Re: [PATCH v3 16/19] KVM: MMU: lockless walking shadow page table

[Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>]

On 07/07/2011 02:08 AM, Marcelo Tosatti wrote:

>> +static void free_pages_rcu(struct rcu_head *head)
>> +{
>> +	struct kvm_mmu_page *next, *sp;
>> +
>> +	sp = container_of(head, struct kvm_mmu_page, rcu);
>> +	while (sp) {
>> +		if (!list_empty(&sp->link))
>> +			next = list_first_entry(&sp->link,
>> +				      struct kvm_mmu_page, link);
>> +		else
>> +			next = NULL;
>> +		kvm_mmu_free_page(sp);
>> +		sp = next;
>> +	}
>> +}
> 
> There is no need for this while loop.
> 

The while loop is needed, since many shadow pages can be freed together in
the rcu context, on commit_zap_page path, we only remove the list head, and
the shadow page is still listed.