linux-kernel - Re: [PATCH v2 1/3] kmemleak: allow freeing internal objects after kmemleak was disabled

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Message-Id: <F7314A69-24BE-42B9-8E99-8F9292B397C4@arm.com>
Date:	Fri, 21 Mar 2014 23:37:03 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	Li Zefan <lizefan@...wei.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH v2 1/3] kmemleak: allow freeing internal objects after kmemleak was disabled

Hi Li,

On 17 Mar 2014, at 04:07, Li Zefan <lizefan@...wei.com> wrote:
> Currently if kmemleak is disabled, the kmemleak objects can never be freed,
> no matter if it's disabled by a user or due to fatal errors.
> 
> Those objects can be a big waste of memory.
> 
>  OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME
> 1200264 1197433  99%    0.30K  46164       26    369312K kmemleak_object
> 
> With this patch, internal objects will be freed immediately if kmemleak is
> disabled explicitly by a user. If it's disabled due to a kmemleak error,
> The user will be informed, and then he/she can reclaim memory with:
> 
> 	# echo off > /sys/kernel/debug/kmemleak
> 
> v2: use "off" handler instead of "clear" handler to do this, suggested
>    by Catalin.

I think there was a slight misunderstanding. My point was about "echo
scan=off” before “echo off”, they can just be squashed into the
same action of the latter.

I would keep the “clear” part separately as per your first patch. I
recall people asked in the past to still be able to analyse the reports
even though kmemleak failed or was disabled.

Thanks,

Catalin--
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