linux-kernel - Re: [PATCH v2 2/5] kmemleak: add clear command support

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Date:	Fri, 4 Sep 2009 13:26:53 -0700
From:	"Luis R. Rodriguez" <lrodriguez@...eros.com>
To:	Catalin Marinas <catalin.marinas@....com>
CC:	Luis Rodriguez <Luis.Rodriguez@...eros.com>,
	"torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"penberg@...helsinki.fi" <penberg@...helsinki.fi>,
	"mcgrof@...il.com" <mcgrof@...il.com>
Subject: Re: [PATCH v2 2/5] kmemleak: add clear command support

On Thu, Sep 03, 2009 at 09:52:11AM -0700, Catalin Marinas wrote:
> On Thu, 2009-09-03 at 01:35 -0400, Luis R. Rodriguez wrote:
> > In an ideal world your kmemleak output will be small,
> > when its not you can use the clear command to ingore previously
> > annotated kmemleak objects. We do this by painting them black.
> 
> Making the objects "black" means that they are completely ignored by
> kmemleak and they are assumed not to contain any valid references.
> Therefore they won't be scanned and many of the newly allocated objects
> would be false positives.

Got it, BTW can you elaborate as to why painting objects black would
create false positives for newly allocated objects? I fail to understand
why.

> You may want to make them "gray" and only those which were reported as
> unreferenced, something like below:
> 
>         if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
>                 make_gray_object(object->pointer)

Thanks, will use this.

  Luis
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