[PATCH v2 0/3] Small hugetlb cleanups

[PATCH v2 0/3] Small hugetlb cleanups

[Matthew Wilcox (Oracle)]

Some trivial folio conveersions

v2:
 - collect R-b tags
 - Rename remove_pool_huge_page to remove_pool_hugetlb_folio
 - Fix uninitialised pointer usage reported by lkp@intel.com

Matthew Wilcox (Oracle) (3):
  hugetlb: Use a folio in free_hpage_workfn()
  hugetlb: Remove a few calls to page_folio()
  hugetlb: Convert remove_pool_huge_page() to
    remove_pool_hugetlb_folio()

 mm/hugetlb.c | 65 +++++++++++++++++++++++++---------------------------
 1 file changed, 31 insertions(+), 34 deletions(-)

-- 
2.40.1

[PATCH v2 1/3] hugetlb: Use a folio in free_hpage_workfn()

[Matthew Wilcox (Oracle)]

update_and_free_hugetlb_folio puts the memory on hpage_freelist as a folio
so we can take it off the list as a folio.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
---
 mm/hugetlb.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a82c3104337e..d1c856628bac 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1786,22 +1786,22 @@ static void free_hpage_workfn(struct work_struct *work)
 	node = llist_del_all(&hpage_freelist);
 
 	while (node) {
-		struct page *page;
+		struct folio *folio;
 		struct hstate *h;
 
-		page = container_of((struct address_space **)node,
-				     struct page, mapping);
+		folio = container_of((struct address_space **)node,
+				     struct folio, mapping);
 		node = node->next;
-		page->mapping = NULL;
+		folio->mapping = NULL;
 		/*
 		 * The VM_BUG_ON_FOLIO(!folio_test_hugetlb(folio), folio) in
 		 * folio_hstate() is going to trigger because a previous call to
 		 * remove_hugetlb_folio() will clear the hugetlb bit, so do
 		 * not use folio_hstate() directly.
 		 */
-		h = size_to_hstate(page_size(page));
+		h = size_to_hstate(folio_size(folio));
 
-		__update_and_free_hugetlb_folio(h, page_folio(page));
+		__update_and_free_hugetlb_folio(h, folio);
 
 		cond_resched();
 	}
-- 
2.40.1

[PATCH v2 2/3] hugetlb: Remove a few calls to page_folio()

[Matthew Wilcox (Oracle)]

Anything found on a linked list threaded through ->lru is guaranteed to
be a folio as the compound_head found in a tail page overlaps the ->lru
member of struct page.  So we can pull folios directly off these lists
no matter whether pages or folios were added to the list.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
---
 mm/hugetlb.c | 26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index d1c856628bac..8f548a274e3c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1835,11 +1835,9 @@ static void update_and_free_hugetlb_folio(struct hstate *h, struct folio *folio,
 
 static void update_and_free_pages_bulk(struct hstate *h, struct list_head *list)
 {
-	struct page *page, *t_page;
-	struct folio *folio;
+	struct folio *folio, *t_folio;
 
-	list_for_each_entry_safe(page, t_page, list, lru) {
-		folio = page_folio(page);
+	list_for_each_entry_safe(folio, t_folio, list, lru) {
 		update_and_free_hugetlb_folio(h, folio, false);
 		cond_resched();
 	}
@@ -2228,8 +2226,7 @@ static struct page *remove_pool_huge_page(struct hstate *h,
 						 bool acct_surplus)
 {
 	int nr_nodes, node;
-	struct page *page = NULL;
-	struct folio *folio;
+	struct folio *folio = NULL;
 
 	lockdep_assert_held(&hugetlb_lock);
 	for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
@@ -2239,15 +2236,14 @@ static struct page *remove_pool_huge_page(struct hstate *h,
 		 */
 		if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
 		    !list_empty(&h->hugepage_freelists[node])) {
-			page = list_entry(h->hugepage_freelists[node].next,
-					  struct page, lru);
-			folio = page_folio(page);
+			folio = list_entry(h->hugepage_freelists[node].next,
+					  struct folio, lru);
 			remove_hugetlb_folio(h, folio, acct_surplus);
 			break;
 		}
 	}
 
-	return page;
+	return &folio->page;
 }
 
 /*
@@ -3363,15 +3359,15 @@ static void try_to_free_low(struct hstate *h, unsigned long count,
 	 * Collect pages to be freed on a list, and free after dropping lock
 	 */
 	for_each_node_mask(i, *nodes_allowed) {
-		struct page *page, *next;
+		struct folio *folio, *next;
 		struct list_head *freel = &h->hugepage_freelists[i];
-		list_for_each_entry_safe(page, next, freel, lru) {
+		list_for_each_entry_safe(folio, next, freel, lru) {
 			if (count >= h->nr_huge_pages)
 				goto out;
-			if (PageHighMem(page))
+			if (folio_test_highmem(folio))
 				continue;
-			remove_hugetlb_folio(h, page_folio(page), false);
-			list_add(&page->lru, &page_list);
+			remove_hugetlb_folio(h, folio, false);
+			list_add(&folio->lru, &page_list);
 		}
 	}
 
