Received-SPF: pass (google.com: domain of linux-kernel+bounces-206315-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Date: Fri, 7 Jun 2024 11:52:47 -0300
From: Jason Gunthorpe <jgg@ziepe.ca>
To: David Ahern <dsahern@kernel.org>
Cc: Pavel Begunkov <asml.silence@gmail.com>,
	Mina Almasry <almasrymina@google.com>,
	Christoph Hellwig <hch@infradead.org>, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-alpha@vger.kernel.org, linux-mips@vger.kernel.org,
	linux-parisc@vger.kernel.org, sparclinux@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Donald Hunter <donald.hunter@gmail.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Richard Henderson <richard.henderson@linaro.org>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	Matt Turner <mattst88@gmail.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	Helge Deller <deller@gmx.de>, Andreas Larsson <andreas@gaisler.com>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	Ilias Apalodimas <ilias.apalodimas@linaro.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Arnd Bergmann <arnd@arndb.de>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>, Stanislav Fomichev <sdf@google.com>,
	Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
	Steffen Klassert <steffen.klassert@secunet.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
	Shuah Khan <shuah@kernel.org>,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Christian =?utf-8?B?S8O2bmln?= <christian.koenig@amd.com>,
	David Wei <dw@davidwei.uk>, Yunsheng Lin <linyunsheng@huawei.com>,
	Shailend Chand <shailend@google.com>,
	Harshitha Ramamurthy <hramamurthy@google.com>,
	Shakeel Butt <shakeel.butt@linux.dev>,
	Jeroen de Borst <jeroendb@google.com>,
	Praveen Kaligineedi <pkaligineedi@google.com>
Subject: Re: [PATCH net-next v10 02/14] net: page_pool: create hooks for
 custom page providers
Message-ID: <20240607145247.GG791043@ziepe.ca>
References: <20240530201616.1316526-1-almasrymina@google.com>
 <20240530201616.1316526-3-almasrymina@google.com>
 <ZlqzER_ufrhlB28v@infradead.org>
 <CAHS8izMU_nMEr04J9kXiX6rJqK4nQKA+W-enKLhNxvK7=H2pgA@mail.gmail.com>
 <5aee4bba-ca65-443c-bd78-e5599b814a13@gmail.com>
 <CAHS8izNmT_NzgCu1pY1RKgJh+kP2rCL_90Gqau2Pkd3-48Q1_w@mail.gmail.com>
 <eb237e6e-3626-4435-8af5-11ed3931b0ac@gmail.com>
 <be2d140f-db0f-4d15-967c-972ea6586b5c@kernel.org>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <be2d140f-db0f-4d15-967c-972ea6586b5c@kernel.org>

On Fri, Jun 07, 2024 at 08:27:29AM -0600, David Ahern wrote:
> On 6/7/24 7:42 AM, Pavel Begunkov wrote:
> > I haven't seen any arguments against from the (net) maintainers so
> > far. Nor I see any objection against callbacks from them (considering
> > that either option adds an if).
> 
> I have said before I do not understand why the dmabuf paradigm is not
> sufficient for both device memory and host memory. A less than ideal
> control path to put hostmem in a dmabuf wrapper vs extra checks and
> changes in the datapath. The former should always be preferred.

I think Pavel explained this - his project is principally to replace
the lifetime policy of pages in the data plane. He wants to change
when a page is considered available for re-allocation because
userspace may continue to use the page after the netstack thinks it is
done with it. It sounds like having a different source of the pages is
the less important part.

IMHO it seems to compose poorly if you can only use the io_uring
lifecycle model with io_uring registered memory, and not with DMABUF
memory registered through Mina's mechanism.

Jason