linux-kernel - Re: [PATCH 6/6] mm: Postpone the disabling of kmemleak early logging

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Message-ID: <53696B65.6070807@oracle.com>
Date:	Tue, 06 May 2014 19:08:21 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Catalin Marinas <catalin.marinas@....com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Li Zefan <lizefan@...wei.com>
Subject: Re: [PATCH 6/6] mm: Postpone the disabling of kmemleak early logging

On 05/06/2014 05:52 PM, Catalin Marinas wrote:
> On 6 May 2014, at 19:15, Sasha Levin <sasha.levin@...cle.com> wrote:
>> On 05/06/2014 01:05 PM, Catalin Marinas wrote:
>>> On Tue, May 06, 2014 at 04:20:27PM +0100, Sasha Levin wrote:
>>>> On 05/02/2014 09:41 AM, Catalin Marinas wrote:
>>>>> Currently, kmemleak_early_log is disabled at the beginning of the
>>>>> kmemleak_init() function, before the full kmemleak tracing is actually
>>>>> enabled. In this small window, kmem_cache_create() is called by kmemleak
>>>>> which triggers additional memory allocation that are not traced. This
>>>>> patch moves the kmemleak_early_log disabling further down and at the
>>>>> same time with full kmemleak enabling.
>>>>>
>>>>> Signed-off-by: Catalin Marinas <catalin.marinas@....com>
>>>>> Cc: Andrew Morton <akpm@...ux-foundation.org>
>>>>
>>>> This patch makes the kernel die during the boot process:
>>>>
>>>> [   24.471801] BUG: unable to handle kernel paging request at ffffffff922f2b93
>>>> [   24.472496] IP: [<ffffffff922f2b93>] log_early+0x0/0xcd
>>>
>>> Thanks for reporting this. I assume you run with
>>> CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF enabled and kmemleak_early_log remains
>>> set even though kmemleak is not in use.
>>>
>>> Does the patch below fix it?
>>
>> Nope, that didn't help as I don't have DEBUG_KMEMLEAK_DEFAULT_OFF enabled.
>>
>> For reference:
>>
>> $ cat .config | grep KMEMLEAK
>> CONFIG_HAVE_DEBUG_KMEMLEAK=y
>> CONFIG_DEBUG_KMEMLEAK=y
>> CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE=400
>> # CONFIG_DEBUG_KMEMLEAK_TEST is not set
>> # CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF is not set
> 
> I assume your dmesg shows some kmemleak error during boot? I’ll send
> another patch tomorrow.

Besides the BUG, I have these kmemleak messages:

$ grep kmemleak out.txt
[    0.000000] kmemleak: Kernel memory leak detector disabled
[    0.000000] kmemleak: Early log buffer exceeded (2742), please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE

Thanks,
Sasha

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