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Date: Wed, 20 Aug 2014 19:05:04 +0400
From: Konstantin Khlebnikov <k.khlebnikov@...sung.com>
To: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
Rafael Aquini <aquini@...hat.com>
Cc: Sasha Levin <sasha.levin@...cle.com>,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH 6/7] mm/balloon_compaction: use common page ballooning
This patch replaces checking AS_BALLOON_MAP in page->mapping->flags
with PageBalloon which is stored directly in the struct page.
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@...sung.com>
---
include/linux/balloon_compaction.h | 85 ++----------------------------------
mm/Kconfig | 2 -
mm/balloon_compaction.c | 7 +--
mm/compaction.c | 9 ++--
mm/migrate.c | 4 +-
mm/vmscan.c | 2 -
6 files changed, 15 insertions(+), 94 deletions(-)
diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
index 53d482e..f5fda8b 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -108,77 +108,6 @@ static inline void balloon_mapping_free(struct address_space *balloon_mapping)
}
/*
- * page_flags_cleared - helper to perform balloon @page ->flags tests.
- *
- * As balloon pages are obtained from buddy and we do not play with page->flags
- * at driver level (exception made when we get the page lock for compaction),
- * we can safely identify a ballooned page by checking if the
- * PAGE_FLAGS_CHECK_AT_PREP page->flags are all cleared. This approach also
- * helps us skip ballooned pages that are locked for compaction or release, thus
- * mitigating their racy check at balloon_page_movable()
- */
-static inline bool page_flags_cleared(struct page *page)
-{
- return !(page->flags & PAGE_FLAGS_CHECK_AT_PREP);
-}
-
-/*
- * __is_movable_balloon_page - helper to perform @page mapping->flags tests
- */
-static inline bool __is_movable_balloon_page(struct page *page)
-{
- struct address_space *mapping = page->mapping;
- return !PageAnon(page) && mapping_balloon(mapping);
-}
-
-/*
- * balloon_page_movable - test page->mapping->flags to identify balloon pages
- * that can be moved by compaction/migration.
- *
- * This function is used at core compaction's page isolation scheme, therefore
- * most pages exposed to it are not enlisted as balloon pages and so, to avoid
- * undesired side effects like racing against __free_pages(), we cannot afford
- * holding the page locked while testing page->mapping->flags here.
- *
- * As we might return false positives in the case of a balloon page being just
- * released under us, the page->mapping->flags need to be re-tested later,
- * under the proper page lock, at the functions that will be coping with the
- * balloon page case.
- */
-static inline bool balloon_page_movable(struct page *page)
-{
- /*
- * Before dereferencing and testing mapping->flags, let's make sure
- * this is not a page that uses ->mapping in a different way
- */
- if (page_flags_cleared(page) && !page_mapped(page) &&
- page_count(page) == 1)
- return __is_movable_balloon_page(page);
-
- return false;
-}
-
-/*
- * isolated_balloon_page - identify an isolated balloon page on private
- * compaction/migration page lists.
- *
- * After a compaction thread isolates a balloon page for migration, it raises
- * the page refcount to prevent concurrent compaction threads from re-isolating
- * the same page. For that reason putback_movable_pages(), or other routines
- * that need to identify isolated balloon pages on private pagelists, cannot
- * rely on balloon_page_movable() to accomplish the task.
- */
-static inline bool isolated_balloon_page(struct page *page)
-{
- /* Already isolated balloon pages, by default, have a raised refcount */
- if (page_flags_cleared(page) && !page_mapped(page) &&
- page_count(page) >= 2)
- return __is_movable_balloon_page(page);
-
- return false;
-}
-
-/*
* balloon_page_insert - insert a page into the balloon's page list and make
* the page->mapping assignment accordingly.
