memcg: remove PCG_FILE_MAPPED

With the new lock scheme for updating memcg's page stat, we don't need a
flag PCG_FILE_MAPPED which was duplicated information of page_mapped().

[hughd@google.com: cosmetic fix]
[hughd@google.com: add comment to MEM_CGROUP_CHARGE_TYPE_MAPPED case in __mem_cgroup_uncharge_common()]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Greg Thelen <gthelen@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
index 7a3af74..a88cdba 100644 (file)
--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -6,8 +6,6 @@ enum {
        PCG_LOCK,  /* Lock for pc->mem_cgroup and following bits. */
        PCG_USED, /* this object is in use. */
        PCG_MIGRATION, /* under page migration */
-       /* flags for mem_cgroup and file and I/O status */
-       PCG_FILE_MAPPED, /* page is accounted as "mapped" */
        __NR_PCG_FLAGS,
 };
 
@@ -66,10 +64,6 @@ TESTPCGFLAG(Used, USED)
 CLEARPCGFLAG(Used, USED)
 SETPCGFLAG(Used, USED)
 
-SETPCGFLAG(FileMapped, FILE_MAPPED)
-CLEARPCGFLAG(FileMapped, FILE_MAPPED)
-TESTPCGFLAG(FileMapped, FILE_MAPPED)
-
 SETPCGFLAG(Migration, MIGRATION)
 CLEARPCGFLAG(Migration, MIGRATION)
 TESTPCGFLAG(Migration, MIGRATION)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index df1e180..0e13b2a 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1966,10 +1966,6 @@ void mem_cgroup_update_page_stat(struct page *page,
 
        switch (idx) {
        case MEMCG_NR_FILE_MAPPED:
-               if (val > 0)
-                       SetPageCgroupFileMapped(pc);
-               else if (!page_mapped(page))
-                       ClearPageCgroupFileMapped(pc);
                idx = MEM_CGROUP_STAT_FILE_MAPPED;
                break;
        default:
@@ -2617,7 +2613,7 @@ static int mem_cgroup_move_account(struct page *page,
 
        move_lock_mem_cgroup(from, &flags);
 
-       if (PageCgroupFileMapped(pc)) {
+       if (!anon && page_mapped(page)) {
                /* Update mapped_file data for mem_cgroup */
                preempt_disable();
                __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
@@ -2982,6 +2978,11 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
 
        switch (ctype) {
        case MEM_CGROUP_CHARGE_TYPE_MAPPED:
+               /*
+                * Generally PageAnon tells if it's the anon statistics to be
+                * updated; but sometimes e.g. mem_cgroup_uncharge_page() is
+                * used before page reached the stage of being marked PageAnon.
+                */
                anon = true;
                /* fallthrough */
        case MEM_CGROUP_CHARGE_TYPE_DROP: