagealloc

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Message-Id: <200904032238.55438.rjw@sisk.pl>
Date:	Fri, 3 Apr 2009 22:38:53 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Akinobu Mita <akinobu.mita@...il.com>,
	Alexander Beregalov <a.beregalov@...il.com>,
	"linux-next@...r.kernel.org" <linux-next@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, linux-arch@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] build fix for generic debug pagealloc

On Friday 03 April 2009, Ingo Molnar wrote:
> 
> * Andrew Morton <akpm@...ux-foundation.org> wrote:
> 
> > > +config DEBUG_PAGEALLOC
> > > +	bool "Debug page memory allocations"
> > > +	depends on DEBUG_KERNEL && ARCH_SUPPORTS_DEBUG_PAGEALLOC
> > > +	depends on !HIBERNATION || !PPC && !SPARC
> > > +	---help---
> > > +	  Unmap pages from the kernel linear mapping after free_pages().
> > > +	  This results in a large slowdown, but helps to find certain types
> > > +	  of memory corruptions.
> > > +
> > 
> > I guess this is why it wasn't discovered in my compile testing.  
> > It's quite regrettable that `make allmodconfig' didn't enable the 
> > feature. That's what allmodconfig is for.
> 
> Hm, i _do_ remember some hibernation magic fix from Rafael, in the 
> area of debugalloc. Many months ago.
> 
> Rafael, is it supposed to work? If yes, i think we should unblock 
> it.

Yes, it is, at least on x86.

ISTR using DEBUG_PAGEALLOC with hibernation quite some time ago already.

Thanks,
Rafael
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