[-next,v2,1/2] mm: compaction: convert to use a folio in isolate_migratepages_block()
Commit Message
Directly use a folio instead of page_folio() when page successfully
isolated (hugepage and movable page) and after folio_get_nontail_page(),
which removes several calls to compound_head().
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
v2:
- update comments and use node_stat_mod_folio, per Matthew Wilcox
- add missed PageLRU conversion and rebase on next-20230619
mm/compaction.c | 84 ++++++++++++++++++++++++++-----------------------
1 file changed, 44 insertions(+), 40 deletions(-)
Comments
Hi
On 6/19/2023 7:07 PM, Kefeng Wang wrote:
> Directly use a folio instead of page_folio() when page successfully
> isolated (hugepage and movable page) and after folio_get_nontail_page(),
> which removes several calls to compound_head().
>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
> v2:
> - update comments and use node_stat_mod_folio, per Matthew Wilcox
> - add missed PageLRU conversion and rebase on next-20230619
>
> mm/compaction.c | 84 ++++++++++++++++++++++++++-----------------------
> 1 file changed, 44 insertions(+), 40 deletions(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 6149a2d324be..0334eefe4bfa 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -795,6 +795,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
> struct lruvec *lruvec;
> unsigned long flags = 0;
> struct lruvec *locked = NULL;
> + struct folio *folio = NULL;
> struct page *page = NULL, *valid_page = NULL;
> struct address_space *mapping;
> unsigned long start_pfn = low_pfn;
> @@ -891,7 +892,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
> if (!valid_page && pageblock_aligned(low_pfn)) {
> if (!isolation_suitable(cc, page)) {
> low_pfn = end_pfn;
> - page = NULL;
> + folio = NULL;
> goto isolate_abort;
> }
> valid_page = page;
> @@ -923,7 +924,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
> * Hugepage was successfully isolated and placed
> * on the cc->migratepages list.
> */
> - low_pfn += compound_nr(page) - 1;
> + folio = page_folio(page);
> + low_pfn += folio_nr_pages(folio) - 1;
> goto isolate_success_no_list;
> }
>
> @@ -991,8 +993,10 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
> locked = NULL;
> }
>
> - if (isolate_movable_page(page, mode))
> + if (isolate_movable_page(page, mode)) {
> + folio = page_folio(page);
> goto isolate_success;
> + }
> }
>
> goto isolate_fail;
> @@ -1003,7 +1007,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
> * sure the page is not being freed elsewhere -- the
> * page release code relies on it.
> */
> - if (unlikely(!get_page_unless_zero(page)))
> + folio = folio_get_nontail_page(page);
I'm just curious, how can you make sure the 'page' is not a tail page?
Since the validation is lockless.
On 2023/6/21 14:20, Baolin Wang wrote:
> Hi
>
> On 6/19/2023 7:07 PM, Kefeng Wang wrote:
>> Directly use a folio instead of page_folio() when page successfully
>> isolated (hugepage and movable page) and after folio_get_nontail_page(),
>> which removes several calls to compound_head().
>>
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
>> ---
>> v2:
>> - update comments and use node_stat_mod_folio, per Matthew Wilcox
>> - add missed PageLRU conversion and rebase on next-20230619
>>
>> mm/compaction.c | 84 ++++++++++++++++++++++++++-----------------------
>> 1 file changed, 44 insertions(+), 40 deletions(-)
>>
>> diff --git a/mm/compaction.c b/mm/compaction.c
>> index 6149a2d324be..0334eefe4bfa 100644
>> --- a/mm/compaction.c
>> +++ b/mm/compaction.c
>> @@ -795,6 +795,7 @@ isolate_migratepages_block(struct compact_control
>> *cc, unsigned long low_pfn,
>> struct lruvec *lruvec;
>> unsigned long flags = 0;
>> struct lruvec *locked = NULL;
>> + struct folio *folio = NULL;
>> struct page *page = NULL, *valid_page = NULL;
>> struct address_space *mapping;
>> unsigned long start_pfn = low_pfn;
>> @@ -891,7 +892,7 @@ isolate_migratepages_block(struct compact_control
>> *cc, unsigned long low_pfn,
>> if (!valid_page && pageblock_aligned(low_pfn)) {
>> if (!isolation_suitable(cc, page)) {
>> low_pfn = end_pfn;
>> - page = NULL;
>> + folio = NULL;
>> goto isolate_abort;
>> }
>> valid_page = page;
>> @@ -923,7 +924,8 @@ isolate_migratepages_block(struct compact_control
>> *cc, unsigned long low_pfn,
>> * Hugepage was successfully isolated and placed
>> * on the cc->migratepages list.
