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SubjectRe: [PATCH 10/10] mm/migrate.c: call detach_page_private to cleanup code
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On 5/23/20 1:53 AM, Andrew Morton wrote:
> On Fri, 22 May 2020 09:18:25 +0200 Guoqing Jiang <guoqing.jiang@cloud.ionos.com> 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.

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