linux-kernel - Re: [PATCH 2/2] kmemleak: Ignore the aperture memory hole on x86

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Message-Id: <1251556208.5518.5.camel@pc1117.cambridge.arm.com>
Date:	Sat, 29 Aug 2009 15:30:08 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] kmemleak: Ignore the aperture memory hole on x86_64

On Sat, 2009-08-29 at 15:31 +0200, Ingo Molnar wrote:
> * Catalin Marinas <catalin.marinas@....com> wrote:
> > --- a/arch/x86/kernel/aperture_64.c
> > +++ b/arch/x86/kernel/aperture_64.c
> > @@ -20,6 +20,7 @@
> >  #include <linux/bitops.h>
> >  #include <linux/ioport.h>
> >  #include <linux/suspend.h>
> > +#include <linux/kmemleak.h>
> >  #include <asm/e820.h>
> >  #include <asm/io.h>
> >  #include <asm/iommu.h>
> > @@ -94,6 +95,11 @@ static u32 __init allocate_aperture(void)
> >  	 * code for safe
> >  	 */
> >  	p = __alloc_bootmem_nopanic(aper_size, aper_size, 512ULL<<20);
> > +	/*
> > +	 * Kmemleak should not scan this block as it may not be mapped via the
> > +	 * kernel direct mapping.
> > +	 */
> > +	kmemleak_ignore(p);
> >  	if (!p || __pa(p)+aper_size > 0xffffffff) {
> >  		printk(KERN_ERR
> >  			"Cannot allocate aperture memory hole (%p,%uK)\n",
> 
> This sure does not look right for the rare but theoretically 
> possible !p case, does it?

All the kmemleak_* callbacks check for (p && !IS_ERR(p)), just to
simplify the calling site.

-- 
Catalin

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