[PATCH -mm 5/8] memcg: free kmem cache id on css offline

[Vladimir Davydov <vdavydov@parallels.com>]

This will allow new kmem active cgroups to reuse the id and therefore
the caches used by the dead memory cgroup.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
---
 mm/memcontrol.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 923fe4c29e92..755604079d8e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -605,14 +605,10 @@ int memcg_limited_groups_array_size;
 struct static_key memcg_kmem_enabled_key;
 EXPORT_SYMBOL(memcg_kmem_enabled_key);
 
-static void memcg_free_cache_id(int id);
-
 static void disarm_kmem_keys(struct mem_cgroup *memcg)
 {
-	if (memcg_kmem_is_active(memcg)) {
+	if (memcg_kmem_is_active(memcg))
 		static_key_slow_dec(&memcg_kmem_enabled_key);
-		memcg_free_cache_id(memcg->kmemcg_id);
-	}
 	/*
 	 * This check can't live in kmem destruction function,
 	 * since the charges will outlive the cgroup
@@ -4730,6 +4726,11 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
 	spin_unlock(&memcg->event_list_lock);
 
 	vmpressure_cleanup(&memcg->vmpressure);
+
+#ifdef CONFIG_MEMCG_KMEM
+	if (memcg_kmem_is_active(memcg))
+		memcg_free_cache_id(memcg_cache_id(memcg));
+#endif
 }
 
 static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
-- 
1.7.10.4

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