Re: [PATCH v8 2/3] mm/hwpoison: put page in already hwpoisoned case with MF_COUNT_INCREASED

From: Mike Kravetz <mike.kravetz@oracle.com>
To: Naoya Horiguchi <naoya.horiguchi@linux.dev>, linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Miaohe Lin <linmiaohe@huawei.com>, Yang Shi <shy828301@gmail.com>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Naoya Horiguchi <naoya.horiguchi@nec.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 2/3] mm/hwpoison: put page in already hwpoisoned case with MF_COUNT_INCREASED
Date: Thu, 14 Apr 2022 12:41:20 -0700	[thread overview]
Message-ID: <e713ea07-0e9e-9033-347e-cbf6429cfef5@oracle.com> (raw)
In-Reply-To: <20220408135323.1559401-3-naoya.horiguchi@linux.dev>

On 4/8/22 06:53, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@nec.com>
> 
> In already hwpoisoned case, memory_failure() is supposed to return with
> releasing the page refcount taken for error handling. But currently the
> refcount is not released when called with MF_COUNT_INCREASED, which
> makes page refcount inconsistent.  This should be rare and non-critical,
> but it might be inconvenient in testing (unpoison doesn't work).
> 
> Suggested-by: Miaohe Lin <linmiaohe@huawei.com>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
> ---
>  mm/memory-failure.c | 2 ++
>  1 file changed, 2 insertions(+)

Thanks!

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>

-- 
Mike Kravetz

> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 2020944398c9..b2e32cdc3823 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1811,6 +1811,8 @@ int memory_failure(unsigned long pfn, int flags)
>  		res = -EHWPOISON;
>  		if (flags & MF_ACTION_REQUIRED)
>  			res = kill_accessing_process(current, pfn, flags);
> +		if (flags & MF_COUNT_INCREASED)
> +			put_page(p);
>  		goto unlock_mutex;
>  	}
>  