memcg: make page->mapping NULL before uncharge
This patch tries to make page->mapping to be NULL before
mem_cgroup_uncharge_cache_page() is called.
"page->mapping == NULL" is a good check for "whether the page is still
radix-tree or not". This patch also adds BUG_ON() to
mem_cgroup_uncharge_cache_page();
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/filemap.c b/mm/filemap.c
index e1b23fd..ab85536 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -116,12 +116,12 @@
{
struct address_space *mapping = page->mapping;
- mem_cgroup_uncharge_cache_page(page);
radix_tree_delete(&mapping->page_tree, page->index);
page->mapping = NULL;
mapping->nrpages--;
__dec_zone_page_state(page, NR_FILE_PAGES);
BUG_ON(page_mapped(page));
+ mem_cgroup_uncharge_cache_page(page);
/*
* Some filesystems seem to re-dirty the page even after
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e93a4db..6f8b5b3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -734,6 +734,7 @@
void mem_cgroup_uncharge_cache_page(struct page *page)
{
VM_BUG_ON(page_mapped(page));
+ VM_BUG_ON(page->mapping);
__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
}
diff --git a/mm/migrate.c b/mm/migrate.c
index 11c6c56..6602941 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -330,8 +330,6 @@
__inc_zone_page_state(newpage, NR_FILE_PAGES);
spin_unlock_irq(&mapping->tree_lock);
- if (!PageSwapCache(newpage))
- mem_cgroup_uncharge_cache_page(page);
return 0;
}
@@ -341,6 +339,8 @@
*/
static void migrate_page_copy(struct page *newpage, struct page *page)
{
+ int anon;
+
copy_highpage(newpage, page);
if (PageError(page))
@@ -378,8 +378,13 @@
#endif
ClearPagePrivate(page);
set_page_private(page, 0);
+ /* page->mapping contains a flag for PageAnon() */
+ anon = PageAnon(page);
page->mapping = NULL;
+ if (!anon) /* This page was removed from radix-tree. */
+ mem_cgroup_uncharge_cache_page(page);
+
/*
* If any waiters have accumulated on the new page then
* wake them up.