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authorMuchun Song <songmuchun@bytedance.com>2021-11-05 23:37:53 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-11-06 23:30:35 +0300
commit642688681133a501d149349ba1a824204f3540e1 (patch)
tree76e6ddbc4d7bc20f84c0c26679208694963ed858 /mm/memcontrol.c
parent41d17431df4aa7c57761e04f81c94fb3c3beedf4 (diff)
downloadlinux-642688681133a501d149349ba1a824204f3540e1.tar.xz
mm: memcontrol: remove kmemcg_id reparenting
Since slab objects and kmem pages are charged to object cgroup instead of memory cgroup, memcg_reparent_objcgs() will reparent this cgroup and all its descendants to its parent cgroup. This already makes further list_lru_add()'s add elements to the parent's list. So it is unnecessary to change kmemcg_id of an offline cgroup to its parent's id. It just wastes CPU cycles. Just remove the redundant code. Link: https://lkml.kernel.org/r/20211025125102.56533-1-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Roman Gushchin <guro@fb.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
-rw-r--r--mm/memcontrol.c19
1 files changed, 4 insertions, 15 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e4fcb6e55f75..1e2d3f378edd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3650,8 +3650,7 @@ static int memcg_online_kmem(struct mem_cgroup *memcg)
static void memcg_offline_kmem(struct mem_cgroup *memcg)
{
- struct cgroup_subsys_state *css;
- struct mem_cgroup *parent, *child;
+ struct mem_cgroup *parent;
int kmemcg_id;
if (memcg->kmem_state != KMEM_ONLINE)
@@ -3669,21 +3668,11 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg)
BUG_ON(kmemcg_id < 0);
/*
- * Change kmemcg_id of this cgroup and all its descendants to the
- * parent's id, and then move all entries from this cgroup's list_lrus
- * to ones of the parent. After we have finished, all list_lrus
- * corresponding to this cgroup are guaranteed to remain empty. The
- * ordering is imposed by list_lru_node->lock taken by
+ * After we have finished memcg_reparent_objcgs(), all list_lrus
+ * corresponding to this cgroup are guaranteed to remain empty.
+ * The ordering is imposed by list_lru_node->lock taken by
* memcg_drain_all_list_lrus().
*/
- rcu_read_lock(); /* can be called from css_free w/o cgroup_mutex */
- css_for_each_descendant_pre(css, &memcg->css) {
- child = mem_cgroup_from_css(css);
- BUG_ON(child->kmemcg_id != kmemcg_id);
- child->kmemcg_id = parent->kmemcg_id;
- }
- rcu_read_unlock();
-
memcg_drain_all_list_lrus(kmemcg_id, parent);
memcg_free_cache_id(kmemcg_id);