mm, hugetlb: move the error handle logic out of normal code path

alloc_huge_page() now mixes normal code path with error handle logic.
This patches move out the error handle logic, to make normal code path
more clean and redue code duplicate.
Signed-off-by: NJianyu Zhan <nasa4836@gmail.com>
Acked-by: NDavidlohr Bueso <davidlohr@hp.com>
Reviewed-by: NMichal Hocko <mhocko@suse.cz>
Reviewed-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

@@ -1386,24 +1386,17 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
 			return ERR_PTR(-ENOSPC);
 
 	ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
-	if (ret) {
-		if (chg || avoid_reserve)
-			hugepage_subpool_put_pages(spool, 1);
-		return ERR_PTR(-ENOSPC);
-	}
+	if (ret)
+		goto out_subpool_put;
+
 	spin_lock(&hugetlb_lock);
 	page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, chg);
 	if (!page) {
 		spin_unlock(&hugetlb_lock);
 		page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
-		if (!page) {
-			hugetlb_cgroup_uncharge_cgroup(idx,
-						       pages_per_huge_page(h),
-						       h_cg);
-			if (chg || avoid_reserve)
-				hugepage_subpool_put_pages(spool, 1);
-			return ERR_PTR(-ENOSPC);
-		}
+		if (!page)
+			goto out_uncharge_cgroup;
+
 		spin_lock(&hugetlb_lock);
 		list_move(&page->lru, &h->hugepage_activelist);
 		/* Fall through */
@@ -1415,6 +1408,13 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
 
 	vma_commit_reservation(h, vma, addr);
 	return page;
+
+out_uncharge_cgroup:
+	hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
+out_subpool_put:
+	if (chg || avoid_reserve)
+		hugepage_subpool_put_pages(spool, 1);
+	return ERR_PTR(-ENOSPC);
 }
 
 /*