netdev - Re: [PATCH net v2] xdp: update mem type when page pool is used for generic XDP

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Message-ID: <20251001082737.23f5037f@kernel.org>
Date: Wed, 1 Oct 2025 08:27:37 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Cc: Octavian Purdila <tavip@...gle.com>, <davem@...emloft.net>,
 <edumazet@...gle.com>, <pabeni@...hat.com>, <horms@...nel.org>,
 <ast@...nel.org>, <daniel@...earbox.net>, <hawk@...nel.org>,
 <john.fastabend@...il.com>, <sdf@...ichev.me>, <kuniyu@...gle.com>,
 <aleksander.lobakin@...el.com>, <toke@...hat.com>, <lorenzo@...nel.org>,
 <netdev@...r.kernel.org>, <bpf@...r.kernel.org>,
 <syzbot+ff145014d6b0ce64a173@...kaller.appspotmail.com>
Subject: Re: [PATCH net v2] xdp: update mem type when page pool is used for
 generic XDP

On Wed, 1 Oct 2025 16:42:29 +0200 Maciej Fijalkowski wrote:
> Here we piggy back on sk_buff::pp_recycle setting as it implies underlying
> memory is backed by page pool.

skb->pp_recycle means that if the pages of the skb came from a pp then
the skb is holding a pp reference not a full page reference on those
pages. It does not mean that all pages of an skb came from pp.
In practice it may be equivalent, especially here. But I'm slightly
worried that checking pp_recycle will lead to confusion..