From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] build fix for generic debug pagealloc
Date: Wed, 8 Apr 2009 15:05:10 +0200
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References: <a4423d670904020421k7395e11dwe70d4223cb817e0a@mail.gmail.com> <20090402094522.b29004c8.akpm@linux-foundation.org> <20090403164450.GC3047@elte.hu> <200904032238.55438.rjw@sisk.pl>
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To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Andrew Morton <akpm@linux-foundation.org>, Akinobu Mita <akinobu.mita@gmail.com>, Alexander Beregalov <a.beregalov@gmail.com>, "linux-next@vger.kernel.org" <linux-next@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, linux-arch@vger.kernel.org, "David S. Miller" <davem@davemloft.net>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>


* Rafael J. Wysocki <rjw@sisk.pl> wrote:

> On Friday 03 April 2009, Ingo Molnar wrote:
> > 
> > * Andrew Morton <akpm@linux-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.

Could you please send a patch to Andrew then to remove the above 
dependency?

	Ingo