* @page : page to be assigned as a 'balloon page'
@@ -192,6 +121,7 @@ static inline void balloon_page_insert(struct page *page,
struct address_space *mapping,
struct list_head *head)
{
+ __SetPageBalloon(page);
page->mapping = mapping;
list_add(&page->lru, head);
}
@@ -206,6 +136,7 @@ static inline void balloon_page_insert(struct page *page,
*/
static inline void balloon_page_delete(struct page *page)
{
+ __ClearPageBalloon(page);
page->mapping = NULL;
list_del(&page->lru);
}
@@ -250,24 +181,16 @@ static inline void balloon_page_insert(struct page *page,
struct address_space *mapping,
struct list_head *head)
{
+ __SetPageBalloon(page);
list_add(&page->lru, head);
}
static inline void balloon_page_delete(struct page *page)
{
+ __ClearPageBalloon(page);
list_del(&page->lru);
}
-static inline bool balloon_page_movable(struct page *page)
-{
- return false;
-}
-
-static inline bool isolated_balloon_page(struct page *page)
-{
- return false;
-}
-
static inline bool balloon_page_isolate(struct page *page)
{
return false;
diff --git a/mm/Kconfig b/mm/Kconfig
index 72e0db0..e09cf0a 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -237,7 +237,7 @@ config MEMORY_BALLOON
config BALLOON_COMPACTION
bool "Allow for balloon memory compaction/migration"
def_bool y
- depends on COMPACTION && VIRTIO_BALLOON
+ depends on COMPACTION && MEMORY_BALLOON
help
Memory fragmentation introduced by ballooning might reduce
significantly the number of 2MB contiguous memory blocks that can be
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index 533c567..22c8e03 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -253,8 +253,7 @@ bool balloon_page_isolate(struct page *page)
* Prevent concurrent compaction threads from isolating
* an already isolated balloon page by refcount check.
*/
- if (__is_movable_balloon_page(page) &&
- page_count(page) == 2) {
+ if (PageBalloon(page) && page_count(page) == 2) {
__isolate_balloon_page(page);
unlock_page(page);
return true;
@@ -275,7 +274,7 @@ void balloon_page_putback(struct page *page)
*/
lock_page(page);
- if (__is_movable_balloon_page(page)) {
+ if (PageBalloon(page)) {
__putback_balloon_page(page);
/* drop the extra ref count taken for page isolation */
put_page(page);
@@ -300,7 +299,7 @@ int balloon_page_migrate(struct page *newpage,
*/
BUG_ON(!trylock_page(newpage));
- if (WARN_ON(!__is_movable_balloon_page(page))) {
+ if (WARN_ON(!PageBalloon(page))) {
dump_page(page, "not movable balloon page");
unlock_page(newpage);
return rc;
diff --git a/mm/compaction.c b/mm/compaction.c
index 0653f5f..e9aeed2 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -596,11 +596,10 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
* Skip any other type of page
*/
if (!PageLRU(page)) {
- if (unlikely(balloon_page_movable(page))) {
- if (balloon_page_isolate(page)) {
- /* Successfully isolated */
- goto isolate_success;
- }
+ if (unlikely(PageBalloon(page)) &&
+ balloon_page_isolate(page)) {
+ /* Successfully isolated */
+ goto isolate_success;
}
continue;
}
diff --git a/mm/migrate.c b/mm/migrate.c
index 161d044..c35e6f2 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -92,7 +92,7 @@ void putback_movable_pages(struct list_head *l)
list_del(&page->lru);
dec_zone_page_state(page, NR_ISOLATED_ANON +
page_is_file_cache(page));
- if (unlikely(isolated_balloon_page(page)))
+ if (unlikely(PageBalloon(page)))
balloon_page_putback(page);
else
putback_lru_page(page);
@@ -873,7 +873,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
}
}
- if (unlikely(__is_movable_balloon_page(page))) {
+ if (unlikely(PageBalloon(page))) {
/*
* A ballooned page does not need any special attention from
* physical to virtual reverse mapping procedures.
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2836b53..f90f93e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1160,7 +1160,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
list_for_each_entry_safe(page, next, page_list, lru) {
if (page_is_file_cache(page) && !PageDirty(page) &&
- !isolated_balloon_page(page)) {
+ !PageBalloon(page)) {
ClearPageActive(page);
list_move(&page->lru, &clean_pages);
}
--
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