>> */
>> - low_pfn += compound_nr(page) - 1;
>> + folio = page_folio(page);
>> + low_pfn += folio_nr_pages(folio) - 1;
>> goto isolate_success_no_list;
>> }
>> @@ -991,8 +993,10 @@ isolate_migratepages_block(struct compact_control
>> *cc, unsigned long low_pfn,
>> locked = NULL;
>> }
>> - if (isolate_movable_page(page, mode))
>> + if (isolate_movable_page(page, mode)) {
>> + folio = page_folio(page);
>> goto isolate_success;
>> + }
>> }
>> goto isolate_fail;
>> @@ -1003,7 +1007,8 @@ isolate_migratepages_block(struct
>> compact_control *cc, unsigned long low_pfn,
>> * sure the page is not being freed elsewhere -- the
>> * page release code relies on it.
>> */
>> - if (unlikely(!get_page_unless_zero(page)))
>> + folio = folio_get_nontail_page(page);
>
> I'm just curious, how can you make sure the 'page' is not a tail page?
> Since the validation is lockless.
folio_get_nontail_page is added by commit "3c1ea2c729ef (mm: add
folio_get_nontail_page())", see more comments [1]
[1] https://lore.kernel.org/lkml/Y86sRiKAAOz2myNe@casper.infradead.org/
>
On 6/21/2023 4:36 PM, Kefeng Wang wrote:
>
>
> On 2023/6/21 14:20, Baolin Wang wrote:
>> Hi
>>
>> On 6/19/2023 7:07 PM, Kefeng Wang wrote:
>>> Directly use a folio instead of page_folio() when page successfully
>>> isolated (hugepage and movable page) and after folio_get_nontail_page(),
>>> which removes several calls to compound_head().
>>>
>>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
>>> ---
>>> v2:
>>> - update comments and use node_stat_mod_folio, per Matthew Wilcox
>>> - add missed PageLRU conversion and rebase on next-20230619
>>>
>>> mm/compaction.c | 84 ++++++++++++++++++++++++++-----------------------
>>> 1 file changed, 44 insertions(+), 40 deletions(-)
>>>
>>> diff --git a/mm/compaction.c b/mm/compaction.c
>>> index 6149a2d324be..0334eefe4bfa 100644
>>> --- a/mm/compaction.c
>>> +++ b/mm/compaction.c
>>> @@ -795,6 +795,7 @@ isolate_migratepages_block(struct compact_control
>>> *cc, unsigned long low_pfn,
>>> struct lruvec *lruvec;
>>> unsigned long flags = 0;
>>> struct lruvec *locked = NULL;
>>> + struct folio *folio = NULL;
>>> struct page *page = NULL, *valid_page = NULL;
>>> struct address_space *mapping;
>>> unsigned long start_pfn = low_pfn;
>>> @@ -891,7 +892,7 @@ isolate_migratepages_block(struct compact_control
>>> *cc, unsigned long low_pfn,
>>> if (!valid_page && pageblock_aligned(low_pfn)) {
>>> if (!isolation_suitable(cc, page)) {
>>> low_pfn = end_pfn;
>>> - page = NULL;
>>> + folio = NULL;
>>> goto isolate_abort;
>>> }
>>> valid_page = page;
>>> @@ -923,7 +924,8 @@ isolate_migratepages_block(struct compact_control
>>> *cc, unsigned long low_pfn,
>>> * Hugepage was successfully isolated and placed
>>> * on the cc->migratepages list.
