[PATCH v13 062/137] mm/migrate: Add folio_migrate_copy()

Matthew Wilcox (Oracle)
2021-07-12T03:41:05Z

Combine the THP, hugetlb and base page routines together into a simple
loop.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
include/linux/migrate.h | 1 +
mm/folio-compat.c | 6 ++++
mm/migrate.c | 67 +++++++----------------------------------
3 files changed, 18 insertions(+), 56 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index b9cd88915c6b..e8db1d87f1f1 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -53,6 +53,7 @@ extern int migrate_page_move_mapping(struct address_space *mapping,
struct page *newpage, struct page *page, int extra_count);
extern void copy_huge_page(struct page *dst, struct page *src);
void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
+void folio_migrate_copy(struct folio *newfolio, struct folio *folio);
int folio_migrate_mapping(struct address_space *mapping,
struct folio *newfolio, struct folio *folio, int extra_count);
#else
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index 3f00ad92d1ff..2ccd8f213fc4 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -64,4 +64,10 @@ void migrate_page_states(struct page *newpage, struct page *page)
folio_migrate_flags(page_folio(newpage), page_folio(page));
}
EXPORT_SYMBOL(migrate_page_states);
+
+void migrate_page_copy(struct page *newpage, struct page *page)
+{
+ folio_migrate_copy(page_folio(newpage), page_folio(page));
+}
+EXPORT_SYMBOL(migrate_page_copy);
#endif
diff --git a/mm/migrate.c b/mm/migrate.c
index c16923052e13..942a5ce11f39 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -537,54 +537,6 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
return MIGRATEPAGE_SUCCESS;
}

-/*
- * Gigantic pages are so large that we do not guarantee that page++ pointer
- * arithmetic will work across the entire page. We need something more
- * specialized.
- */
-static void __copy_gigantic_page(struct page *dst, struct page *src,
- int nr_pages)
-{
- int i;
- struct page *dst_base = dst;
- struct page *src_base = src;
-
- for (i = 0; i < nr_pages; ) {
- cond_resched();
- copy_highpage(dst, src);
-
- i++;
- dst = mem_map_next(dst, dst_base, i);
- src = mem_map_next(src, src_base, i);
- }
-}
-
-void copy_huge_page(struct page *dst, struct page *src)
-{
- int i;
- int nr_pages;
-
- if (PageHuge(src)) {
- /* hugetlbfs page */
- struct hstate *h = page_hstate(src);
- nr_pages = pages_per_huge_page(h);
-
- if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) {
- __copy_gigantic_page(dst, src, nr_pages);
- return;
- }
- } else {
- /* thp page */
- BUG_ON(!PageTransHuge(src));
- nr_pages = thp_nr_pages(src);
- }
-
- for (i = 0; i < nr_pages; i++) {
- cond_resched();
- copy_highpage(dst + i, src + i);
- }
-}
-
/*
* Copy the flags and some other ancillary information
*/
@@ -661,16 +613,19 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
}
EXPORT_SYMBOL(folio_migrate_flags);

-void migrate_page_copy(struct page *newpage, struct page *page)
+void folio_migrate_copy(struct folio *newfolio, struct folio *folio)
{
- if (PageHuge(page) || PageTransHuge(page))
- copy_huge_page(newpage, page);
- else
- copy_highpage(newpage, page);
+ unsigned int i, nr = folio_nr_pages(folio);

- migrate_page_states(newpage, page);
+ for (i = 0; i < nr; i++) {
+ /* folio_page() handles discontinuities in memmap */
+ copy_highpage(folio_page(newfolio, i), folio_page(folio, i));
+ cond_resched();
+ }
+
+ folio_migrate_flags(newfolio, folio);
}
-EXPORT_SYMBOL(migrate_page_copy);
+EXPORT_SYMBOL(folio_migrate_copy);

/************************************************************
* Migration functions
@@ -698,7 +653,7 @@ int migrate_page(struct address_space *mapping,
return rc;

if (mode != MIGRATE_SYNC_NO_COPY)
- migrate_page_copy(newpage, page);
+ folio_migrate_copy(newfolio, folio);
else
folio_migrate_flags(newfolio, folio);
return MIGRATEPAGE_SUCCESS;
--
2.30.2