linux-kernel - Re: [PATCH v2 2/2] mm: skip HWPoisoned pages when onlining pages

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Date:   Wed, 26 Apr 2017 12:10:15 +1000
From:   Balbir Singh <bsingharora@...il.com>
To:     Laurent Dufour <ldufour@...ux.vnet.ibm.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org
Subject: Re: [PATCH v2 2/2] mm: skip HWPoisoned pages when onlining pages

On Tue, 2017-04-25 at 16:27 +0200, Laurent Dufour wrote:
> The commit b023f46813cd ("memory-hotplug: skip HWPoisoned page when
> offlining pages") skip the HWPoisoned pages when offlining pages, but
> this should be skipped when onlining the pages too.
> 
> Signed-off-by: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
> ---
>  mm/memory_hotplug.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 6fa7208bcd56..741ddb50e7d2 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -942,6 +942,10 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
>  	if (PageReserved(pfn_to_page(start_pfn)))
>  		for (i = 0; i < nr_pages; i++) {
>  			page = pfn_to_page(start_pfn + i);
> +			if (PageHWPoison(page)) {
> +				ClearPageReserved(page);

Why do we clear page reserved? Also if the page is marked PageHWPoison, it
was never offlined to begin with? Or do you expect this to be set on newly
hotplugged memory? Also don't we need to skip the entire pageblock?

Balbir Singh.