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authorVladimir Davydov <vdavydov@parallels.com>2015-02-12 14:59:38 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-12 18:54:10 -0800
commit2788cf0c401c268b4819c5407493a8769b7007aa (patch)
tree863ea244d6908bd6e8149e6cd81270389a9426a8 /include/linux/list_lru.h
parent3f97b163207c67a3b35931494ad3db1de66356f0 (diff)
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 'include/linux/list_lru.h')
-rw-r--r--include/linux/list_lru.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
index 7edf9c9ab9eb..2a6b9947aaa3 100644
--- a/include/linux/list_lru.h
+++ b/include/linux/list_lru.h
@@ -26,7 +26,7 @@ enum lru_status {
struct list_lru_one {
struct list_head list;
- /* kept as signed so we can catch imbalance bugs */
+ /* may become negative during memcg reparenting */
long nr_items;
};
@@ -62,6 +62,7 @@ int __list_lru_init(struct list_lru *lru, bool memcg_aware,
#define list_lru_init_memcg(lru) __list_lru_init((lru), true, NULL)
int memcg_update_all_list_lrus(int num_memcgs);
+void memcg_drain_all_list_lrus(int src_idx, int dst_idx);
/**
* list_lru_add: add an element to the lru list's tail