diff mbox series

[-next,v2,1/7] mm: page_idle: Convert page idle to use folios

Message ID 20221227122714.161224-2-wangkefeng.wang@huawei.com (mailing list archive)
State New
Headers show
Series mm: convert page_idle/damon to use folios | expand

Commit Message

Kefeng Wang Dec. 27, 2022, 12:27 p.m. UTC 
Firtly, make page_idle_get_page() return a folio when successfully
grab a ref of a page, also rename it page_idle_get_folio(), then,
use it to covert page_idle_bitmap_read()/write() functions.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 mm/page_idle.c | 45 ++++++++++++++++++++++-----------------------
 1 file changed, 22 insertions(+), 23 deletions(-)

Comments

Matthew Wilcox Dec. 27, 2022, 6:14 p.m. UTC | #1 
On Tue, Dec 27, 2022 at 08:27:08PM +0800, Kefeng Wang wrote:
> -static struct page *page_idle_get_page(unsigned long pfn)
> +static struct folio *page_idle_get_folio(unsigned long pfn)
>  {
>  	struct page *page = pfn_to_online_page(pfn);
> +	struct folio *folio;
>  
> -	if (!page || !PageLRU(page) ||
> -	    !get_page_unless_zero(page))
> +	if (!page || !PageLRU(page) || !get_page_unless_zero(page))
>  		return NULL;

Mmmm, no.  PageLRU hides a compound_head() call.  Try doing this instead:

	if (!page || PageTail(page))
		return NULL;
	folio = page_folio(page);
	if (!folio_test_lru(folio) || !folio_try_get(folio))
		return NULL;
	if (page_folio(page) != folio || !folio_test_lru(folio)) {
		folio_put(folio);
		folio = NULL;
	}

	return NULL;
Kefeng Wang Dec. 28, 2022, 1:18 a.m. UTC | #2 
On 2022/12/28 2:14, Matthew Wilcox wrote:
> On Tue, Dec 27, 2022 at 08:27:08PM +0800, Kefeng Wang wrote:
>> -static struct page *page_idle_get_page(unsigned long pfn)
>> +static struct folio *page_idle_get_folio(unsigned long pfn)
>>   {
>>   	struct page *page = pfn_to_online_page(pfn);
>> +	struct folio *folio;
>>   
>> -	if (!page || !PageLRU(page) ||
>> -	    !get_page_unless_zero(page))
>> +	if (!page || !PageLRU(page) || !get_page_unless_zero(page))
>>   		return NULL;
> 
> Mmmm, no.  PageLRU hides a compound_head() call.  Try doing this instead:
> 
> 	if (!page || PageTail(page))
> 		return NULL;
> 	folio = page_folio(page);
> 	if (!folio_test_lru(folio) || !folio_try_get(folio))
> 		return NULL;
> 	if (page_folio(page) != folio || !folio_test_lru(folio)) {
> 		folio_put(folio);
> 		folio = NULL;
> 	}
> 
Thanks Matthew, this is more complete, will update.
> 	return NULL;
> 
>
diff mbox series

Patch

diff --git a/mm/page_idle.c b/mm/page_idle.c
index bc08332a609c..4f248e500e08 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -31,19 +31,20 @@ 
  *
  * This function tries to get a user memory page by pfn as described above.
  */
-static struct page *page_idle_get_page(unsigned long pfn)
+static struct folio *page_idle_get_folio(unsigned long pfn)
 {
 	struct page *page = pfn_to_online_page(pfn);
+	struct folio *folio;
 
-	if (!page || !PageLRU(page) ||
-	    !get_page_unless_zero(page))
+	if (!page || !PageLRU(page) || !get_page_unless_zero(page))
 		return NULL;
 
-	if (unlikely(!PageLRU(page))) {
-		put_page(page);
-		page = NULL;
+	folio = page_folio(page);
+	if (unlikely(!folio_test_lru(folio))) {
+		folio_put(folio);
+		folio = NULL;
 	}
-	return page;
+	return folio;
 }
 
 static bool page_idle_clear_pte_refs_one(struct folio *folio,
@@ -83,10 +84,8 @@  static bool page_idle_clear_pte_refs_one(struct folio *folio,
 	return true;
 }
 
-static void page_idle_clear_pte_refs(struct page *page)
+static void page_idle_clear_pte_refs(struct folio *folio)
 {
-	struct folio *folio = page_folio(page);
-
 	/*
 	 * Since rwc.try_lock is unused, rwc is effectively immutable, so we
 	 * can make it static to save some cycles and stack.
@@ -115,7 +114,7 @@  static ssize_t page_idle_bitmap_read(struct file *file, struct kobject *kobj,
 				     loff_t pos, size_t count)
 {
 	u64 *out = (u64 *)buf;
-	struct page *page;
+	struct folio *folio;
 	unsigned long pfn, end_pfn;
 	int bit;
 
@@ -134,19 +133,19 @@  static ssize_t page_idle_bitmap_read(struct file *file, struct kobject *kobj,
 		bit = pfn % BITMAP_CHUNK_BITS;
 		if (!bit)
 			*out = 0ULL;
-		page = page_idle_get_page(pfn);
-		if (page) {
-			if (page_is_idle(page)) {
+		folio = page_idle_get_folio(pfn);
+		if (folio) {
+			if (folio_test_idle(folio)) {
 				/*
 				 * The page might have been referenced via a
 				 * pte, in which case it is not idle. Clear
 				 * refs and recheck.
 				 */
-				page_idle_clear_pte_refs(page);
-				if (page_is_idle(page))
+				page_idle_clear_pte_refs(folio);
+				if (folio_test_idle(folio))
 					*out |= 1ULL << bit;
 			}
-			put_page(page);
+			folio_put(folio);
 		}
 		if (bit == BITMAP_CHUNK_BITS - 1)
 			out++;
@@ -160,7 +159,7 @@  static ssize_t page_idle_bitmap_write(struct file *file, struct kobject *kobj,
 				      loff_t pos, size_t count)
 {
 	const u64 *in = (u64 *)buf;
-	struct page *page;
+	struct folio *folio;
 	unsigned long pfn, end_pfn;
 	int bit;
 
@@ -178,11 +177,11 @@  static ssize_t page_idle_bitmap_write(struct file *file, struct kobject *kobj,
 	for (; pfn < end_pfn; pfn++) {
 		bit = pfn % BITMAP_CHUNK_BITS;
 		if ((*in >> bit) & 1) {
-			page = page_idle_get_page(pfn);
-			if (page) {
-				page_idle_clear_pte_refs(page);
-				set_page_idle(page);
-				put_page(page);
+			folio = page_idle_get_folio(pfn);
+			if (folio) {
+				page_idle_clear_pte_refs(folio);
+				folio_set_idle(folio);
+				folio_put(folio);
 			}
 		}
 		if (bit == BITMAP_CHUNK_BITS - 1)