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authorVladimir Davydov <vdavydov@parallels.com>2015-02-13 01:59:38 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-13 05:54:10 +0300
commit2788cf0c401c268b4819c5407493a8769b7007aa (patch)
tree863ea244d6908bd6e8149e6cd81270389a9426a8 /mm/memcontrol.c
parent3f97b163207c67a3b35931494ad3db1de66356f0 (diff)
downloadlinux-2788cf0c401c268b4819c5407493a8769b7007aa.tar.xz
memcg: reparent list_lrus and free kmemcg_id on css offline
Now, the only reason to keep kmemcg_id till css free is list_lru, which uses it to distribute elements between per-memcg lists. However, it can be easily sorted out - we only need to change kmemcg_id of an offline cgroup to its parent's id, making further list_lru_add()'s add elements to the parent's list, and then move all elements from the offline cgroup's list to the one of its parent. It will work, because a racing list_lru_del() does not need to know the list it is deleting the element from. It can decrement the wrong nr_items counter though, but the ongoing reparenting will fix it. After list_lru reparenting is done we are free to release kmemcg_id saving a valuable slot in a per-memcg array for new cgroups. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.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.c39
1 files changed, 34 insertions, 5 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index abfe0135bfdc..419c06b1794a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -334,6 +334,7 @@ struct mem_cgroup {
#if defined(CONFIG_MEMCG_KMEM)
/* Index in the kmem_cache->memcg_params.memcg_caches array */
int kmemcg_id;
+ bool kmem_acct_activated;
bool kmem_acct_active;
#endif
@@ -582,14 +583,10 @@ void memcg_put_cache_ids(void)
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->kmemcg_id >= 0) {
+ if (memcg->kmem_acct_activated)
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
@@ -3322,6 +3319,7 @@ static int memcg_activate_kmem(struct mem_cgroup *memcg,
int memcg_id;
BUG_ON(memcg->kmemcg_id >= 0);
+ BUG_ON(memcg->kmem_acct_activated);
BUG_ON(memcg->kmem_acct_active);
/*
@@ -3365,6 +3363,7 @@ static int memcg_activate_kmem(struct mem_cgroup *memcg,
* patched.
*/
memcg->kmemcg_id = memcg_id;
+ memcg->kmem_acct_activated = true;
memcg->kmem_acct_active = true;
out:
return err;
@@ -4047,6 +4046,10 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
static void memcg_deactivate_kmem(struct mem_cgroup *memcg)
{
+ struct cgroup_subsys_state *css;
+ struct mem_cgroup *parent, *child;
+ int kmemcg_id;
+
if (!memcg->kmem_acct_active)
return;
@@ -4059,6 +4062,32 @@ static void memcg_deactivate_kmem(struct mem_cgroup *memcg)
memcg->kmem_acct_active = false;
memcg_deactivate_kmem_caches(memcg);
+
+ kmemcg_id = memcg->kmemcg_id;
+ BUG_ON(kmemcg_id < 0);
+
+ parent = parent_mem_cgroup(memcg);
+ if (!parent)
+ parent = root_mem_cgroup;
+
+ /*
+ * 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
+ * memcg_drain_all_list_lrus().
+ */
+ 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;
+ if (!memcg->use_hierarchy)
+ break;
+ }
+ memcg_drain_all_list_lrus(kmemcg_id, parent->kmemcg_id);
+
+ memcg_free_cache_id(kmemcg_id);
}
static void memcg_destroy_kmem(struct mem_cgroup *memcg)