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

On Tue, May 29, 2018 at 10:03:38AM -0700, Davidlohr Bueso wrote:

On Mon, 28 May 2018, Herbert Xu wrote:

quoted

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.

It doesn't explain it at all.  In fact I don't see why we neeed
three attempts, just do the GFP_NOFAIL as the second and final step.

Thanks,
-- 
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
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