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SubjectRe: [PATCH net-next] net: skbuff: update comment about pfmemalloc propagating
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On 5/15/23 06:01, Yunsheng Lin wrote:
> __skb_fill_page_desc_noacc() is not doing any pfmemalloc
> propagating, and yet it has a comment about that, commit
> 84ce071e38a6 ("net: introduce __skb_fill_page_desc_noacc")
> may have accidentally moved it to __skb_fill_page_desc_noacc(),
> so move it back to __skb_fill_page_desc() which is supposed
> to be doing pfmemalloc propagating.

Looks good,

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>


> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
> CC: Pavel Begunkov <asml.silence@gmail.com>
> ---
> Also maybe we need a better name for 'noacc' or add some
> comment about that, as 'noacc' seems a little confusing
> for __skb_fill_page_desc_noacc().

It's a known pattern bur in block/ and should be "noacct",
but yeah, it can be more specific.

> ---
> include/linux/skbuff.h | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 00e8c435fa1a..4b8d55247198 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2426,11 +2426,6 @@ static inline void __skb_fill_page_desc_noacc(struct skb_shared_info *shinfo,
> {
> skb_frag_t *frag = &shinfo->frags[i];
>
> - /*
> - * Propagate page pfmemalloc to the skb if we can. The problem is
> - * that not all callers have unique ownership of the page but rely
> - * on page_is_pfmemalloc doing the right thing(tm).
> - */
> skb_frag_fill_page_desc(frag, page, off, size);
> }
>
> @@ -2463,6 +2458,11 @@ static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
> struct page *page, int off, int size)
> {
> __skb_fill_page_desc_noacc(skb_shinfo(skb), i, page, off, size);
> +
> + /* Propagate page pfmemalloc to the skb if we can. The problem is
> + * that not all callers have unique ownership of the page but rely
> + * on page_is_pfmemalloc doing the right thing(tm).
> + */
> page = compound_head(page);
> if (page_is_pfmemalloc(page))
> skb->pfmemalloc = true;

--
Pavel Begunkov

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