cgroup: fix incorrect destination cgroup in cgroup_update_dfl_csses()

cgroup_update_dfl_csses() should move each task in the subtree to
self; however, it was incorrectly calling cgroup_migrate_add_src()
with the root of the subtree as @dst_cgrp.  Fortunately,
cgroup_migrate_add_src() currently uses @dst_cgrp only to determine
the hierarchy and the bug doesn't cause any actual breakages.  Fix it.

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c63fce0c5b2419795196863a8a22fa592d4713eb..50879aadcbd0e2c6dcabe9ae64c73dc67ac7405a 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2901,7 +2901,7 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp)
                struct cgrp_cset_link *link;
 
                list_for_each_entry(link, &dsct->cset_links, cset_link)
-                       cgroup_migrate_add_src(link->cset, cgrp,
+                       cgroup_migrate_add_src(link->cset, dsct,
                                               &preloaded_csets);
        }
        spin_unlock_bh(&css_set_lock);