linux-kernel - Re: [PATCH 1/3] resources: introduce generic page_is

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Message-Id: <20100122131017.544dd91b.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Fri, 22 Jan 2010 13:10:17 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Wu Fengguang <fengguang.wu@...el.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Chen Liqin <liqin.chen@...plusct.com>,
	Lennox Wu <lennox.wu@...il.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Américo Wang <xiyou.wangcong@...il.com>,
	linux-mips@...ux-mips.org, Yinghai Lu <yinghai@...nel.org>,
	x86@...nel.org, LKML <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>, shaohui.zheng@...el.com
Subject: Re: [PATCH 1/3] resources: introduce generic page_is_ram()

On Fri, 22 Jan 2010 11:21:03 +0800
Wu Fengguang <fengguang.wu@...el.com> wrote:

> It's based on walk_system_ram_range(), for archs that don't have
> their own page_is_ram().
> 
> The static verions in MIPS and SCORE are also made global.
> 
> CC: Chen Liqin <liqin.chen@...plusct.com>
> CC: Lennox Wu <lennox.wu@...il.com>
> CC: Ralf Baechle <ralf@...ux-mips.org>
> CC: Am辿rico Wang <xiyou.wangcong@...il.com>
> CC: linux-mips@...ux-mips.org
> CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> 
> CC: Yinghai Lu <yinghai@...nel.org>
> Signed-off-by: Wu Fengguang <fengguang.wu@...el.com>

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

Maybe adding comment like this is good for reviewers..

"This page_is_ram() returns true if specified address is registered
 as System RAM in io_resource list."

AFAIK, this "System RAM" information has been used for kdump to grab valid
memory area and seems good for the kernel itself.

Thanks,
-Kame

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> ---
>  arch/mips/mm/init.c    |    2 +-
>  arch/score/mm/init.c   |    2 +-
>  include/linux/ioport.h |    2 ++
>  kernel/resource.c      |   11 +++++++++++
>  4 files changed, 15 insertions(+), 2 deletions(-)
> 
> --- linux-mm.orig/kernel/resource.c	2010-01-22 11:20:34.000000000 +0800
> +++ linux-mm/kernel/resource.c	2010-01-22 11:20:35.000000000 +0800
> @@ -327,6 +327,17 @@ int walk_system_ram_range(unsigned long 
>  
>  #endif
>  
> +#define PAGE_IS_RAM	24
> +static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
> +{
> +	return PAGE_IS_RAM;
> +}
> +int __attribute__((weak)) page_is_ram(unsigned long pfn)
> +{
> +	return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram);
> +}
> +#undef PAGE_IS_RAM
> +
>  /*
>   * Find empty slot in the resource tree given range and alignment.
>   */
> --- linux-mm.orig/include/linux/ioport.h	2010-01-22 11:20:34.000000000 +0800
> +++ linux-mm/include/linux/ioport.h	2010-01-22 11:20:35.000000000 +0800
> @@ -191,5 +191,7 @@ extern int
>  walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
>  		void *arg, int (*func)(unsigned long, unsigned long, void *));
>  
> +extern int page_is_ram(unsigned long pfn);
> +
>  #endif /* __ASSEMBLY__ */
>  #endif	/* _LINUX_IOPORT_H */
> --- linux-mm.orig/arch/score/mm/init.c	2010-01-22 11:20:34.000000000 +0800
> +++ linux-mm/arch/score/mm/init.c	2010-01-22 11:20:35.000000000 +0800
> @@ -59,7 +59,7 @@ static unsigned long setup_zero_page(voi
>  }
>  
>  #ifndef CONFIG_NEED_MULTIPLE_NODES
> -static int __init page_is_ram(unsigned long pagenr)
> +int page_is_ram(unsigned long pagenr)
>  {
>  	if (pagenr >= min_low_pfn && pagenr < max_low_pfn)
>  		return 1;
> --- linux-mm.orig/arch/mips/mm/init.c	2010-01-22 11:20:34.000000000 +0800
> +++ linux-mm/arch/mips/mm/init.c	2010-01-22 11:20:35.000000000 +0800
> @@ -298,7 +298,7 @@ void __init fixrange_init(unsigned long 
>  }
>  
>  #ifndef CONFIG_NEED_MULTIPLE_NODES
> -static int __init page_is_ram(unsigned long pagenr)
> +int page_is_ram(unsigned long pagenr)
>  {
>  	int i;
>  
> 
> 
> 

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