[PATCH -mmotm 1/3] memcg: add mem_cgroup_cancel_charge()

Daisuke Nishimura
2009-11-11T01:43:47Z

There are some places calling both res_counter_uncharge() and css_put()
to cancel the charge and the refcnt we have got by mem_cgroup_tyr_charge().

This patch introduces mem_cgroup_cancel_charge() and call it in those places.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
---
mm/memcontrol.c | 38 ++++++++++++++++++--------------------
1 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4bd3451..d92c398 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1500,6 +1500,21 @@ nomem:
}

/*
+ * Somemtimes we have to undo a charge we got by try_charge().
+ * This function is for that and do uncharge, put css's refcnt.
+ * gotten by try_charge().
+ */
+static void mem_cgroup_cancel_charge(struct mem_cgroup *mem)
+{
+ if (!mem_cgroup_is_root(mem)) {
+ res_counter_uncharge(&mem->res, PAGE_SIZE);
+ if (do_swap_account)
+ res_counter_uncharge(&mem->memsw, PAGE_SIZE);
+ }
+ css_put(&mem->css);
+}
+
+/*
* A helper function to get mem_cgroup from ID. must be called under
* rcu_read_lock(). The caller must check css_is_removed() or some if
* it's concern. (dropping refcnt from swap can be called against removed
@@ -1565,12 +1580,7 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
lock_page_cgroup(pc);
if (unlikely(PageCgroupUsed(pc))) {
unlock_page_cgroup(pc);
- if (!mem_cgroup_is_root(mem)) {
- res_counter_uncharge(&mem->res, PAGE_SIZE);
- if (do_swap_account)
- res_counter_uncharge(&mem->memsw, PAGE_SIZE);
- }
- css_put(&mem->css);
+ mem_cgroup_cancel_charge(mem);
return;
}

@@ -1734,14 +1744,7 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc,
cancel:
put_page(page);
uncharge:
- /* drop extra refcnt by try_charge() */
- css_put(&parent->css);
- /* uncharge if move fails */
- if (!mem_cgroup_is_root(parent)) {
- res_counter_uncharge(&parent->res, PAGE_SIZE);
- if (do_swap_account)
- res_counter_uncharge(&parent->memsw, PAGE_SIZE);
- }
+ mem_cgroup_cancel_charge(parent);
return ret;
}

@@ -1957,12 +1960,7 @@ void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
return;
if (!mem)
return;
- if (!mem_cgroup_is_root(mem)) {
- res_counter_uncharge(&mem->res, PAGE_SIZE);
- if (do_swap_account)
- res_counter_uncharge(&mem->memsw, PAGE_SIZE);
- }
- css_put(&mem->css);
+ mem_cgroup_cancel_charge(mem);
}

static void
--
1.5.6.1