[PATCH] mm: use get_oder() and check size is is_power_of_2

[Barry Song <v-songbaohua@xxxxxxxx>]

Using get_order() is more robust according to Baolin.
It is also better to filter illegal size such as 3KB,
16KB according to David.

Suggested-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
---
 mm/huge_memory.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 01beda16aece..d6dade8ac5f6 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -952,14 +952,17 @@ static inline int get_order_from_str(const char *size_str)
 	int order;
 
 	size = memparse(size_str, &endptr);
-	order = fls(size >> PAGE_SHIFT) - 1;
-	if ((1 << order) & ~THP_ORDERS_ALL_ANON) {
-		pr_err("invalid size %s(order %d) in thp_anon boot parameter\n",
-			size_str, order);
-		return -EINVAL;
-	}
+
+	if (!is_power_of_2(size >> PAGE_SHIFT))
+		goto err;
+	order = get_order(size);
+	if ((1 << order) & ~THP_ORDERS_ALL_ANON)
+		goto err;
 
 	return order;
+err:
+	pr_err("invalid size %s in thp_anon boot parameter\n", size_str);
+	return -EINVAL;
 }
 
 static char str_dup[PAGE_SIZE] __meminitdata;
-- 
2.34.1

Thanks
Barry