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-rw-r--r--mm/memcontrol.c57
1 files changed, 50 insertions, 7 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b9afa060b8d6..9a62ac3ea881 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -346,6 +346,7 @@ struct mem_cgroup {
/* internal only representation about the status of kmem accounting. */
enum {
KMEM_ACCOUNTED_ACTIVE = 0, /* accounted by this cgroup itself */
+ KMEM_ACCOUNTED_DEAD, /* dead memcg with pending kmem charges */
};
#define KMEM_ACCOUNTED_MASK (1 << KMEM_ACCOUNTED_ACTIVE)
@@ -355,6 +356,23 @@ static inline void memcg_kmem_set_active(struct mem_cgroup *memcg)
{
set_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags);
}
+
+static bool memcg_kmem_is_active(struct mem_cgroup *memcg)
+{
+ return test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags);
+}
+
+static void memcg_kmem_mark_dead(struct mem_cgroup *memcg)
+{
+ if (test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags))
+ set_bit(KMEM_ACCOUNTED_DEAD, &memcg->kmem_account_flags);
+}
+
+static bool memcg_kmem_test_and_clear_dead(struct mem_cgroup *memcg)
+{
+ return test_and_clear_bit(KMEM_ACCOUNTED_DEAD,
+ &memcg->kmem_account_flags);
+}
#endif
/* Stuffs for move charges at task migration. */
@@ -2722,10 +2740,16 @@ static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size)
{
- res_counter_uncharge(&memcg->kmem, size);
res_counter_uncharge(&memcg->res, size);
if (do_swap_account)
res_counter_uncharge(&memcg->memsw, size);
+
+ /* Not down to 0 */
+ if (res_counter_uncharge(&memcg->kmem, size))
+ return;
+
+ if (memcg_kmem_test_and_clear_dead(memcg))
+ mem_cgroup_put(memcg);
}
/*
@@ -2764,13 +2788,9 @@ __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order)
return true;
}
- mem_cgroup_get(memcg);
-
ret = memcg_charge_kmem(memcg, gfp, PAGE_SIZE << order);
if (!ret)
*_memcg = memcg;
- else
- mem_cgroup_put(memcg);
css_put(&memcg->css);
return (ret == 0);
@@ -2786,7 +2806,6 @@ void __memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg,
/* The page allocation failed. Revert */
if (!page) {
memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
- mem_cgroup_put(memcg);
return;
}
@@ -2827,7 +2846,6 @@ void __memcg_kmem_uncharge_pages(struct page *page, int order)
VM_BUG_ON(mem_cgroup_is_root(memcg));
memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
- mem_cgroup_put(memcg);
}
#endif /* CONFIG_MEMCG_KMEM */
@@ -4217,6 +4235,13 @@ static int memcg_update_kmem_limit(struct cgroup *cont, u64 val)
VM_BUG_ON(ret);
memcg_kmem_set_active(memcg);
+ /*
+ * kmem charges can outlive the cgroup. In the case of slab
+ * pages, for instance, a page contain objects from various
+ * processes, so it is unfeasible to migrate them away. We
+ * need to reference count the memcg because of that.
+ */
+ mem_cgroup_get(memcg);
} else
ret = res_counter_set_limit(&memcg->kmem, val);
out:
@@ -4232,6 +4257,10 @@ static void memcg_propagate_kmem(struct mem_cgroup *memcg)
if (!parent)
return;
memcg->kmem_account_flags = parent->kmem_account_flags;
+#ifdef CONFIG_MEMCG_KMEM
+ if (memcg_kmem_is_active(memcg))
+ mem_cgroup_get(memcg);
+#endif
}
/*
@@ -4920,6 +4949,20 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
static void kmem_cgroup_destroy(struct mem_cgroup *memcg)
{
mem_cgroup_sockets_destroy(memcg);
+
+ memcg_kmem_mark_dead(memcg);
+
+ if (res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0)
+ return;
+
+ /*
+ * Charges already down to 0, undo mem_cgroup_get() done in the charge
+ * path here, being careful not to race with memcg_uncharge_kmem: it is
+ * possible that the charges went down to 0 between mark_dead and the
+ * res_counter read, so in that case, we don't need the put
+ */
+ if (memcg_kmem_test_and_clear_dead(memcg))
+ mem_cgroup_put(memcg);
}
#else
static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)