Re: [PATCH v4 1/3] KVM: s390: Add map/unmap ioctl and clean mappings post-guest

[Douglas Freimuth]

On 4/30/26 11:31 AM, Claudio Imbrenda wrote:
> On Wed, 29 Apr 2026 10:44:51 -0400
> Matthew Rosato <mjrosato@xxxxxxxxxxxxx> wrote:
>
> [...]
>
> > > +		if (locked)
> > > +			mmap_read_unlock(mm);
> > > +		mmput(mm);
> > > +	}
> > > +
> > > +	return page;
> > > +}
> > > +
> > > +static int kvm_s390_adapter_map(struct kvm *kvm, unsigned int id, __u64 addr)
> > > +{
> > > +	struct s390_io_adapter *adapter = get_io_adapter(kvm, id);
> > > +	struct s390_map_info *map;
> > > +	unsigned long flags;
> > > +	__u64 host_addr;
> > > +	int ret, idx;
> > > +
> > > +	if (!adapter || !addr)
> > > +		return -EINVAL;
> > > +
> > > +	map = kzalloc_obj(*map, GFP_KERNEL_ACCOUNT);
> > > +	if (!map)
> > > +		return -ENOMEM;
> > > +
> > > +	INIT_LIST_HEAD(&map->list);
> > > +	idx = srcu_read_lock(&kvm->srcu);
> > > +	host_addr = gpa_to_hva(kvm, addr);
> > > +	if (kvm_is_error_hva(host_addr)) {
> > > +		srcu_read_unlock(&kvm->srcu, idx);
> > > +		kfree(map);
> >
> > Drop this kfree(), you already do this when you goto out
>
> have you considered using __free(kvfree) and let the compiler free map
> for you automatically? (or it doesn't work here?)
>
> [...]

Claudio good suggestion to consider, thank you. At this stage I will 
consider it for follow-on including looking at how you have used in 
other parts of the kernel. And will consider for new projects too.