>>> */
>>> - low_pfn += compound_nr(page) - 1;
>>> + folio = page_folio(page);
>>> + low_pfn += folio_nr_pages(folio) - 1;
>>> goto isolate_success_no_list;
>>> }
>>> @@ -991,8 +993,10 @@ isolate_migratepages_block(struct
>>> compact_control *cc, unsigned long low_pfn,
>>> locked = NULL;
>>> }
>>> - if (isolate_movable_page(page, mode))
>>> + if (isolate_movable_page(page, mode)) {
>>> + folio = page_folio(page);
>>> goto isolate_success;
>>> + }
>>> }
>>> goto isolate_fail;
>>> @@ -1003,7 +1007,8 @@ isolate_migratepages_block(struct
>>> compact_control *cc, unsigned long low_pfn,
>>> * sure the page is not being freed elsewhere -- the
>>> * page release code relies on it.
>>> */
>>> - if (unlikely(!get_page_unless_zero(page)))
>>> + folio = folio_get_nontail_page(page);
>>
>> I'm just curious, how can you make sure the 'page' is not a tail page?
>> Since the validation is lockless.
>
> folio_get_nontail_page is added by commit "3c1ea2c729ef (mm: add
> folio_get_nontail_page())", see more comments [1]
>
> [1] https://lore.kernel.org/lkml/Y86sRiKAAOz2myNe@casper.infradead.org/
I see. Thanks for sharing. The changes look good to me at least. Please
feel free to add:
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
@@ -795,6 +795,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
struct lruvec *lruvec;
unsigned long flags = 0;
struct lruvec *locked = NULL;
+ struct folio *folio = NULL;
struct page *page = NULL, *valid_page = NULL;
struct address_space *mapping;
unsigned long start_pfn = low_pfn;
@@ -891,7 +892,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
if (!valid_page && pageblock_aligned(low_pfn)) {
if (!isolation_suitable(cc, page)) {
low_pfn = end_pfn;
- page = NULL;
+ folio = NULL;
goto isolate_abort;
}
valid_page = page;
@@ -923,7 +924,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
* Hugepage was successfully isolated and placed
* on the cc->migratepages list.
*/
- low_pfn += compound_nr(page) - 1;
+ folio = page_folio(page);
+ low_pfn += folio_nr_pages(folio) - 1;
goto isolate_success_no_list;
}
@@ -991,8 +993,10 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
locked = NULL;
}
- if (isolate_movable_page(page, mode))
+ if (isolate_movable_page(page, mode)) {
+ folio = page_folio(page);
goto isolate_success;
+ }
}
goto isolate_fail;
@@ -1003,7 +1007,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
* sure the page is not being freed elsewhere -- the
* page release code relies on it.
*/
- if (unlikely(!get_page_unless_zero(page)))
+ folio = folio_get_nontail_page(page);
+ if (unlikely(!folio))
goto isolate_fail;
/*
@@ -1011,8 +1016,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
* so avoid taking lru_lock and isolating it unnecessarily in an
* admittedly racy check.
*/
- mapping = page_mapping(page);
- if (!mapping && (page_count(page) - 1) > total_mapcount(page))
+ mapping = folio_mapping(folio);
+ if (!mapping && (folio_ref_count(folio) - 1) > folio_mapcount(folio))
goto isolate_fail_put;
/*
@@ -1023,11 +1028,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
goto isolate_fail_put;
/* Only take pages on LRU: a check now makes later tests safe */
- if (!PageLRU(page))
+ if (!folio_test_lru(folio))
goto isolate_fail_put;
/* Compaction might skip unevictable pages but CMA takes them */
- if (!(mode & ISOLATE_UNEVICTABLE) && PageUnevictable(page))
+ if (!(mode & ISOLATE_UNEVICTABLE) && folio_test_unevictable(folio))
goto isolate_fail_put;
/*
@@ -1036,10 +1041,10 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
* it will be able to migrate without blocking - clean pages
* for the most part. PageWriteback would require blocking.
