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

From: Davidlohr Bueso
Date: Tue May 29 2018 - 13:20:34 EST


On Mon, 28 May 2018, Herbert Xu wrote:
+ /*
+ * 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