path: root/mm/page-writeback.c
diff options
authorJohannes Weiner <>2021-04-29 22:55:32 -0700
committerLinus Torvalds <>2021-04-30 11:20:37 -0700
commit1c824a680b1b67ad43c0908f11a70bcf37af56d5 (patch)
tree4e732f16ab91e6bf8a0e31ac8417342f9fb693dc /mm/page-writeback.c
parent79e3094c53c56d0d4da23f578de271e7602ba5ed (diff)
mm: page-writeback: simplify memcg handling in test_clear_page_writeback()
Page writeback doesn't hold a page reference, which allows truncate to free a page the second PageWriteback is cleared. This used to require special attention in test_clear_page_writeback(), where we had to be careful not to rely on the unstable page->memcg binding and look up all the necessary information before clearing the writeback flag. Since commit 073861ed77b6 ("mm: fix VM_BUG_ON(PageTail) and BUG_ON(PageWriteback)") test_clear_page_writeback() is called with an explicit reference on the page, and this dance is no longer needed. Use unlock_page_memcg() and dec_lruvec_page_state() directly. This removes the last user of the lock_page_memcg() return value, change it to void. Touch up the comments in there as well. This also removes the last extern user of __unlock_page_memcg(), make it static. Further, it removes the last user of dec_lruvec_state(), delete it, along with a few other unused helpers. Link: Signed-off-by: Johannes Weiner <> Acked-by: Hugh Dickins <> Reviewed-by: Shakeel Butt <> Acked-by: Michal Hocko <> Cc: Roman Gushchin <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/page-writeback.c')
1 files changed, 3 insertions, 6 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 9e35b636a393..5e761fb62800 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2722,12 +2722,9 @@ EXPORT_SYMBOL(clear_page_dirty_for_io);
int test_clear_page_writeback(struct page *page)
struct address_space *mapping = page_mapping(page);
- struct mem_cgroup *memcg;
- struct lruvec *lruvec;
int ret;
- memcg = lock_page_memcg(page);
- lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
+ lock_page_memcg(page);
if (mapping && mapping_use_writeback_tags(mapping)) {
struct inode *inode = mapping->host;
struct backing_dev_info *bdi = inode_to_bdi(inode);
@@ -2755,11 +2752,11 @@ int test_clear_page_writeback(struct page *page)
ret = TestClearPageWriteback(page);
if (ret) {
- dec_lruvec_state(lruvec, NR_WRITEBACK);
+ dec_lruvec_page_state(page, NR_WRITEBACK);
dec_zone_page_state(page, NR_ZONE_WRITE_PENDING);
inc_node_page_state(page, NR_WRITTEN);
- __unlock_page_memcg(memcg);
+ unlock_page_memcg(page);
return ret;