*/
- if ((mode & ISOLATE_ASYNC_MIGRATE) && PageWriteback(page))
+ if ((mode & ISOLATE_ASYNC_MIGRATE) && folio_test_writeback(folio))
goto isolate_fail_put;
- if ((mode & ISOLATE_ASYNC_MIGRATE) && PageDirty(page)) {
+ if ((mode & ISOLATE_ASYNC_MIGRATE) && folio_test_dirty(folio)) {
bool migrate_dirty;
/*
@@ -1051,22 +1056,22 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
* the page lock until after the page is removed
* from the page cache.
*/
- if (!trylock_page(page))
+ if (!folio_trylock(folio))
goto isolate_fail_put;
- mapping = page_mapping(page);
+ mapping = folio_mapping(folio);
migrate_dirty = !mapping ||
mapping->a_ops->migrate_folio;
- unlock_page(page);
+ folio_unlock(folio);
if (!migrate_dirty)
goto isolate_fail_put;
}
- /* Try isolate the page */
- if (!TestClearPageLRU(page))
+ /* Try isolate the folio */
+ if (!folio_test_clear_lru(folio))
goto isolate_fail_put;
- lruvec = folio_lruvec(page_folio(page));
+ lruvec = folio_lruvec(folio);
/* If we already hold the lock, we can skip some rechecking */
if (lruvec != locked) {
@@ -1076,7 +1081,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
compact_lock_irqsave(&lruvec->lru_lock, &flags, cc);
locked = lruvec;
- lruvec_memcg_debug(lruvec, page_folio(page));
+ lruvec_memcg_debug(lruvec, folio);
/*
* Try get exclusive access under lock. If marked for
@@ -1092,34 +1097,33 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
}
/*
- * Page become compound since the non-locked check,
- * and it's on LRU. It can only be a THP so the order
- * is safe to read and it's 0 for tail pages.
+ * folio become large since the non-locked check,
+ * and it's on LRU.
*/
- if (unlikely(PageCompound(page) && !cc->alloc_contig)) {
- low_pfn += compound_nr(page) - 1;
- nr_scanned += compound_nr(page) - 1;
- SetPageLRU(page);
+ if (unlikely(folio_test_large(folio) && !cc->alloc_contig)) {
+ low_pfn += folio_nr_pages(folio) - 1;
+ nr_scanned += folio_nr_pages(folio) - 1;
+ folio_set_lru(folio);
goto isolate_fail_put;
}
}
- /* The whole page is taken off the LRU; skip the tail pages. */
- if (PageCompound(page))
- low_pfn += compound_nr(page) - 1;
+ /* The folio is taken off the LRU */
+ if (folio_test_large(folio))
+ low_pfn += folio_nr_pages(folio) - 1;
/* Successfully isolated */
- del_page_from_lru_list(page, lruvec);
- mod_node_page_state(page_pgdat(page),
- NR_ISOLATED_ANON + page_is_file_lru(page),
- thp_nr_pages(page));
+ lruvec_del_folio(lruvec, folio);
+ node_stat_mod_folio(folio,
+ NR_ISOLATED_ANON + folio_is_file_lru(folio),
+ folio_nr_pages(folio));
isolate_success:
- list_add(&page->lru, &cc->migratepages);
+ list_add(&folio->lru, &cc->migratepages);
isolate_success_no_list:
- cc->nr_migratepages += compound_nr(page);
- nr_isolated += compound_nr(page);
- nr_scanned += compound_nr(page) - 1;
+ cc->nr_migratepages += folio_nr_pages(folio);
+ nr_isolated += folio_nr_pages(folio);
+ nr_scanned += folio_nr_pages(folio) - 1;
/*
* Avoid isolating too much unless this block is being
@@ -1141,7 +1145,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
unlock_page_lruvec_irqrestore(locked, flags);
locked = NULL;
}
- put_page(page);
+ folio_put(folio);
isolate_fail:
if (!skip_on_failure && ret != -ENOMEM)
@@ -1182,14 +1186,14 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
if (unlikely(low_pfn > end_pfn))
low_pfn = end_pfn;
- page = NULL;
+ folio = NULL;
isolate_abort:
if (locked)
unlock_page_lruvec_irqrestore(locked, flags);
- if (page) {
- SetPageLRU(page);
- put_page(page);
+ if (folio) {
+ folio_set_lru(folio);
+ folio_put(folio);
}
/*