Messages in this thread Patch in this message | | | Date | Mon, 28 May 2018 17:49:56 +0800 | From | Herbert Xu <> | Subject | Re: [PATCH 2/6] lib/rhashtable: guarantee initial hashtable allocation |
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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)
> @@ -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 <herbert@gondor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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