memcg: make mem_cgroup_force_empty_list() return bool
mem_cgroup_force_empty_list() just returns 0 or -EBUSY and -EBUSY
indicates 'you need to retry'. Make mem_cgroup_force_empty_list() return
a bool to simplify the logic.
[akpm@linux-foundation.org: rework mem_cgroup_force_empty_list()'s comment]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9647866..a2677e0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3609,10 +3609,12 @@
}
/*
- * This routine traverse page_cgroup in given list and drop them all.
- * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
+ * Traverse a specified page_cgroup list and try to drop them all. This doesn't
+ * reclaim the pages page themselves - it just removes the page_cgroups.
+ * Returns true if some page_cgroups were not freed, indicating that the caller
+ * must retry this operation.
*/
-static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
+static bool mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
int node, int zid, enum lru_list lru)
{
struct mem_cgroup_per_zone *mz;
@@ -3620,7 +3622,6 @@
struct list_head *list;
struct page *busy;
struct zone *zone;
- int ret = 0;
zone = &NODE_DATA(node)->node_zones[zid];
mz = mem_cgroup_zoneinfo(memcg, node, zid);
@@ -3634,7 +3635,6 @@
struct page_cgroup *pc;
struct page *page;
- ret = 0;
spin_lock_irqsave(&zone->lru_lock, flags);
if (list_empty(list)) {
spin_unlock_irqrestore(&zone->lru_lock, flags);
@@ -3651,19 +3651,14 @@
pc = lookup_page_cgroup(page);
- ret = mem_cgroup_move_parent(page, pc, memcg);
-
- if (ret == -EBUSY || ret == -EINVAL) {
+ if (mem_cgroup_move_parent(page, pc, memcg)) {
/* found lock contention or "pc" is obsolete. */
busy = page;
cond_resched();
} else
busy = NULL;
}
-
- if (!ret && !list_empty(list))
- return -EBUSY;
- return ret;
+ return !list_empty(list);
}
/*