Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:
 "More MM work: a memcg scalability improvememt"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm/lru: revise the comments of lru_lock
  mm/lru: introduce relock_page_lruvec()
  mm/lru: replace pgdat lru_lock with lruvec lock
  mm/swap.c: serialize memcg changes in pagevec_lru_move_fn
  mm/compaction: do page isolation first in compaction
  mm/lru: introduce TestClearPageLRU()
  mm/mlock: remove __munlock_isolate_lru_page()
  mm/mlock: remove lru_lock on TestClearPageMlocked
  mm/vmscan: remove lruvec reget in move_pages_to_lru
  mm/lru: move lock into lru_note_cost
  mm/swap.c: fold vm event PGROTATED into pagevec_move_tail_fn
  mm/memcg: add debug checking in lock_page_memcg
  mm: page_idle_get_page() does not need lru_lock
  mm/rmap: stop store reordering issue on page->mapping
  mm/vmscan: remove unnecessary lruvec adding
  mm/thp: narrow lru locking
  mm/thp: simplify lru_add_page_tail()
  mm/thp: use head for head page in lru_add_page_tail()
  mm/thp: move lru_add_page_tail() to huge_memory.c

2 files changed, 12 insertions, 24 deletions

diff --git a/Documentation/admin-guide/cgroup-v1/memcg_test.rst b/Documentation/admin-guide/cgroup-v1/memcg_test.rst
index 4f83de2dab6e..45b94f7b3beb 100644
--- a/Documentation/admin-guide/cgroup-v1/memcg_test.rst
+++ b/Documentation/admin-guide/cgroup-v1/memcg_test.rst
@@ -133,18 +133,9 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
 
 8. LRU
 ======
-        Each memcg has its own private LRU. Now, its handling is under global
-	VM's control (means that it's handled under global pgdat->lru_lock).
-	Almost all routines around memcg's LRU is called by global LRU's
-	list management functions under pgdat->lru_lock.
-
-	A special function is mem_cgroup_isolate_pages(). This scans
-	memcg's private LRU and call __isolate_lru_page() to extract a page
-	from LRU.
-
-	(By __isolate_lru_page(), the page is removed from both of global and
-	private LRU.)
-
+	Each memcg has its own vector of LRUs (inactive anon, active anon,
+	inactive file, active file, unevictable) of pages from each node,
+	each LRU handled under a single lru_lock for that memcg and node.
 
 9. Typical Tests.
 =================
diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst
index a44cd467d218..52688ae34461 100644
--- a/Documentation/admin-guide/cgroup-v1/memory.rst
+++ b/Documentation/admin-guide/cgroup-v1/memory.rst
@@ -287,20 +287,17 @@ When oom event notifier is registered, event will be delivered.
 2.6 Locking
 -----------
 
-   lock_page_cgroup()/unlock_page_cgroup() should not be called under
-   the i_pages lock.
+Lock order is as follows:
 
-   Other lock order is following:
+  Page lock (PG_locked bit of page->flags)
+    mm->page_table_lock or split pte_lock
+      lock_page_memcg (memcg->move_lock)
+        mapping->i_pages lock
+          lruvec->lru_lock.
 
-   PG_locked.
-     mm->page_table_lock
-         pgdat->lru_lock
-	   lock_page_cgroup.
-
-  In many cases, just lock_page_cgroup() is called.
-
-  per-zone-per-cgroup LRU (cgroup's private LRU) is just guarded by
-  pgdat->lru_lock, it has no lock of its own.
+Per-node-per-memcgroup LRU (cgroup's private LRU) is guarded by
+lruvec->lru_lock; PG_lru bit of page->flags is cleared before
+isolating a page from its LRU under lruvec->lru_lock.
 
 2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM)
 -----------------------------------------------