Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] mm: migrate: add missing flush_dcache_page for non-mapped
 page migrate
To:     Vlastimil Babka <vbabka@suse.cz>, Lars Persson <larper@axis.com>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
CC:     <linux-mips@vger.kernel.org>
References: <20190219123212.29838-1-larper@axis.com>
 <65ed6463-b61f-81ff-4fcc-27f4071a28da@suse.cz>
 <ed4dd065-5e1b-dc20-2778-6d0a727914a8@axis.com>
 <2de280a9-e82a-876c-e13b-a2e48d89700a@suse.cz>
From:   Lars Persson <lars.persson@axis.com>
Message-ID: <24af691e-03ab-d79a-ddbd-7057dcf46826@axis.com>
Date:   Tue, 26 Feb 2019 12:57:37 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.5.1
MIME-Version: 1.0
In-Reply-To: <2de280a9-e82a-876c-e13b-a2e48d89700a@suse.cz>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 2/26/19 11:07 AM, Vlastimil Babka wrote:
> On 2/26/19 9:40 AM, Lars Persson wrote:
>>> What about CC stable and a Fixes tag, would it be applicable here?
>>>
>>
>> Yes this is candidate for stable so let's add:
>> Cc: <stable@vger.kernel.org>
>>
>> I do not find a good candidate for a Fixes tag.
> 
> How bout a version range where the bug needs to be fixed then?
> 

The distinction between mapped and non-mapped old page was introduced in 2ebba6b7e1d9 ("mm: unmapped page migration avoid unmap+remap overhead") so at least it applies to stable 4.4+.

Before that patch there was always a call to remove_migration_ptes() but I cannot conclude if those earlier versions actually will reach the flush_dcache_page call if the old page was unmapped.