Re: [PATCH net-next v2 4/5] net: remove skb->pp_recycle and consolidate netmem refcounting

[sashiko-bot@kernel.org]

> skb->pp_recycle was introduced in commit 6a5bcd84e886 ("page_pool: Allow
> drivers to hint on SKB recycling") when drivers had to explicitly opt in
> to page_pool SKB recycling and to avoid touching struct page on the free
> path. Today every page_pool-backed netmem carries its own identity via
> netmem_is_pp(), making the per-SKB skb->pp_recycle bitfield redundant
> and error-prone when SKBs are cloned, split, segmented, shifted, or
> coalesced across page_pool and non-page_pool buffers. For non-page_pool
> pages, get_page(), put_page(), and skb_free_frag() immediately load the
> same first struct page cache line (compound_head, which shares the cache
> line with pp_magic), so checking netmem_is_pp() does not add an extra
> cache-line load.
> 
> Remove skb->pp_recycle and check netmem_is_pp() directly via
> napi_pp_get_page() and napi_pp_put_page() inside netmem_inc_ref(),
> netmem_dec_ref(), and skb_pp_recycle(), dropping the now-redundant
> [ ... ]
>   skb_irq_freeable() does not exclude SKBs holding page_pool memory
>   before calling __kfree_skb() with hardirqs disabled; TX SKBs carrying
>   spliced page_pool fragments are subject to the same path.
> 
> Signed-off-by: Mina Almasry <almasrymina@google.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261108060016.2131509-1-almasrymina@google.com?part=4