linux-kernel - Re: [PATCH] mm/kmemleak: add support for re-enable kmemleak at runtime

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Message-Id: <CE7DF1D3-12AE-4A97-BF05-84FF223C8520@arm.com>
Date:	Sat, 18 Jan 2014 10:45:38 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	Jianguo Wu <wujianguo@...wei.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"rob@...dley.net" <rob@...dley.net>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Li Zefan <lizefan@...wei.com>, Wang Nan <wangnan0@...wei.com>
Subject: Re: [PATCH] mm/kmemleak: add support for re-enable kmemleak at runtime

On 18 Jan 2014, at 08:41, Jianguo Wu <wujianguo@...wei.com> wrote:
> On 2014/1/17 20:04, Catalin Marinas wrote:
>> On Fri, Jan 17, 2014 at 09:40:02AM +0000, Jianguo Wu wrote:
>>> Now disabling kmemleak is an irreversible operation, but sometimes
>>> we may need to re-enable kmemleak at runtime. So add a knob to enable
>>> kmemleak at runtime:
>>> echo on > /sys/kernel/debug/kmemleak
>> 
>> It is irreversible for very good reason: once it missed the initial
>> memory allocations, there is no way for kmemleak to build the object
>> reference graph and you'll get lots of false positives, pretty much
>> making it unusable.
> 
> Do you mean we didn't trace memory allocations during kmemleak disable period,
> and these memory may reference to new allocated objects after re-enable? 

Yes. Those newly allocated objects would be reported as leaks.

Catalin--
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