[PATCH v13 060/137] mm/migrate: Add folio_migrate_mapping()

Matthew Wilcox (Oracle)
2021-07-12T03:40:03Z

Reimplement migrate_page_move_mapping() as a wrapper around
folio_migrate_mapping(). Saves 193 bytes of kernel text.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
include/linux/migrate.h | 2 +
mm/folio-compat.c | 11 ++++++
mm/migrate.c | 85 +++++++++++++++++++++--------------------
3 files changed, 57 insertions(+), 41 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 9b7b7cd3bae9..52bf62763205 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -52,6 +52,8 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping,
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);
+int folio_migrate_mapping(struct address_space *mapping,
+ struct folio *newfolio, struct folio *folio, int extra_count);
#else

static inline void putback_movable_pages(struct list_head *l) {}
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index a374747ae1c6..d883d964fd52 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -4,6 +4,7 @@
* eventually.
*/

+#include <linux/migrate.h>
#include <linux/pagemap.h>
#include <linux/swap.h>

@@ -48,3 +49,13 @@ void mark_page_accessed(struct page *page)
folio_mark_accessed(page_folio(page));
}
EXPORT_SYMBOL(mark_page_accessed);
+
+#ifdef CONFIG_MIGRATION
+int migrate_page_move_mapping(struct address_space *mapping,
+ struct page *newpage, struct page *page, int extra_count)
+{
+ return folio_migrate_mapping(mapping, page_folio(newpage),
+ page_folio(page), extra_count);
+}
+EXPORT_SYMBOL(migrate_page_move_mapping);
+#endif
diff --git a/mm/migrate.c b/mm/migrate.c
index d8df117dca7e..19dd053b4a52 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -363,7 +363,7 @@ static int expected_page_refs(struct address_space *mapping, struct page *page)
*/
expected_count += is_device_private_page(page);
if (mapping)
- expected_count += thp_nr_pages(page) + page_has_private(page);
+ expected_count += compound_nr(page) + page_has_private(page);

return expected_count;
}
@@ -376,74 +376,75 @@ static int expected_page_refs(struct address_space *mapping, struct page *page)
* 2 for pages with a mapping
* 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
*/
-int migrate_page_move_mapping(struct address_space *mapping,
- struct page *newpage, struct page *page, int extra_count)
+int folio_migrate_mapping(struct address_space *mapping,
+ struct folio *newfolio, struct folio *folio, int extra_count)
{
- XA_STATE(xas, &mapping->i_pages, page_index(page));
+ XA_STATE(xas, &mapping->i_pages, folio_index(folio));
struct zone *oldzone, *newzone;
int dirty;
- int expected_count = expected_page_refs(mapping, page) + extra_count;
- int nr = thp_nr_pages(page);
+ int expected_count = expected_page_refs(mapping, &folio->page) + extra_count;
+ int nr = folio_nr_pages(folio);

if (!mapping) {
/* Anonymous page without mapping */
- if (page_count(page) != expected_count)
+ if (folio_ref_count(folio) != expected_count)
return -EAGAIN;

/* No turning back from here */
- newpage->index = page->index;
- newpage->mapping = page->mapping;
- if (PageSwapBacked(page))
- __SetPageSwapBacked(newpage);
+ newfolio->index = folio->index;
+ newfolio->mapping = folio->mapping;
+ if (folio_swapbacked(folio))
+ __folio_set_swapbacked_flag(newfolio);

return MIGRATEPAGE_SUCCESS;
}

- oldzone = page_zone(page);
- newzone = page_zone(newpage);
+ oldzone = folio_zone(folio);
+ newzone = folio_zone(newfolio);

xas_lock_irq(&xas);
- if (page_count(page) != expected_count || xas_load(&xas) != page) {
+ if (folio_ref_count(folio) != expected_count ||
+ xas_load(&xas) != folio) {
xas_unlock_irq(&xas);
return -EAGAIN;
}

- if (!page_ref_freeze(page, expected_count)) {
+ if (!folio_ref_freeze(folio, expected_count)) {
xas_unlock_irq(&xas);
return -EAGAIN;
}

/*
- * Now we know that no one else is looking at the page:
+ * Now we know that no one else is looking at the folio:
* no turning back from here.
*/
- newpage->index = page->index;
- newpage->mapping = page->mapping;
- page_ref_add(newpage, nr); /* add cache reference */
- if (PageSwapBacked(page)) {
- __SetPageSwapBacked(newpage);
- if (PageSwapCache(page)) {
- SetPageSwapCache(newpage);
- set_page_private(newpage, page_private(page));
+ newfolio->index = folio->index;
+ newfolio->mapping = folio->mapping;
+ folio_ref_add(newfolio, nr); /* add cache reference */
+ if (folio_swapbacked(folio)) {
+ __folio_set_swapbacked_flag(newfolio);
+ if (folio_swapcache(folio)) {
+ folio_set_swapcache_flag(newfolio);
+ newfolio->private = folio_get_private(folio);
}
} else {
- VM_BUG_ON_PAGE(PageSwapCache(page), page);
+ VM_BUG_ON_FOLIO(folio_swapcache(folio), folio);
}

