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([2001:16b8:48bc:3c00:e80e:f5df:f780:7d57]) by smtp.gmail.com with ESMTPSA id u17sm13588498ejg.1.2020.05.24.12.02.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 24 May 2020 12:02:11 -0700 (PDT) Subject: Re: [PATCH 10/10] mm/migrate.c: call detach_page_private to cleanup code To: Andrew Morton Cc: Dave Chinner , viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org, willy@infradead.org References: <20200517214718.468-1-guoqing.jiang@cloud.ionos.com> <20200517214718.468-11-guoqing.jiang@cloud.ionos.com> <20200521225220.GV2005@dread.disaster.area> <906f7469-492d-febc-c7ed-b01830ae900d@cloud.ionos.com> <20200522165301.727977de1d39ac5bfb683ed0@linux-foundation.org> From: Guoqing Jiang Message-ID: <54e99e19-0e84-c85b-b3f5-aa2c14ec6d65@cloud.ionos.com> Date: Sun, 24 May 2020 21:02:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200522165301.727977de1d39ac5bfb683ed0@linux-foundation.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/23/20 1:53 AM, Andrew Morton wrote: > On Fri, 22 May 2020 09:18:25 +0200 Guoqing Jiang wrote: > >>>> - ClearPagePrivate(page); >>>> - set_page_private(newpage, page_private(page)); >>>> - set_page_private(page, 0); >>>> - put_page(page); >>>> + set_page_private(newpage, detach_page_private(page)); >>> attach_page_private(newpage, detach_page_private(page)); >> Mattew had suggested it as follows, but not sure if we can reorder of >> the setup of >> the bh and setting PagePrivate, so I didn't want to break the original >> syntax. >> >> @@ -797,11 +797,7 @@ static int __buffer_migrate_page(struct address_space *mapping, >> if (rc != MIGRATEPAGE_SUCCESS) >> goto unlock_buffers; >> >> - ClearPagePrivate(page); >> - set_page_private(newpage, page_private(page)); >> - set_page_private(page, 0); >> - put_page(page); >> - get_page(newpage); >> + attach_page_private(newpage, detach_page_private(page)); >> >> bh = head; >> do { >> @@ -810,8 +806,6 @@ static int __buffer_migrate_page(struct address_space *mapping, >> >> } while (bh != head); >> >> - SetPagePrivate(newpage); >> - >> if (mode != MIGRATE_SYNC_NO_COPY) > This is OK - coherency between PG_private and the page's buffer > ring is maintained by holding lock_page(). Appreciate for your explanation. Thanks, Guoqing > I have (effectively) applied the above change.