Date:   Tue, 31 Jan 2023 15:17:42 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Cc:     Matthias Brugger <matthias.bgg@gmail.com>,
        Alistair Popple <apopple@nvidia.com>,
        John Hubbard <jhubbard@nvidia.com>,
        <chinwen.chang@mediatek.com>, <andrew.yang@mediatek.com>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-mediatek@lists.infradead.org>
Subject: Re: [PATCH] mm/gup: Add folio to list when folio_isolate_lru()
 succeed
Message-Id: <20230131151742.df43c3fd11bda01b613234ef@linux-foundation.org>
In-Reply-To: <20230131063206.28820-1-Kuan-Ying.Lee@mediatek.com>
References: <20230131063206.28820-1-Kuan-Ying.Lee@mediatek.com>
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On Tue, 31 Jan 2023 14:32:06 +0800 Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com> wrote:

> If we call folio_isolate_lru() successfully, we will get
> return value 0. We need to add this folio to the
> movable_pages_list.
> 
> Fixes: 67e139b02d99 ("mm/gup.c: refactor check_and_migrate_movable_pages()")
> Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
>
> ...
>
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1914,7 +1914,7 @@ static unsigned long collect_longterm_unpinnable_pages(
>  			drain_allow = false;
>  		}
>  
> -		if (!folio_isolate_lru(folio))
> +		if (folio_isolate_lru(folio))
>  			continue;
>  
>  		list_add_tail(&folio->lru, movable_page_list);

Thanks.  What are the user-visible effects of this bug?