hugetlb/cgroup: remove exclude and wakeup rmdir calls from migrate

We already hold the hugetlb_lock.  That should prevent a parallel cgroup
rmdir from touching page's hugetlb cgroup.  So remove the exclude and
wakeup calls.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb_cgroup.c

@@ -385,6 +385,10 @@ int __init hugetlb_cgroup_file_init(int idx)
 	return 0;
 }
 
+/*
+ * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
+ * when we migrate hugepages
+ */
 void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
 {
 	struct hugetlb_cgroup *h_cg;
@@ -397,13 +401,11 @@ void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
 	spin_lock(&hugetlb_lock);
 	h_cg = hugetlb_cgroup_from_page(oldhpage);
 	set_hugetlb_cgroup(oldhpage, NULL);
-	cgroup_exclude_rmdir(&h_cg->css);
 
 	/* move the h_cg details to new cgroup */
 	set_hugetlb_cgroup(newhpage, h_cg);
 	list_move(&newhpage->lru, &h->hugepage_activelist);
 	spin_unlock(&hugetlb_lock);
-	cgroup_release_and_wakeup_rmdir(&h_cg->css);
 	return;
 }