Thread (20 messages) 20 messages, 4 authors, 2012-03-01

Re: [PATCH next] memcg: remove PCG_CACHE page_cgroup flag fix

From: KAMEZAWA Hiroyuki <hidden>
Date: 2012-02-29 05:56:00
Also in: lkml

On Tue, 28 Feb 2012 21:30:17 -0800 (PST)
Hugh Dickins [off-list ref] wrote:
Swapping tmpfs loads show absurd wrapped rss and wrong cache in memcg's
memory.stat statistics: __mem_cgroup_uncharge_common() is failing to
distinguish the anon and tmpfs cases.
I thought I tested this..maybe my test was wrong, sorry.

Mostly we can decide between them by PageAnon, which is reliable once
it has been set; but there are several callers who need to uncharge a
MEM_CGROUP_CHARGE_TYPE_MAPPED page before it was fully initialized,
so allow that case to override the PageAnon decision.

Signed-off-by: Hugh Dickins <hughd@google.com>
---
Acked-by: KAMEZAWA Hiroyuki <redacted>

It seems I should revisit these and consinder some cleanup...

_OFF TOPIC_
To be honest, I don't like to have anon/rss counter in memory.stat because
we have LRU statistics. It seems enough.. If shmem counter is required,
I think we should have shmem counter rather than anon/rss.

quoted hunk ↗ jump to hunk
 mm/memcontrol.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
--- 3.3-rc5-next/mm/memcontrol.c	2012-02-25 10:06:52.496035568 -0800
+++ linux/mm/memcontrol.c	2012-02-26 10:44:32.146365398 -0800
@@ -2944,13 +2944,16 @@ __mem_cgroup_uncharge_common(struct page
 	if (!PageCgroupUsed(pc))
 		goto unlock_out;
 
+	anon = PageAnon(page);
+
 	switch (ctype) {
 	case MEM_CGROUP_CHARGE_TYPE_MAPPED:
+		anon = true;
+		/* fallthrough */
 	case MEM_CGROUP_CHARGE_TYPE_DROP:
 		/* See mem_cgroup_prepare_migration() */
 		if (page_mapped(page) || PageCgroupMigration(pc))
 			goto unlock_out;
-		anon = true;
 		break;
 	case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
 		if (!PageAnon(page)) {	/* Shared memory */
@@ -2958,10 +2961,8 @@ __mem_cgroup_uncharge_common(struct page
 				goto unlock_out;
 		} else if (page_mapped(page)) /* Anon */
 				goto unlock_out;
-		anon = true;
 		break;
 	default:
-		anon = false;
 		break;
 	}
 
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