linux-kernel - Re: [PATCH] kmemcheck: don't track pages allocated with interrupts disabled

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Message-ID: <484AC165.7000702@firstfloor.org>
Date:	Sat, 07 Jun 2008 19:12:05 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Vegard Nossum <vegard.nossum@...il.com>
CC:	Pekka Enberg <penberg@...helsinki.fi>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kmemcheck: don't track pages allocated with interrupts
 disabled

Vegard Nossum wrote:
> It seems that I was wrong regarding the set_memory_4k() approach. It seems
> to only have worked because we were lucky. 

You just put it in the wrong place I think.

> We may later reinstate the code
> to disable PSE, but this time not unconditionally, perhaps with a config
> option or boot-time option.

It would be kind of guaranteed (not sure 100%) together with
CONFOG_DEBUG_PAGEALLOC and Thomas' page table pool (the pool is ifdefed
on that)

But a far better solution is to just split all the pages in  the system
with set_memory_4k() at boot time  (and memory hot add time) when you
know you're not in interrupt context.

I believe that would be the right solution for DEBUG_PAGEALLOC too.

-Andi

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