Re: [PATCH 2/6] lib/rhashtable: guarantee initial hashtable allocation

On Mon, 28 May 2018, Herbert Xu wrote:

quoted

+	/*
+	 * This is api initialization and thus we need to guarantee the
+	 * initial rhashtable allocation. Upon failure, retry with a
+	 * smallest possible size, otherwise we exhaust our options with
+	 * __GFP_NOFAIL.
+	 */
 	tbl = bucket_table_alloc(ht, size, GFP_KERNEL);
-	if (tbl == NULL)
-		return -ENOMEM;
+	if (unlikely(tbl == NULL)) {
+		size = HASH_MIN_SIZE;
+
+		tbl = bucket_table_alloc(ht, size, GFP_KERNEL);
+		if (tbl == NULL)
+			tbl = bucket_table_alloc_retry(ht, size, GFP_KERNEL);
+	}

Perhaps you should also explain here why we don't just try the
minimum size with __GFP_NOFAIL as the second step rather than the
third.

Please see the comment above, I try to explain the rationale.

Thanks,
Davidlohr