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

From: Kamezawa Hiroyuki
Date: Thu Jun 21 2012 - 20:07:03 EST


(2012/06/22 5:13), Andrew Morton wrote:
On Thu, 21 Jun 2012 17:17:01 +0900
Kamezawa Hiroyuki<kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:

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.


For some reason I'm having trouble applying these patches - many
rejects, need to massage it in by hand.


Oh, sorry. Is it space breakage or some ? (I had mailer troubles in the last week..)
Or, maybe, my tree/patch queue was too old.
I'll rebased to new -mm tree when I post new patch.

--- 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)

Let's document the return value. The mem_cgroup_force_empty_list()
comment is a mess so I tried to help it a bit. How does this look?

--- a/mm/memcontrol.c~memcg-make-mem_cgroup_force_empty_list-return-bool-fix
+++ a/mm/memcontrol.c
@@ -3609,8 +3609,10 @@ unsigned long mem_cgroup_soft_limit_recl
}

/*
- * 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 bool mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
int node, int zid, enum lru_list lru)
_

Seems nice! Thank you very much.

Regards,
-Kame



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