linux-kernel - Re: [PATCH 12/15] kmemleak: Enable the building of the memory leak detector

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Date:	Fri, 12 Dec 2008 17:27:06 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	Dave Hansen <dave@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/15] kmemleak: Enable the building of the memory leak
	detector

On Wed, 2008-12-10 at 11:20 -0800, Dave Hansen wrote:
> On Wed, 2008-12-10 at 18:28 +0000, Catalin Marinas wrote:
> > +config DEBUG_MEMLEAK
> > +       bool "Kernel memory leak detector"
> > +       default n
> > +       depends on EXPERIMENTAL
> > +       select DEBUG_SLAB if SLAB
> > +       select SLUB_DEBUG if SLUB
> > +       select DEBUG_FS
> > +       select STACKTRACE
> > +       select FRAME_POINTER
> > +       select KALLSYMS
> 
> So, not all architectures have STACKTRACE or FRAME_POINTER.  I think a
> few of these should at least be done with depends.

I think it could depend on STACKTRACE_SUPPORT. Alternatively, it could
select STACKTRACE only if it is supported, though for architectures
without it, the kmemleak reports wouldn't be very useful.

Does FRAME_POINTER even matter? I think STACKTRACE should be enough to
get the backtrace. I even have some ARM patches for stack unwinding
where FRAME_POINTER is disabled (and shouldn't be enabled).

> Is this feature accessible if DEBUG_FS=n?  It seems to compile OK, but I
> wonder if it is useful.

Well, it is recommended. If you don't have this, you can't trigger a
scan manually by reading the /sys/kernel/debug/memleak file (have to
rely on the automatic thread). In my local tree (not published yet), I
also added support for run-time configuration by writing to this file.
Is there any disadvantage in always selecting DEBUG_FS?

Thanks.

-- 
Catalin

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