linux-kernel - Re: [PATCH v2 4/8] mm: migrate: use a folio in migrate_misplaced

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Message-ID: <875y4y65b8.fsf@yhuang6-desk2.ccr.corp.intel.com>
Date:   Tue, 29 Aug 2023 08:49:31 +0800
From:   "Huang, Ying" <ying.huang@...el.com>
To:     Zi Yan <ziy@...dia.com>
Cc:     Kefeng Wang <wangkefeng.wang@...wei.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        <willy@...radead.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <david@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>, <hughd@...gle.com>
Subject: Re: [PATCH v2 4/8] mm: migrate: use a folio in
 migrate_misplaced_page()

Zi Yan <ziy@...dia.com> writes:

> On 21 Aug 2023, at 7:56, Kefeng Wang wrote:
>
>> Use a folio in migrate_misplaced_page() to save compound_head() calls.
>>
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
>> ---
>>  mm/migrate.c | 23 ++++++++++++-----------
>>  1 file changed, 12 insertions(+), 11 deletions(-)
>
> LGTM. And a comment below. Reveiwed-by: Zi Yan <ziy@...dia.com>
>
>>
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 281eafdf8e63..fc728f9a383f 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -2521,17 +2521,18 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
>>  			   int node)
>>  {
>>  	pg_data_t *pgdat = NODE_DATA(node);
>> +	struct folio *folio = page_folio(page);
>>  	int isolated;
>>  	int nr_remaining;
>>  	unsigned int nr_succeeded;
>>  	LIST_HEAD(migratepages);
>> -	int nr_pages = thp_nr_pages(page);
>> +	int nr_pages = folio_nr_pages(folio);
>>
>>  	/*
>>  	 * Don't migrate file pages that are mapped in multiple processes
>>  	 * with execute permissions as they are probably shared libraries.
>>  	 */
>> -	if (page_mapcount(page) != 1 && page_is_file_lru(page) &&
>> +	if (page_mapcount(page) != 1 && folio_is_file_lru(folio) &&
>
> page_mapcount() is not converted, since folio_mapcount() is not equivalent
> to page_mapcount(). It can be converted and this function can be converted
> to migrate_misplaced_folio() once we have something like folio_num_sharers().

It seems that we can use folio_estimated_sharers() here.

--
Best Regards,
Huang, Ying

>>  	    (vma->vm_flags & VM_EXEC))
>>  		goto out;
>>
>> @@ -2539,29 +2540,29 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
>>  	 * Also do not migrate dirty pages as not all filesystems can move
>>  	 * dirty pages in MIGRATE_ASYNC mode which is a waste of cycles.
>>  	 */
>> -	if (page_is_file_lru(page) && PageDirty(page))
>> +	if (folio_is_file_lru(folio) && folio_test_dirty(folio))
>>  		goto out;
>>
>> -	isolated = numamigrate_isolate_folio(pgdat, page_folio(page));
>> +	isolated = numamigrate_isolate_folio(pgdat, folio);
>>  	if (!isolated)
>>  		goto out;
>>
>> -	list_add(&page->lru, &migratepages);
>> +	list_add(&folio->lru, &migratepages);
>>  	nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_folio,
>>  				     NULL, node, MIGRATE_ASYNC,
>>  				     MR_NUMA_MISPLACED, &nr_succeeded);
>>  	if (nr_remaining) {
>>  		if (!list_empty(&migratepages)) {
>> -			list_del(&page->lru);
>> -			mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
>> -					page_is_file_lru(page), -nr_pages);
>> -			putback_lru_page(page);
>> +			list_del(&folio->lru);
>> +			node_stat_mod_folio(folio, NR_ISOLATED_ANON +
>> +					folio_is_file_lru(folio), -nr_pages);
>> +			folio_putback_lru(folio);
>>  		}
>>  		isolated = 0;
>>  	}
>>  	if (nr_succeeded) {
>>  		count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
>> -		if (!node_is_toptier(page_to_nid(page)) && node_is_toptier(node))
>> +		if (!node_is_toptier(folio_nid(folio)) && node_is_toptier(node))
>>  			mod_node_page_state(pgdat, PGPROMOTE_SUCCESS,
>>  					    nr_succeeded);
>>  	}
>> @@ -2569,7 +2570,7 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
>>  	return isolated;
>>
>>  out:
>> -	put_page(page);
>> +	folio_put(folio);
>>  	return 0;
>>  }
>>  #endif /* CONFIG_NUMA_BALANCING */
>> -- 
>> 2.41.0
>
>
> --
> Best Regards,
> Yan, Zi