Re: [RFC 2/6] mm, mempolicy: stop adjusting current->il_next in mpol_rebind_nodemask()

Vlastimil Babka
2017-04-12T21:18:59Z

On 12.4.2017 23:16, Christoph Lameter wrote:
> On Wed, 12 Apr 2017, Vlastimil Babka wrote:
>
>>>> Well, interleave_nodes() will then potentially return a node outside of
>>>> the allowed memory policy when its called for the first time after
>>>> mpol_rebind_.. . But thenn it will find the next node within the
>>>> nodemask and work correctly for the next invocations.
>>>
>>> Hmm, you're right. But that could be easily fixed if il_next became il_prev, so
>>> we would return the result of next_node_in(il_prev) and also store it as the new
>>> il_prev, right? I somehow assumed it already worked that way.
>
> Yup that makes sense and I thought about that when I saw the problem too.
>
>> @@ -863,6 +856,18 @@ static int lookup_node(unsigned long addr)
>> return err;
>> }
>>
>> +/* Do dynamic interleaving for a process */
>> +static unsigned interleave_nodes(struct mempolicy *policy, bool update_prev)
>
> Why do you need an additional flag? Would it not be better to always
> update and switch the update_prev=false case to simply use
> next_node_in()?

Looked to me as better wrapping, but probably overengineered, ok. Will change
for v2.