linux-kernel - Re: [PATCH 5/5] mm: poison page struct

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Message-ID: <alpine.DEB.2.11.1410080208410.9795@gentwo.org>
Date:	Wed, 8 Oct 2014 02:10:13 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Dave Hansen <dave.hansen@...el.com>
cc:	Sasha Levin <sasha.levin@...cle.com>, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, hughd@...gle.com,
	mgorman@...e.de
Subject: Re: [PATCH 5/5] mm: poison page struct

On Tue, 7 Oct 2014, Dave Hansen wrote:

> Does this break slub's __cmpxchg_double_slab trick?  I thought it
> required page->freelist and page->counters to be doubleword-aligned.

Sure that would be required for it to work.

> It's not like we really require this optimization when we're debugging,
> but trying to use it will unnecessarily slow things down.

Debugging by inserting more data into the page struct will already cause a
significant slow down because the cache footprint of key functions will
increase significantly. I would think that using the fallback functions
is reasonable in this scenario,
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