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authorTejun Heo <tj@kernel.org>2017-07-23 08:18:26 -0400
committerTejun Heo <tj@kernel.org>2017-07-25 13:15:29 -0400
commit918a8c2c4ea4fab8b7855b8da48bbaf0a733ebb0 (patch)
tree55b740ec2319dc2a358e86a6b0323a6a71786a5c /Documentation/cgroup-v2.txt
parent7a0cf0e74ab6cfd8e561f5f12860d4ff8844905a (diff)
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cgroup: remove unnecessary empty check when enabling threaded mode
cgroup_enable_threaded() checks that the cgroup doesn't have any tasks or children and fails the operation if so. This test is unnecessary because the first part is already checked by cgroup_can_be_thread_root() and the latter is unnecessary. The latter actually cause a behavioral oddity. Please consider the following hierarchy. All cgroups are domains. A / \ B C \ D If B is made threaded, C and D becomes invalid domains. Due to the no children restriction, threaded mode can't be enabled on C. For C and D, the only thing the user can do is removal. There is no reason for this restriction. Remove it. Acked-by: Waiman Long <longman@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'Documentation/cgroup-v2.txt')
-rw-r--r--Documentation/cgroup-v2.txt5
1 files changed, 3 insertions, 2 deletions
diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt
index cb9ea281ab72..dec5afdaa36d 100644
--- a/Documentation/cgroup-v2.txt
+++ b/Documentation/cgroup-v2.txt
@@ -274,8 +274,9 @@ thread mode, the following conditions must be met.
- As the cgroup will join the parent's resource domain. The parent
must either be a valid (threaded) domain or a threaded cgroup.
-- The cgroup must be empty. No enabled controllers, child cgroups or
- processes.
+- When the parent is an unthreaded domain, it must not have any domain
+ controllers enabled or populated domain children. The root is
+ exempt from this requirement.
Topology-wise, a cgroup can be in an invalid state. Please consider
the following toplogy::