Re: [PATCH v2] mm, page_pool: introduce a new page type for page pool in page type

[Pavel Begunkov]

On 7/29/25 02:04, Byungchul Park wrote:
> On Mon, Jul 28, 2025 at 07:49:30PM +0100, Pavel Begunkov wrote:
> > On 7/28/25 19:39, Mina Almasry wrote:
> > > On Mon, Jul 28, 2025 at 11:35 AM Pavel Begunkov <asml.silence@xxxxxxxxx> wrote:

...>>> This may be my bad since I said we should check if it's 0 initialized.
> > > It looks like on the devmem side as well we kvmalloc_array the niovs,
> > > and if I'm checking through the helpers right, kvmalloc_array does
> > > 0-initialize indeed.
> >
> > I wouldn't rely on that, it's just for zcrx I do:
> >
> > kvmalloc_array(...,  GFP_KERNEL | __GFP_ZERO);
>
> For net_devmem_bind_dmabuf(), __GFP_ZERO will add bigger overhead than
> just assignment, 'niov->pp = NULL'.

That's not a place where you should care about zeroing overhead.

> I'd like to ask you if you are still good with __GFP_ZERO overhead
> before going ahead.

However, it might be easier for you to just assign it directly
for devmem and let Mina add GFP_ZERO if he fancy the idea.

--
Pavel Begunkov