Re: [PATCH 2/2] memcg: clean up force_empty_list() return value check

[Kamezawa Hiroyuki]

You're right and I think this will be much cleaner.
==

From 9b6224616282d74838b393485eb7c9215f546ec9 Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Date: Thu, 21 Jun 2012 17:28:55 +0900
Subject: [PATCH 2/2] memcg: make mem_cgroup_force_empty_list() as boolean function

Now, mem_cgroup_force_empty_list() just returns 0 or -EBUSY and
-EBUSY is just indicating 'you need to retry.'.
This patch makes mem_cgroup_force_empty_list() as boolean function and
make the logic simpler.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
 mm/memcontrol.c |   13 +++----------
 1 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 90a2ad4..767440c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3797,7 +3797,7 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
  * This routine traverse page_cgroup in given list and drop them all.
  * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
  */
-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;
@@ -3805,7 +3805,6 @@ static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
 	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);
@@ -3819,7 +3818,6 @@ static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
 		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);
@@ -3836,19 +3834,14 @@ static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
 
 		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 			/* found lock contention or "pc" is obsolete.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);
 }
 
 /*
--
1.7.4.1


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