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

[Davidlohr Bueso]

On Mon, 28 May 2018, Herbert Xu wrote:

> On Thu, May 24, 2018 at 02:11:31PM -0700, Davidlohr Bueso 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;
>
> You should also take min_size into account.  Yes I know the current
> code ignores it unless you also set nelem_hint.  But that's just a
> bug.

For the sake of simplicity, Linus suggested directly using HASH_MIN_SIZE
such that we have a single fallback.

Thanks,
Davidlohr