[PATCH] mm, hugetlb: fix allocation error check and copy func name

[Mina Almasry]

The alloc_huge_page_vma() doesn't return error pointers, it returns
NULL.

There is an existing migrate_page_copy() which not only copies the page
contents, but also page state/metadata.  People could get confused that
'migrate_page_copy' and 'migrate_copy_huge_page' do not have the same
functionality.  Rename to 'copy_huge_page()' to make it less likely
folks get confused.

Fixes: 6a0badc266df ("mm, hugetlb: fix racy resv_huge_pages underflow on
UFFDIO_COPY")

Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx

---
 include/linux/migrate.h | 4 ++--
 mm/hugetlb.c            | 4 ++--
 mm/migrate.c            | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index e0b98876a52e..9b7b7cd3bae9 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -51,7 +51,7 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping,
 				  struct page *newpage, struct page *page);
 extern int migrate_page_move_mapping(struct address_space *mapping,
 		struct page *newpage, struct page *page, int extra_count);
-extern void migrate_copy_huge_page(struct page *dst, struct page *src);
+extern void copy_huge_page(struct page *dst, struct page *src);
 #else

 static inline void putback_movable_pages(struct list_head *l) {}
@@ -78,7 +78,7 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
 	return -ENOSYS;
 }

-static inline void migrate_copy_huge_page(struct page *dst, struct page *src)
+static inline void copy_huge_page(struct page *dst, struct page *src)
 {
 }
 #endif /* CONFIG_MIGRATION */
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 64a460ff2d5b..637395907908 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5130,7 +5130,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
 			 * contents.
 			 */
 			page = alloc_huge_page_vma(h, dst_vma, dst_addr);
-			if (IS_ERR(page)) {
+			if (!page) {
 				ret = -ENOMEM;
 				goto out;
 			}
@@ -5156,7 +5156,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
 			*pagep = NULL;
 			goto out;
 		}
-		migrate_copy_huge_page(page, *pagep);
+		copy_huge_page(page, *pagep);
 		put_page(*pagep);
 		*pagep = NULL;
 	}
diff --git a/mm/migrate.c b/mm/migrate.c
index 2515210a9747..51f355757490 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -557,7 +557,7 @@ static void __copy_gigantic_page(struct page *dst, struct page *src,
 	}
 }

-void migrate_copy_huge_page(struct page *dst, struct page *src)
+void copy_huge_page(struct page *dst, struct page *src)
 {
 	int i;
 	int nr_pages;
@@ -662,7 +662,7 @@ EXPORT_SYMBOL(migrate_page_states);
 void migrate_page_copy(struct page *newpage, struct page *page)
 {
 	if (PageHuge(page) || PageTransHuge(page))
-		migrate_copy_huge_page(newpage, page);
+		copy_huge_page(newpage, page);
 	else
 		copy_highpage(newpage, page);

--
2.32.0.rc1.229.g3e70b5a671-goog