Re: [PATCH 2/6] lib/rhashtable: guarantee initial hashtable allocation
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: 2018-05-28 09:50:28
Also in:
lkml
On Thu, May 24, 2018 at 02:11:31PM -0700, Davidlohr Bueso wrote:
-static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
- size_t nbuckets,
- gfp_t gfp)
+static struct bucket_table *__bucket_table_alloc(struct rhashtable *ht,
+ size_t nbuckets,
+ gfp_t gfp, bool retry)
{
struct bucket_table *tbl = NULL;
size_t size, max_locks;
int i;
size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]);
+ if (retry) {
+ gfp |= __GFP_NOFAIL;
+ tbl = kzalloc(size, gfp);
+ } /* fall-through */I'd prefer this logic to be moved to the caller. So just call the function with GFP_KERNEL | __GFP_NOFAIL. Of course you need to modify bucket_table_alloc so that it still treats this as GFP_KERNEL (as opposed to GFP_ATOMIC). That is, instead of
if (gfp != GFP_KERNEL)
You will need if ((gfp & ~__GFP_NOFAIL) != GFP_KERNEL)
quoted hunk ↗ jump to hunk
@@ -1067,9 +1086,20 @@ int rhashtable_init(struct rhashtable *ht, } } + /* + * 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. Cheers, -- Email: Herbert Xu [off-list ref] Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt