From 62716ea0f2ea4253984008fd4a96a532674ac58f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 23 Feb 2016 10:00:51 -0500 Subject: [PATCH] cgroup: use ->subtree_control when testing no internal process rule No internal process rule is enforced by cgroup_migrate_prepare_dst() during process migration. It tests whether the target cgroup's ->child_subsys_mask is zero which is different from "subtree_control" write path which tests ->subtree_control. This hasn't mattered because up until now, both ->child_subsys_mask and ->subtree_control are zero or non-zero at the same time. However, with the planned addition of implicit controllers, this will no longer be true. This patch prepares for the change by making cgorup_migrate_prepare_dst() test ->subtree_control instead. Signed-off-by: Tejun Heo --- kernel/cgroup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 2b114368666c..ac5451e7c458 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2527,11 +2527,11 @@ static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, lockdep_assert_held(&cgroup_mutex); /* - * Except for the root, subtree_ss_mask must be zero for a cgroup + * Except for the root, subtree_control must be zero for a cgroup * with tasks so that child cgroups don't compete against tasks. */ if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) && - dst_cgrp->subtree_ss_mask) + dst_cgrp->subtree_control) return -EBUSY; /* look up the dst cset for each src cset and link it to src */