[PATCH v3 3/4] mm: hugetlb: change to return bool for isolate_hugetlb()

[Baolin Wang]

Now the isolate_hugetlb() only returns 0 or -EBUSY, and most users did not
care about the negative value, thus we can convert the isolate_hugetlb()
to return a boolean value to make code more clear when checking the
hugetlb isolation state. Moreover converts 2 users which will consider
the negative value returned by isolate_hugetlb().

No functional changes intended.

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
---
 include/linux/hugetlb.h |  6 +++---
 mm/hugetlb.c            | 13 ++++++++-----
 mm/memory-failure.c     |  2 +-
 mm/mempolicy.c          |  2 +-
 mm/migrate.c            |  7 +++----
 5 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index df6dd624ccfe..5f5e4177b2e0 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -171,7 +171,7 @@ bool hugetlb_reserve_pages(struct inode *inode, long from, long to,
 						vm_flags_t vm_flags);
 long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
 						long freed);
-int isolate_hugetlb(struct folio *folio, struct list_head *list);
+bool isolate_hugetlb(struct folio *folio, struct list_head *list);
 int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb, bool unpoison);
 int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
 				bool *migratable_cleared);
@@ -413,9 +413,9 @@ static inline pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr,
 	return NULL;
 }
 
-static inline int isolate_hugetlb(struct folio *folio, struct list_head *list)
+static inline bool isolate_hugetlb(struct folio *folio, struct list_head *list)
 {
-	return -EBUSY;
+	return false;
 }
 
 static inline int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb, bool unpoison)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3a01a9dbf445..16513cd23d5d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2925,13 +2925,16 @@ static int alloc_and_dissolve_hugetlb_folio(struct hstate *h,
 		 */
 		goto free_new;
 	} else if (folio_ref_count(old_folio)) {
+		bool isolated;
+
 		/*
 		 * Someone has grabbed the folio, try to isolate it here.
 		 * Fail with -EBUSY if not possible.
 		 */
 		spin_unlock_irq(&hugetlb_lock);
-		ret = isolate_hugetlb(old_folio, list);
+		isolated = isolate_hugetlb(old_folio, list);
 		spin_lock_irq(&hugetlb_lock);
+		ret = isolated ? 0 : -EBUSY;
 		goto free_new;
 	} else if (!folio_test_hugetlb_freed(old_folio)) {
 		/*
@@ -3005,7 +3008,7 @@ int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list)
 	if (hstate_is_gigantic(h))
 		return -ENOMEM;
 
-	if (folio_ref_count(folio) && !isolate_hugetlb(folio, list))
+	if (folio_ref_count(folio) && isolate_hugetlb(folio, list))
 		ret = 0;
 	else if (!folio_ref_count(folio))
 		ret = alloc_and_dissolve_hugetlb_folio(h, folio, list);
@@ -7251,15 +7254,15 @@ __weak unsigned long hugetlb_mask_last_page(struct hstate *h)
  * These functions are overwritable if your architecture needs its own
  * behavior.
  */
-int isolate_hugetlb(struct folio *folio, struct list_head *list)
+bool isolate_hugetlb(struct folio *folio, struct list_head *list)
 {
-	int ret = 0;
+	bool ret = true;
 
 	spin_lock_irq(&hugetlb_lock);
 	if (!folio_test_hugetlb(folio) ||
 	    !folio_test_hugetlb_migratable(folio) ||
 	    !folio_try_get(folio)) {
-		ret = -EBUSY;
+		ret = false;
 		goto unlock;
 	}
 	folio_clear_hugetlb_migratable(folio);
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index e504362fdb23..8604753bc644 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2508,7 +2508,7 @@ static bool isolate_page(struct page *page, struct list_head *pagelist)
 	bool isolated = false;
 
 	if (PageHuge(page)) {
-		isolated = !isolate_hugetlb(page_folio(page), pagelist);
+		isolated = isolate_hugetlb(page_folio(page), pagelist);
 	} else {
 		bool lru = !__PageMovable(page);
 
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 2751bc3310fd..a256a241fd1d 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -609,7 +609,7 @@ static int queue_folios_hugetlb(pte_t *pte, unsigned long hmask,
 	if (flags & (MPOL_MF_MOVE_ALL) ||
 	    (flags & MPOL_MF_MOVE && folio_estimated_sharers(folio) == 1 &&
 	     !hugetlb_pmd_shared(pte))) {
-		if (isolate_hugetlb(folio, qp->pagelist) &&
+		if (!isolate_hugetlb(folio, qp->pagelist) &&
 			(flags & MPOL_MF_STRICT))
 			/*
 			 * Failed to isolate folio but allow migrating pages
diff --git a/mm/migrate.c b/mm/migrate.c
index 53010a142e7f..2db546a0618c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2095,6 +2095,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
 	struct vm_area_struct *vma;
 	struct page *page;
 	int err;
+	bool isolated;
 
 	mmap_read_lock(mm);
 	err = -EFAULT;
@@ -2126,13 +2127,11 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
 
 	if (PageHuge(page)) {
 		if (PageHead(page)) {
-			err = isolate_hugetlb(page_folio(page), pagelist);
-			if (!err)
-				err = 1;
+			isolated = isolate_hugetlb(page_folio(page), pagelist);
+			err = isolated ? 1 : -EBUSY;
 		}
 	} else {
 		struct page *head;
-		bool isolated;
 
 		head = compound_head(page);
 		isolated = isolate_lru_page(head);
-- 
2.27.0