linux-kernel - Re: [PATCH 3/4] memory-hotplug: clear hwpoisoned flag when onlining pages

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Message-ID: <50644639.9000804@gmail.com>
Date:	Thu, 27 Sep 2012 20:27:37 +0800
From:	Ni zhan Chen <nizhan.chen@...il.com>
To:	wency@...fujitsu.com
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	rientjes@...gle.com, liuj97@...il.com, len.brown@...el.com,
	benh@...nel.crashing.org, paulus@...ba.org, minchan.kim@...il.com,
	akpm@...ux-foundation.org, kosaki.motohiro@...fujitsu.com,
	isimatu.yasuaki@...fujitsu.com
Subject: Re: [PATCH 3/4] memory-hotplug: clear hwpoisoned flag when onlining
 pages

On 09/27/2012 01:45 PM, wency@...fujitsu.com wrote:
> From: Wen Congyang <wency@...fujitsu.com>
>
> hwpoisoned may set when we offline a page by the sysfs interface
> /sys/devices/system/memory/soft_offline_page or
> /sys/devices/system/memory/hard_offline_page. If we don't clear
> this flag when onlining pages, this page can't be freed, and will
> not in free list. So we can't offline these pages again. So we
> should clear this flag when onlining pages.

page hwpoisoned maybe cause by a multi-bit ECC memory or cache failure, 
so this page should not be used, why you online and free it again? can 
any users use it?

>
> CC: David Rientjes <rientjes@...gle.com>
> CC: Jiang Liu <liuj97@...il.com>
> CC: Len Brown <len.brown@...el.com>
> CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> CC: Paul Mackerras <paulus@...ba.org>
> Cc: Minchan Kim <minchan.kim@...il.com>
> CC: Andrew Morton <akpm@...ux-foundation.org>
> CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> CC: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> Signed-off-by: Wen Congyang <wency@...fujitsu.com>
> ---
>   mm/memory_hotplug.c |    8 ++++++++
>   1 files changed, 8 insertions(+), 0 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 6a5b90d..9a5b10f 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -431,6 +431,14 @@ EXPORT_SYMBOL_GPL(__online_page_increment_counters);
>   
>   void __online_page_free(struct page *page)
>   {
> +#ifdef CONFIG_MEMORY_FAILURE
> +	/* The page may be marked HWPoisoned by soft/hard offline page */
> +	if (PageHWPoison(page)) {
> +		atomic_long_sub(1, &mce_bad_pages);
> +		ClearPageHWPoison(page);
> +	}
> +#endif
> +
>   	ClearPageReserved(page);
>   	init_page_count(page);
>   	__free_page(page);

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