-- 
2.40.1

[PATCH v2 3/3] hugetlb: Convert remove_pool_huge_page() to remove_pool_hugetlb_folio()

[Matthew Wilcox (Oracle)]

Convert the callers to expect a folio and remove the unnecesary conversion
back to a struct page.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
---
 mm/hugetlb.c | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 8f548a274e3c..35dcc7f9b52a 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1441,7 +1441,7 @@ static int hstate_next_node_to_alloc(struct hstate *h,
 }
 
 /*
- * helper for remove_pool_huge_page() - return the previously saved
+ * helper for remove_pool_hugetlb_folio() - return the previously saved
  * node ["this node"] from which to free a huge page.  Advance the
  * next node id whether or not we find a free huge page to free so
  * that the next attempt to free addresses the next node.
@@ -2221,9 +2221,8 @@ static int alloc_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
  * an additional call to free the page to low level allocators.
  * Called with hugetlb_lock locked.
  */
-static struct page *remove_pool_huge_page(struct hstate *h,
-						nodemask_t *nodes_allowed,
-						 bool acct_surplus)
+static struct folio *remove_pool_hugetlb_folio(struct hstate *h,
+		nodemask_t *nodes_allowed, bool acct_surplus)
 {
 	int nr_nodes, node;
 	struct folio *folio = NULL;
@@ -2243,7 +2242,7 @@ static struct page *remove_pool_huge_page(struct hstate *h,
 		}
 	}
 
-	return &folio->page;
+	return folio;
 }
 
 /*
@@ -2597,7 +2596,6 @@ static void return_unused_surplus_pages(struct hstate *h,
 					unsigned long unused_resv_pages)
 {
 	unsigned long nr_pages;
-	struct page *page;
 	LIST_HEAD(page_list);
 
 	lockdep_assert_held(&hugetlb_lock);
@@ -2618,15 +2616,17 @@ static void return_unused_surplus_pages(struct hstate *h,
 	 * evenly across all nodes with memory. Iterate across these nodes
 	 * until we can no longer free unreserved surplus pages. This occurs
 	 * when the nodes with surplus pages have no free pages.
-	 * remove_pool_huge_page() will balance the freed pages across the
+	 * remove_pool_hugetlb_folio() will balance the freed pages across the
 	 * on-line nodes with memory and will handle the hstate accounting.
 	 */
 	while (nr_pages--) {
-		page = remove_pool_huge_page(h, &node_states[N_MEMORY], 1);
-		if (!page)
+		struct folio *folio;
+
+		folio = remove_pool_hugetlb_folio(h, &node_states[N_MEMORY], 1);
+		if (!folio)
 			goto out;
 
-		list_add(&page->lru, &page_list);
+		list_add(&folio->lru, &page_list);
 	}
 
 out:
@@ -3421,7 +3421,6 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
 			      nodemask_t *nodes_allowed)
 {
 	unsigned long min_count, ret;
-	struct page *page;
 	LIST_HEAD(page_list);
 	NODEMASK_ALLOC(nodemask_t, node_alloc_noretry, GFP_KERNEL);
 
@@ -3541,11 +3540,13 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
 	 * Collect pages to be removed on list without dropping lock
 	 */
 	while (min_count < persistent_huge_pages(h)) {
-		page = remove_pool_huge_page(h, nodes_allowed, 0);
-		if (!page)
+		struct folio *folio;
+
+		folio = remove_pool_hugetlb_folio(h, nodes_allowed, 0);
+		if (!folio)
 			break;
 
-		list_add(&page->lru, &page_list);
+		list_add(&folio->lru, &page_list);
 	}
 	/* free the pages after dropping lock */
 	spin_unlock_irq(&hugetlb_lock);
-- 
2.40.1

Re: [PATCH v2 3/3] hugetlb: Convert remove_pool_huge_page() to remove_pool_hugetlb_folio()

[Muchun Song]

> On Aug 24, 2023, at 22:13, Matthew Wilcox (Oracle) <willy@infradead.org> wrote:
> 
> Convert the callers to expect a folio and remove the unnecesary conversion
> back to a struct page.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
> Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>

Reviewed-by: Muchun Song <songmuchun@bytedance.com>

Thanks.