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

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Date:	Mon, 31 Aug 2009 10:38:13 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] kmemleak: Ignore the aperture memory hole on x86_64


* Catalin Marinas <catalin.marinas@....com> wrote:

> 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.

Indeed, i see. It's OK this way then.

	Ingo
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