Re: [PATCH v2 1/2] mm: Uncharge poisoned pages

From: Balbir Singh <bsingharora@gmail.com>
To: Michal Hocko <mhocko@kernel.org>,
	Andi Kleen <andi@firstfloor.org>,
	Johannes Weiner <hannes@cmpxchg.org>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	akpm@linux-foundation.org,
	Vladimir Davydov <vdavydov.dev@gmail.com>
Subject: Re: [PATCH v2 1/2] mm: Uncharge poisoned pages
Date: Thu, 04 May 2017 11:21:09 +1000	[thread overview]
Message-ID: <1493860869.8082.1.camel@gmail.com> (raw)
In-Reply-To: <20170502185507.GB19165@dhcp22.suse.cz>

> @@ -5527,7 +5527,7 @@ static void uncharge_list(struct list_head *page_list)
>  		next = page->lru.next;
>  
>  		VM_BUG_ON_PAGE(PageLRU(page), page);
> -		VM_BUG_ON_PAGE(page_count(page), page);
> +		VM_BUG_ON_PAGE(!PageHWPoison(page) && page_count(page), page);
>  
>  		if (!page->mem_cgroup)
>  			continue;
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 8a6bd3a9eb1e..4497d9619bb4 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -541,6 +541,13 @@ static int delete_from_lru_cache(struct page *p)
>  		 */
>  		ClearPageActive(p);
>  		ClearPageUnevictable(p);
> +
> +		/*
> +		 * Poisoned page might never drop its ref count to 0 so we have to
> +		 * uncharge it manually from its memcg.
> +		 */
> +		mem_cgroup_uncharge(p);
> +

Yep, that is the right fix

https://lkml.org/lkml/2017/4/26/133

Reviewed-by: Balbir Singh <bsingharora@gmail.com>

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