linux-kernel - Re: [RFC PATCH 08/12] mm: use mirrorable to switch allocate mirrored memory

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Date:	Tue, 09 Jun 2015 16:06:00 +0900
From:	Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Xishi Qiu <qiuxishi@...wei.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	nao.horiguchi@...il.com, Yinghai Lu <yinghai@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>, mingo@...e.hu,
	Xiexiuqi <xiexiuqi@...wei.com>,
	Hanjun Guo <guohanjun@...wei.com>,
	"Luck, Tony" <tony.luck@...el.com>
CC:	Linux MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 08/12] mm: use mirrorable to switch allocate mirrored
 memory

On 2015/06/04 22:02, Xishi Qiu wrote:
> Add a new interface in path /proc/sys/vm/mirrorable. When set to 1, it means
> we should allocate mirrored memory for both user and kernel processes.
>
> Signed-off-by: Xishi Qiu <qiuxishi@...wei.com>

I can't see why do we need this switch. If this is set, all GFP_HIGHUSER will use
mirrored memory ?

Or will you add special MMAP/madvise flag to use mirrored memory ?

Thanks,
-Kame

> ---
>   include/linux/mmzone.h | 1 +
>   kernel/sysctl.c        | 9 +++++++++
>   mm/page_alloc.c        | 1 +
>   3 files changed, 11 insertions(+)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index f82e3ae..20888dd 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -85,6 +85,7 @@ struct mirror_info {
>   };
>
>   extern struct mirror_info mirror_info;
> +extern int sysctl_mirrorable;
>   #  define is_migrate_mirror(migratetype) unlikely((migratetype) == MIGRATE_MIRROR)
>   #else
>   #  define is_migrate_mirror(migratetype) false
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 2082b1a..dc2625e 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1514,6 +1514,15 @@ static struct ctl_table vm_table[] = {
>   		.extra2		= &one,
>   	},
>   #endif
> +#ifdef CONFIG_MEMORY_MIRROR
> +	{
> +		.procname	= "mirrorable",
> +		.data		= &sysctl_mirrorable,
> +		.maxlen		= sizeof(sysctl_mirrorable),
> +		.mode		= 0644,
> +		.proc_handler	= proc_dointvec_minmax,
> +	},
> +#endif
>   	{
>   		.procname	= "user_reserve_kbytes",
>   		.data		= &sysctl_user_reserve_kbytes,
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 249a8f6..63b90ca 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -212,6 +212,7 @@ int user_min_free_kbytes = -1;
>
>   #ifdef CONFIG_MEMORY_MIRROR
>   struct mirror_info mirror_info;
> +int sysctl_mirrorable = 0;
>   #endif
>
>   static unsigned long __meminitdata nr_kernel_pages;
>


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