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

[Douglas Freimuth <freimuth@linux.ibm.com>]

On 4/30/26 11:31 AM, Claudio Imbrenda wrote:
> On Wed, 29 Apr 2026 10:44:51 -0400
> Matthew Rosato <mjrosato@linux.ibm.com> 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.