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

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Message-ID: <AANLkTin-lj5ZgtcvJhWcNiMuWSCQ39N8mqe_2fm8DDVR@mail.gmail.com>
Date:	Sat, 19 Jun 2010 15:25:16 +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
Subject: Re: [PATCH] [31/31] HWPOISON: Add a madvise() injector for soft page 
	offlining

Hi Andi,

Thanks for this. Some comments below.

On Sat, Jun 19, 2010 at 3:20 PM, Andi Kleen <andi@...stfloor.org> wrote:
> On Sat, Jun 19, 2010 at 02:36:28PM +0200, Michael Kerrisk wrote:
>> 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?
>
> Also fixed the previous snippet slightly.

(thanks)

> commit edb43354f0ffc04bf4f23f01261f9ea9f43e0d3d
> Author: Andi Kleen <ak@...ux.intel.com>
> Date:   Sat Jun 19 15:19:28 2010 +0200
>
>    MADV_SOFT_OFFLINE
>
>    Signed-off-by: Andi Kleen <ak@...ux.intel.com>
>
> diff --git a/man2/madvise.2 b/man2/madvise.2
> index db29feb..9dccd97 100644
> --- a/man2/madvise.2
> +++ b/man2/madvise.2
> @@ -154,7 +154,15 @@ processes.
>  This operation may result in the calling process receiving a
>  .B SIGBUS
>  and the page being unmapped.
> -This feature is intended for memory testing.
> +This feature is intended for testing of memory error handling code.
> +This feature is only available if the kernel was configured with
> +.BR CONFIG_MEMORY_FAILURE .
> +.TP
> +.BR MADV_SOFT_OFFLINE " (Since Linux 2.6.33)
> +Soft offline a page. This will result in the memory of the page
> +being copied to a new page and original page be offlined. The operation

Can you explain the term "offlined" please.

> +should be transparent to the calling process.

Does "should be transparent" mean "is normally invisible"?

Thanks,

Michael

> +This feature is intended for testing of memory error handling code.
>  This feature is only available if the kernel was configured with
>  .BR CONFIG_MEMORY_FAILURE .
>  .TP
>
>



-- 
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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