linux-kernel - Re: [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear

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Date:	Tue, 8 May 2007 10:13:52 -0700
From:	"Satyam Sharma" <satyam.sharma@...il.com>
To:	"Pekka Enberg" <penberg@...helsinki.fi>
Cc:	"Michael Tokarev" <mjt@....msk.ru>,
	"Shani Moideen" <shani.moideen@...ro.com>, ebiederm@...ssion.com,
	linux-kernel@...r.kernel.org, kernel-janitors@...ts.osdl.org
Subject: Re: [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in kernel/kexec.c

On 5/8/07, Pekka Enberg <penberg@...helsinki.fi> wrote:
> Shani Moideen wrote:
> > >                 ptr = kmap(page);
> > > -               memset(ptr, 0, PAGE_SIZE);
> > > +               clear_page(ptr);
>
> On 5/8/07, Michael Tokarev <mjt@....msk.ru> wrote:
> > I wonder if it's worth to invent kzmap() or something like that... ;)
>
> I am counting 59 kmap + memset pairs in the kernel, so perhaps it is
> worth it to reduce kernel text size.

Stuff of the sort already exists. Look for clear_highpage(),
clear_user_highpage() and memclear_highpage_flush (recently renamed to
zero_user_page, see -mm). But they all use kmap_atomic() -- kmap()
variants would have to be added. Also, they're all inlines, so I'm not
sure you'd be able to cut down text size, but still getting rid of
open-coding is always good.
-
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