mm, hugetlb_cgroup: align hugetlb cgroup limit to hugepage size

Memcg aligns memory.limit_in_bytes to PAGE_SIZE as part of the resource
counter since it makes no sense to allow a partial page to be charged.

As a result of the hugetlb cgroup using the resource counter, it is also
aligned to PAGE_SIZE but makes no sense unless aligned to the size of
the hugepage being limited.

Align hugetlb cgroup limit to hugepage size.

Signed-off-by: David Rientjes <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: "Aneesh Kumar K.V" <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/hugetlb_cgroup.c

@@ -275,6 +275,7 @@ static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
 		ret = res_counter_memparse_write_strategy(buf, &val);
 		if (ret)
 			break;
+		val = ALIGN(val, 1ULL << huge_page_shift(&hstates[idx]));
 		ret = res_counter_set_limit(&h_cg->hugepage[idx], val);
 		break;
 	default: