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>
This commit is contained in:
KAMEZAWA Hiroyuki 2008-10-18 20:28:09 -07:00 committed by Linus Torvalds
parent 073e587ec2
commit b7abea9630
3 changed files with 9 additions and 3 deletions

View File

@ -116,12 +116,12 @@ void __remove_from_page_cache(struct page *page)
{
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

View File

@ -734,6 +734,7 @@ void mem_cgroup_uncharge_page(struct page *page)
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);
}

View File

@ -330,8 +330,6 @@ static int migrate_page_move_mapping(struct address_space *mapping,
__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 int migrate_page_move_mapping(struct address_space *mapping,
*/
static void migrate_page_copy(struct page *newpage, struct page *page)
{
int anon;
copy_highpage(newpage, page);
if (PageError(page))
@ -378,8 +378,13 @@ static void migrate_page_copy(struct page *newpage, struct page *page)
#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.