linux-kernel - Re: [2.6.35-rc6 patch] increase kmemleak robustness at boot

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Message-ID: <AANLkTi=+_bSNY3pnowGmU-NEVzL7VWYeGhT44y7SL3L7@mail.gmail.com>
Date:	Thu, 29 Jul 2010 21:39:31 +0100
From:	Catalin Marinas <catalin.marinas@...il.com>
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	Daniel J Blueman <daniel.blueman@...il.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [2.6.35-rc6 patch] increase kmemleak robustness at boot

On 29 July 2010 19:50, Pekka Enberg <penberg@...helsinki.fi> wrote:
> On Thu, Jul 29, 2010 at 9:03 PM, Daniel J Blueman
> <daniel.blueman@...il.com> wrote:
>>> If it's just kmemleak_init() we're talking about, slab caches are up at that
>>> point so you can just use kmalloc().
>>
>> The slab allocator isn't up at this point. With
>> CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE set to 16K elements, an extra 3MB
>> of __initdata memory is used, but freed afterwards, and it works
>> great.
>
> Right. I guess the required earlylog buffer size would be smaller if
> we initialized kmemleak earlier. Can we do that in mm_init() after
> kmem_cache_init()?

Kmemleak uses kmem_cache_alloc() internally so we could initialise it
as soon as kmem_cache_init() was called. But it's really strange the
amount of early allocations that Daniel is getting. I've been happy so
far with 400, usually with standard Ubuntu-like configs and some
debugging turned on. Any idea what's causing these allocations?

-- 
Catalin
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