linux-kernel - Re: [PATCH 1/4] mm: migrate: use a folio in add_page_for

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Message-ID: <001ee9b0-ea25-a896-e3ae-9a9b05a46546@huawei.com>
Date:   Thu, 3 Aug 2023 15:13:21 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Matthew Wilcox <willy@...radead.org>
CC:     Andrew Morton <akpm@...ux-foundation.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, Huang Ying <ying.huang@...el.com>,
        David Hildenbrand <david@...hat.com>
Subject: Re: [PATCH 1/4] mm: migrate: use a folio in add_page_for_migration()



On 2023/8/2 20:21, Matthew Wilcox wrote:
> On Wed, Aug 02, 2023 at 05:53:43PM +0800, Kefeng Wang wrote:
>>   	err = -EACCES;
>> -	if (page_mapcount(page) > 1 && !migrate_all)
>> -		goto out_putpage;
>> +	if (folio_estimated_sharers(folio) > 1 && !migrate_all)
>> +		goto out_putfolio;
> 
> I do not think this is the correct change.  Maybe leave this line
> alone.

Ok, I am aware of the discussion about this in other mail, will not
change it(also the next two patch about this function), or wait the
new work of David.
> 
>> -	if (PageHuge(page)) {
>> -		if (PageHead(page)) {
>> -			isolated = isolate_hugetlb(page_folio(page), pagelist);
>> +	if (folio_test_hugetlb(folio)) {
>> +		if (folio_test_large(folio)) {
> 
> This makes no sense when you read it.  All hugetlb folios are large,
> by definition.  Think about what this code used to do, and what it
> should be changed to.

hugetlb folio is self large folio, will drop redundant check