Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 10 Jul 2023 16:56:07 +0900
From:   Naoya Horiguchi <naoya.horiguchi@linux.dev>
To:     Miaohe Lin <linmiaohe@huawei.com>
Cc:     akpm@linux-foundation.org, naoya.horiguchi@nec.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/8] mm: memory-failure: fix potential permanently locked
 hpage
Message-ID: <20230710075607.GA1686200@ik1-406-35019.vs.sakura.ne.jp>
References: <20230708085744.3599311-1-linmiaohe@huawei.com>
 <20230708085744.3599311-2-linmiaohe@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20230708085744.3599311-2-linmiaohe@huawei.com>
Precedence: bulk

On Sat, Jul 08, 2023 at 04:57:37PM +0800, Miaohe Lin wrote:
> If hpage isn't Hugetlb page, MF_DELAYED is returned without unlock hpage
> leading to hpage permanently locked. But this shouldn't trigger in the
> real world because this PageHuge() check is just for potential problems.

Right, so this if-block is dead code, how about simply removing it?

Thanks,
Naoya Horiguchi

> 
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
>  mm/memory-failure.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index a6221a4bc5ea..d21ee27ad412 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1187,8 +1187,10 @@ static int me_huge_page(struct page_state *ps, struct page *p)
>  	struct address_space *mapping;
>  	bool extra_pins = false;
>  
> -	if (!PageHuge(hpage))
> +	if (!PageHuge(hpage)) {
> +		unlock_page(hpage);
>  		return MF_DELAYED;
> +	}
>  
>  	mapping = page_mapping(hpage);
>  	if (mapping) {
> -- 
> 2.33.0
> 
> 
>