[PATCH v3 19/21] memcg: check lru vectors emptiness in pre-destroy

[Konstantin Khlebnikov]

We must abort cgroup destroying if it still not empty,
resource counter cannot catch isolated uncharged pages.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
---
 mm/memcontrol.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4de8044..fbeff85 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4859,8 +4859,16 @@ free_out:
 static int mem_cgroup_pre_destroy(struct cgroup *cont)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	int ret;
+
+	ret = mem_cgroup_force_empty(memcg, false);
+	if (ret)
+		return ret;
 
-	return mem_cgroup_force_empty(memcg, false);
+	if (mem_cgroup_nr_lru_pages(memcg, -1))
+		return -EBUSY;
+
+	return 0;
 }
 
 static void mem_cgroup_destroy(struct cgroup *cont)

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