The patch titled
memcg-get-put-parents-at-create-free fix
has been added to the -mm tree. Its filename is
memcg-get-put-parents-at-create-free-fix.patch
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------------------------------------------------------
Subject: memcg-get-put-parents-at-create-free fix
From: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Andrew suggested that it's strange to add a little helper function for get(),
while put() is open-code.
This patch also adds a few comments.
Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Reviewed-by; KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Paul Menage <menage@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff -puN mm/memcontrol.c~memcg-get-put-parents-at-create-free-fix mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-get-put-parents-at-create-free-fix
+++ a/mm/memcontrol.c
@@ -203,7 +203,6 @@ pcg_default_flags[NR_CHARGE_TYPE] = {
static void mem_cgroup_get(struct mem_cgroup *mem);
static void mem_cgroup_put(struct mem_cgroup *mem);
static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
-static void mem_cgroup_get_parent(struct mem_cgroup *mem);
static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
struct page_cgroup *pc,
@@ -2203,6 +2202,9 @@ static void mem_cgroup_put(struct mem_cg
}
}
+/*
+ * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
+ */
static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem)
{
if (!mem->res.parent)
@@ -2210,14 +2212,6 @@ static struct mem_cgroup *parent_mem_cgr
return mem_cgroup_from_res_counter(mem->res.parent, res);
}
-static void mem_cgroup_get_parent(struct mem_cgroup *mem)
-{
- struct mem_cgroup *parent = parent_mem_cgroup(mem);
-
- if (parent)
- mem_cgroup_get(parent);
-}
-
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
static void __init enable_swap_cgroup(void)
{
@@ -2255,6 +2249,13 @@ mem_cgroup_create(struct cgroup_subsys *
if (parent && parent->use_hierarchy) {
res_counter_init(&mem->res, &parent->res);
res_counter_init(&mem->memsw, &parent->memsw);
+ /*
+ * We increment refcnt of the parent to ensure that we can
+ * safely access it on res_counter_charge/uncharge.
+ * This refcnt will be decremented when freeing this
+ * mem_cgroup(see mem_cgroup_put).
+ */
+ mem_cgroup_get(parent);
} else {
res_counter_init(&mem->res, NULL);
res_counter_init(&mem->memsw, NULL);
@@ -2265,7 +2266,6 @@ mem_cgroup_create(struct cgroup_subsys *
if (parent)
mem->swappiness = get_swappiness(parent);
atomic_set(&mem->refcnt, 1);
- mem_cgroup_get_parent(mem);
return &mem->css;
free_out:
__mem_cgroup_free(mem);
_
Patches currently in -mm which might be from nishimura@xxxxxxxxxxxxxxxxx are
origin.patch
memcg-get-put-parents-at-create-free.patch
memcg-get-put-parents-at-create-free-fix.patch
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