Re: [PATCH net-next v4 2/5] page_frag: unify gfp bits for order 3 page allocation

[Paolo Abeni]

On Fri, 2024-02-02 at 10:10 +0800, Yunsheng Lin wrote:
> On 2024/2/1 21:16, Paolo Abeni wrote:
> 
> > from the __page_frag_cache_refill() allocator - which never accesses
> > the memory reserves.
> 
> I am not really sure I understand the above commemt.
> The semantic is the same as skb_page_frag_refill() as explained above
> as my understanding. Note that __page_frag_cache_refill() use 'gfp_mask'
> for allocating order 3 pages and use the original 'gfp' for allocating
> order 0 pages.

You are right! I got fooled misreading 'gfp' as 'gfp_mask' in there.

> > I'm unsure we want to propagate the __page_frag_cache_refill behavior
> > here, the current behavior could be required by some systems.
> > 
> > It looks like this series still leave the skb_page_frag_refill()
> > allocator alone, what about dropping this chunk, too? 
> 
> As explained above, I would prefer to keep it as it is as it seems
> to be quite obvious that we can avoid possible pressure for mm by
> not using memory reserve for order 3 pages as we have the fallback
> for order 0 pages.
> 
> Please let me know if there is anything obvious I missed.
> 

I still think/fear that behaviours changes here could have
subtle/negative side effects - even if I agree the change looks safe.

I think the series without this patch would still achieve its goals and
would be much more uncontroversial. What about move this patch as a
standalone follow-up?

Thanks!

Paolo