On Tue, Feb 28, 2012 at 10:22 PM, KAMEZAWA Hiroyuki
[off-list ref] wrote:

On Mon, 27 Feb 2012 14:58:45 -0800
Suleiman Souhlal [off-list ref] wrote:

quoted

A later patch will also use this to move the accounting to the root
cgroup.

Signed-off-by: Suleiman Souhlal <redacted>
---
 mm/memcontrol.c |   30 +++++++++++++++++++++++++++++-
 1 files changed, 29 insertions(+), 1 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 11e31d6..6f44fcb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c

@@ -378,6 +378,7 @@ static void mem_cgroup_get(struct mem_cgroup *memcg);

 static void mem_cgroup_put(struct mem_cgroup *memcg);
 static void memcg_kmem_init(struct mem_cgroup *memcg,
     struct mem_cgroup *parent);
+static void memcg_kmem_move(struct mem_cgroup *memcg);

 /* Writing them here to avoid exposing memcg's inner layout */
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM

@@ -3674,6 +3675,7 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool free_all)

      int ret;
      int node, zid, shrink;
      int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+     unsigned long usage;
      struct cgroup *cgrp = memcg->css.cgroup;

      css_get(&memcg->css);

@@ -3693,6 +3695,8 @@ move_account:

              /* This is for making all *used* pages to be on LRU. */
              lru_add_drain_all();
              drain_all_stock_sync(memcg);
+             if (!free_all)
+                     memcg_kmem_move(memcg);
              ret = 0;
              mem_cgroup_start_move(memcg);
              for_each_node_state(node, N_HIGH_MEMORY) {

@@ -3714,8 +3718,13 @@ move_account:

              if (ret == -ENOMEM)
                      goto try_to_free;
              cond_resched();
+             usage = memcg->res.usage;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+             if (free_all && !memcg->independent_kmem_limit)
+                     usage -= memcg->kmem_bytes.usage;
+#endif

Why we need this even if memcg_kmem_move() does uncharge ?

We need it when manually calling force_empty.

-- Suleiman