[...]
> 6. return last_page
>
> > + /* Remaining pages store in alloc.cache */
> > + list_for_each_entry_safe(page, next, &page_list, lru) {
> > + list_del(&page->lru);
> > + if ((pp_flags & PP_FLAG_DMA_MAP) &&
> > + unlikely(!page_pool_dma_map(pool, page))) {
> > + put_page(page);
> > + continue;
> > + }
>
> So if you added a last_page pointer what you could do is check for it
> here and assign it to the alloc cache. If last_page is not set the
> block would be skipped.
>
> > + if (likely(pool->alloc.count < PP_ALLOC_CACHE_SIZE)) {
> > + pool->alloc.cache[pool->alloc.count++] = page;
> > + pool->pages_state_hold_cnt++;
> > + trace_page_pool_state_hold(pool, page,
> > + pool->pages_state_hold_cnt);
> > + } else {
> > + put_page(page);
>
> If you are just calling put_page here aren't you leaking DMA mappings?
> Wouldn't you need to potentially unmap the page before you call
> put_page on it?
Oops, I completely missed that. Alexander is right here.
>
> > + }
> > + }
> > +out:
> > if ((pp_flags & PP_FLAG_DMA_MAP) &&
> > - unlikely(!page_pool_dma_map(pool, page))) {
> > - put_page(page);
> > + unlikely(!page_pool_dma_map(pool, first_page))) {
> > + put_page(first_page);
>
> I would probably move this block up and make it a part of the pp_order
> block above. Also since you are doing this in 2 spots it might make
> sense to look at possibly making this an inline function.
>
> > return NULL;
> > }
> >
> > /* Track how many pages are held 'in-flight' */
> > pool->pages_state_hold_cnt++;
> > - trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
> > + trace_page_pool_state_hold(pool, first_page, pool->pages_state_hold_cnt);
> >
> > /* When page just alloc'ed is should/must have refcnt 1. */
> > - return page;
> > + return first_page;
> > }
> >
> > /* For using page_pool replace: alloc_pages() API calls, but provide
> > --
> > 2.26.2
> >
Cheers
/Ilias
