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Date: Thu, 15 Nov 2018 13:23:02 +0100
From: Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH RFC 6/6] PM / Hibernate: exclude all PageOffline() pages
Message-ID: <20181115122302.GR23831@dhcp22.suse.cz>
References: <20181114211704.6381-1-david@redhat.com>
 <20181114211704.6381-7-david@redhat.com>
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Sender: owner-linux-mm@kvack.org
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To: David Hildenbrand <david@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, devel@linuxdriverproject.org, linux-fsdevel@vger.kernel.org, linux-pm@vger.kernel.org, xen-devel@lists.xenproject.org, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Pavel Machek <pavel@ucw.cz>, Len Brown <len.brown@intel.com>, Andrew Morton <akpm@linux-foundation.org>, Matthew Wilcox <willy@infradead.org>, "Michael S. Tsirkin" <mst@redhat.com>

On Wed 14-11-18 22:17:04, David Hildenbrand wrote:
[...]
> diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> index b0308a2c6000..01db1d13481a 100644
> --- a/kernel/power/snapshot.c
> +++ b/kernel/power/snapshot.c
> @@ -1222,7 +1222,7 @@ static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn)
>  	BUG_ON(!PageHighMem(page));
>  
>  	if (swsusp_page_is_forbidden(page) ||  swsusp_page_is_free(page) ||
> -	    PageReserved(page))
> +	    PageReserved(page) || PageOffline(page))
>  		return NULL;
>  
>  	if (page_is_guard(page))
> @@ -1286,6 +1286,9 @@ static struct page *saveable_page(struct zone *zone, unsigned long pfn)
>  	if (swsusp_page_is_forbidden(page) || swsusp_page_is_free(page))
>  		return NULL;
>  
> +	if (PageOffline(page))
> +		return NULL;
> +
>  	if (PageReserved(page)
>  	    && (!kernel_page_present(page) || pfn_is_nosave(pfn)))
>  		return NULL;

Btw. now that you are touching this file could you also make
s@pfn_to_page@pfn_to_online_page@ please? We really do not want to touch
offline pfn ranges in general. A separate patch for that of course.

Thanks!
-- 
Michal Hocko
SUSE Labs