linux-kernel - Re: [PATCH] [31/31] HWPOISON: Add a madvise() injector for soft page offlining

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Date:	Sat, 19 Jun 2010 14:36:28 +0200
From:	Michael Kerrisk <mtk.manpages@...il.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	fengguang.wu@...el.com, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Michael Kerrisk <mtk.manpages@...il.com>
Subject: Re: [PATCH] [31/31] HWPOISON: Add a madvise() injector for soft page 
	offlining

Hi Andi,

On Tue, Dec 8, 2009 at 11:16 PM, Andi Kleen <andi@...stfloor.org> wrote:
>
> Process based injection is much easier to handle for test programs,
> who can first bring a page into a specific state and then test.
> So add a new MADV_SOFT_OFFLINE to soft offline a page, similar
> to the existing hard offline injector.

I see that this made its way into 2.6.33. Could you write a short
piece on it for the madvise.2 man page?

Thanks,

Michael


> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
>
> ---
>  include/asm-generic/mman-common.h |    1 +
>  mm/madvise.c                      |   15 ++++++++++++---
>  2 files changed, 13 insertions(+), 3 deletions(-)
>
> Index: linux/include/asm-generic/mman-common.h
> ===================================================================
> --- linux.orig/include/asm-generic/mman-common.h
> +++ linux/include/asm-generic/mman-common.h
> @@ -35,6 +35,7 @@
>  #define MADV_DONTFORK  10              /* don't inherit across fork */
>  #define MADV_DOFORK    11              /* do inherit across fork */
>  #define MADV_HWPOISON  100             /* poison a page for testing */
> +#define MADV_SOFT_OFFLINE 101          /* soft offline page for testing */
>
>  #define MADV_MERGEABLE   12            /* KSM may merge identical pages */
>  #define MADV_UNMERGEABLE 13            /* KSM may not merge identical pages */
> Index: linux/mm/madvise.c
> ===================================================================
> --- linux.orig/mm/madvise.c
> +++ linux/mm/madvise.c
> @@ -9,6 +9,7 @@
>  #include <linux/pagemap.h>
>  #include <linux/syscalls.h>
>  #include <linux/mempolicy.h>
> +#include <linux/page-isolation.h>
>  #include <linux/hugetlb.h>
>  #include <linux/sched.h>
>  #include <linux/ksm.h>
> @@ -222,7 +223,7 @@ static long madvise_remove(struct vm_are
>  /*
>  * Error injection support for memory error handling.
>  */
> -static int madvise_hwpoison(unsigned long start, unsigned long end)
> +static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end)
>  {
>        int ret = 0;
>
> @@ -233,6 +234,14 @@ static int madvise_hwpoison(unsigned lon
>                int ret = get_user_pages_fast(start, 1, 0, &p);
>                if (ret != 1)
>                        return ret;
> +               if (bhv == MADV_SOFT_OFFLINE) {
> +                       printk(KERN_INFO "Soft offlining page %lx at %lx\n",
> +                               page_to_pfn(p), start);
> +                       ret = soft_offline_page(p, MF_COUNT_INCREASED);
> +                       if (ret)
> +                               break;
> +                       continue;
> +               }
>                printk(KERN_INFO "Injecting memory failure for page %lx at %lx\n",
>                       page_to_pfn(p), start);
>                /* Ignore return value for now */
> @@ -333,8 +342,8 @@ SYSCALL_DEFINE3(madvise, unsigned long,
>        size_t len;
>
>  #ifdef CONFIG_MEMORY_FAILURE
> -       if (behavior == MADV_HWPOISON)
> -               return madvise_hwpoison(start, start+len_in);
> +       if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
> +               return madvise_hwpoison(behavior, start, start+len_in);
>  #endif
>        if (!madvise_behavior_valid(behavior))
>                return error;
>
> --
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> see: http://www.linux-mm.org/ .
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>



-- 
Michael Kerrisk Linux man-pages maintainer;
http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface", http://blog.man7.org/
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