linux-kernel - Re: [PATCH 05/10] mm, util: Use dup

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Message-Id: <20120925142948.6b062cb6.akpm@linux-foundation.org>
Date:	Tue, 25 Sep 2012 14:29:48 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Ezequiel Garcia <elezegarcia@...il.com>
Cc:	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	Pekka Enberg <penberg@...nel.org>
Subject: Re: [PATCH 05/10] mm, util: Use dup_user to duplicate user memory

On Sat,  8 Sep 2012 17:47:54 -0300
Ezequiel Garcia <elezegarcia@...il.com> wrote:

> Previously the strndup_user allocation was being done through memdup_user,
> and the caller was wrongly traced as being strndup_user
> (the correct trace must report the caller of strndup_user).
> 
> This is a common problem: in order to get accurate callsite tracing,
> a utils function can't allocate through another utils function,
> but instead do the allocation himself (or inlined).
> 
> Here we fix this by creating an always inlined dup_user() function to
> performed the real allocation and to be used by memdup_user and strndup_user.

This patch increases util.o's text size by 238 bytes.  A larger kernel
with a worsened cache footprint.

And we did this to get marginally improved tracing output?  This sounds
like a bad tradeoff to me.

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