Re: [PATCH 15/16] rcu/tree: Allocate a page when caller is preemptible

[Joel Fernandes]

On Wed, Nov 04, 2020 at 12:39:31PM +0100, Uladzislau Rezki wrote:
[..] 
> > > -	if (!krcp->bkvhead[idx] ||
> > > -			krcp->bkvhead[idx]->nr_records == KVFREE_BULK_MAX_ENTR) {
> > > -		bnode = get_cached_bnode(krcp);
> > > -		/* Switch to emergency path. */
> > > +	if (!(*krcp)->bkvhead[idx] ||
> > > +			(*krcp)->bkvhead[idx]->nr_records == KVFREE_BULK_MAX_ENTR) {
> > > +		bnode = get_cached_bnode(*krcp);
> > > +		if (!bnode && can_alloc_page) {
> > 
> > I think you can directly put preemptible() here with a comment saying
> > allocate only if preemptible and get rid of can_alloc_page.
> > 
> Not really. We check preemtable() before acquiring the internal lock,
> otherwise it will always return "false". Thus, it is checked on the
> entry in the beginning.

You are right. Sorry. Sounds good to me.

 - Joel