linux-kernel - Re: Noticed Issue in kmemleak test module if inserted twice

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Message-ID: <AANLkTiltMUX2EzJrdsUhBFjPz0LTCYstunpRrzRBee8F@mail.gmail.com>
Date:	Wed, 16 Jun 2010 11:17:37 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Amit Agarwal <amit.agarr@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Noticed Issue in kmemleak test module if inserted twice

On 16 June 2010 09:52, Amit Agarwal <amit.agarr@...il.com> wrote:
> I backported the latest kmemleak(2.6.34-rc1) patches to my 2.6.29-RT kernel
> for ARM target.
> I am facing the issue while inserting the kmemleak-test.ko module twice in
> my 29-RT kernel.
> Step I followed.
> {{{
> # mount -t debugfs nodev /sys/kernel/debug/ # cat /sys/kernel/debug/kmemleak
> # echo scan > /sys/kernel/debug/kmemleak # cat /sys/kernel/debug/kmemleak
>  # insmod kmemleak-test.ko
>  # rmmod kmemleak-test.ko
> # insmod kmemleak-test.ko
> # cat /sys/kernel/debug/kmemleak
> cat: can't open '/sys/kernel/debug/kmemleak': Device or resource busy
> }}}
> I have attached the detail log with the mail.
> I am not clear is this the behaviour of kmemleak

It works fine on the latest kernel, so it's not a kmemleak bug. Most
likely it's a back-porting issue. From the log, kmemleak disabled
itself because of errors (freeing some blocks of memory by a pointer
to somewhere inside the block rather than to the beginning).

All I can say is make sure that the kmemleak_*() callbacks are
correct. The log gives you the backtrace of where kmemleak_free() was
called from, so that should help.

-- 
Catalin
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