linux-kernel - Re: [PATCH v1] mm, hwpoison: add is_free_buddy

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Date:   Fri, 10 Sep 2021 13:16:37 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Naoya Horiguchi <naoya.horiguchi@...ux.dev>, linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Tony Luck <tony.luck@...el.com>,
        Oscar Salvador <osalvador@...e.de>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Michal Hocko <mhocko@...e.com>, Yang Shi <shy828301@...il.com>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] mm, hwpoison: add is_free_buddy_page() in
 HWPoisonHandlable()

On 09.09.21 02:41, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@....com>
> 
> commit fcc00621d88b ("mm/hwpoison: retry with shake_page() for
> unhandlable pages") changes the return value of __get_hwpoison_page() to
> retry for transiently unhandlable cases.  However, __get_hwpoison_page()
> currently fails to properly judge buddy pages as handlable, so hard/soft
> offline for buddy pages always fail as "unhandlable page".  This is
> totally regrettable.
> 
> So let's add is_free_buddy_page() in HWPoisonHandlable(), so that
> __get_hwpoison_page() returns different return values between buddy
> pages and unhandlable pages as intended.
> 
> Fixes: fcc00621d88b ("mm/hwpoison: retry with shake_page() for unhandlable pages")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>
> ---
>   mm/memory-failure.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git v5.14-rc7-mmotm-2021-08-23-16-42/mm/memory-failure.c v5.14-rc7-mmotm-2021-08-23-16-42_patched/mm/memory-failure.c
> index 60df8fcd0444..3416c55be810 100644
> --- v5.14-rc7-mmotm-2021-08-23-16-42/mm/memory-failure.c
> +++ v5.14-rc7-mmotm-2021-08-23-16-42_patched/mm/memory-failure.c
> @@ -1126,7 +1126,7 @@ static int page_action(struct page_state *ps, struct page *p,
>    */
>   static inline bool HWPoisonHandlable(struct page *page)
>   {
> -	return PageLRU(page) || __PageMovable(page);
> +	return PageLRU(page) || __PageMovable(page) || is_free_buddy_page(page);
>   }
>   
>   static int __get_hwpoison_page(struct page *page)
> 

LGTM and I agree that code might desrve some cleanups.

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Thanks,

David / dhildenb