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([2a01:4b00:bd21:4f00:7cc6:d3ca:494:116c]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429eb403849sm4648357f8f.1.2025.11.06.03.07.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 Nov 2025 03:08:00 -0800 (PST) Message-ID: <785c9d27-23e7-4ecf-ad2e-202ba506f2e0@gmail.com> Date: Thu, 6 Nov 2025 11:07:58 +0000 Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC mm v5 1/2] page_pool: check nmdesc->pp to see its usage as page pool for net_iov not page-backed To: Byungchul Park , linux-mm@kvack.org, netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel_team@skhynix.com, harry.yoo@oracle.com, ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, kuba@kernel.org, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, tariqt@nvidia.com, mbloch@nvidia.com, andrew+netdev@lunn.ch, edumazet@google.com, pabeni@redhat.com, akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, horms@kernel.org, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, ilias.apalodimas@linaro.org, willy@infradead.org, brauner@kernel.org, kas@kernel.org, yuzhao@google.com, usamaarif642@gmail.com, baolin.wang@linux.alibaba.com, almasrymina@google.com, toke@redhat.com, bpf@vger.kernel.org, linux-rdma@vger.kernel.org, sfr@canb.auug.org.au, dw@davidwei.uk, ap420073@gmail.com, dtatulea@nvidia.com References: <20251103075108.26437-1-byungchul@sk.com> <20251103075108.26437-2-byungchul@sk.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20251103075108.26437-2-byungchul@sk.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/3/25 07:51, Byungchul Park wrote: > Currently, the condition 'page->pp_magic == PP_SIGNATURE' is used to > determine if a page belongs to a page pool. However, with the planned > removal of ->pp_magic, we will instead leverage the page_type in struct > page, such as PGTY_netpp, for this purpose. > > That works for page-backed network memory. However, for net_iov not > page-backed, the identification cannot be based on the page_type. > Instead, nmdesc->pp can be used to see if it belongs to a page pool, by > making sure nmdesc->pp is NULL otherwise. > > For net_iov not page-backed, initialize it using nmdesc->pp = NULL in > net_devmem_bind_dmabuf() and using kvmalloc_array(__GFP_ZERO) in > io_zcrx_create_area() so that netmem_is_pp() can check if nmdesc->pp is > !NULL to confirm its usage as page pool. Reviewed-by: Pavel Begunkov -- Pavel Begunkov