/* Move dirty while page refs frozen and newpage not yet exposed */
- dirty = PageDirty(page);
+ dirty = folio_dirty(folio);
if (dirty) {
- ClearPageDirty(page);
- SetPageDirty(newpage);
+ folio_clear_dirty_flag(folio);
+ folio_set_dirty_flag(newfolio);
}

- xas_store(&xas, newpage);
- if (PageTransHuge(page)) {
+ xas_store(&xas, newfolio);
+ if (nr > 1) {
int i;

for (i = 1; i < nr; i++) {
xas_next(&xas);
- xas_store(&xas, newpage);
+ xas_store(&xas, newfolio);
}
}

@@ -452,7 +453,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
* to one less reference.
* We know this isn't the last reference.
*/
- page_ref_unfreeze(page, expected_count - nr);
+ folio_ref_unfreeze(folio, expected_count - nr);

xas_unlock(&xas);
/* Leave irq disabled to prevent preemption while updating stats */
@@ -471,18 +472,18 @@ int migrate_page_move_mapping(struct address_space *mapping,
struct lruvec *old_lruvec, *new_lruvec;
struct mem_cgroup *memcg;

- memcg = page_memcg(page);
+ memcg = folio_memcg(folio);
old_lruvec = mem_cgroup_lruvec(memcg, oldzone->zone_pgdat);
new_lruvec = mem_cgroup_lruvec(memcg, newzone->zone_pgdat);

__mod_lruvec_state(old_lruvec, NR_FILE_PAGES, -nr);
__mod_lruvec_state(new_lruvec, NR_FILE_PAGES, nr);
- if (PageSwapBacked(page) && !PageSwapCache(page)) {
+ if (folio_swapbacked(folio) && !folio_swapcache(folio)) {
__mod_lruvec_state(old_lruvec, NR_SHMEM, -nr);
__mod_lruvec_state(new_lruvec, NR_SHMEM, nr);
}
#ifdef CONFIG_SWAP
- if (PageSwapCache(page)) {
+ if (folio_swapcache(folio)) {
__mod_lruvec_state(old_lruvec, NR_SWAPCACHE, -nr);
__mod_lruvec_state(new_lruvec, NR_SWAPCACHE, nr);
}
@@ -498,11 +499,11 @@ int migrate_page_move_mapping(struct address_space *mapping,

return MIGRATEPAGE_SUCCESS;
}
-EXPORT_SYMBOL(migrate_page_move_mapping);
+EXPORT_SYMBOL(folio_migrate_mapping);

/*
* The expected number of remaining references is the same as that
- * of migrate_page_move_mapping().
+ * of folio_migrate_mapping().
*/
int migrate_huge_page_move_mapping(struct address_space *mapping,
struct page *newpage, struct page *page)
@@ -611,7 +612,7 @@ void migrate_page_states(struct page *newpage, struct page *page)
if (PageMappedToDisk(page))
SetPageMappedToDisk(newpage);

- /* Move dirty on pages not done by migrate_page_move_mapping() */
+ /* Move dirty on pages not done by folio_migrate_mapping() */
if (PageDirty(page))
SetPageDirty(newpage);

@@ -687,11 +688,13 @@ int migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page,
enum migrate_mode mode)
{
+ struct folio *newfolio = page_folio(newpage);
+ struct folio *folio = page_folio(page);
int rc;

- BUG_ON(PageWriteback(page)); /* Writeback must be complete */
+ BUG_ON(folio_writeback(folio)); /* Writeback must be complete */

- rc = migrate_page_move_mapping(mapping, newpage, page, 0);
+ rc = folio_migrate_mapping(mapping, newfolio, folio, 0);

if (rc != MIGRATEPAGE_SUCCESS)
return rc;
@@ -2435,7 +2438,7 @@ static void migrate_vma_collect(struct migrate_vma *migrate)
* @page: struct page to check
*
* Pinned pages cannot be migrated. This is the same test as in
- * migrate_page_move_mapping(), except that here we allow migration of a
+ * folio_migrate_mapping(), except that here we allow migration of a
* ZONE_DEVICE page.
*/
static bool migrate_vma_check_page(struct page *page)
--
2.30.2