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b=OTC0a5Hfz2bIcz5D2HrfrJo58w+gy90avsEXUUw04oPPw6qE8a2sYWSllSYsLM3yLu rJuZBNhA+VZfu3v9Oncm3J487z8rm82q+28hy6HhqsKYWwWTyh+1a8F4Qjygt1sZY1WP fGRmeywLUU7WszCyGlBLpoIMSX+TmTPa0I+a0k/UCaF1N6BSwa132Ux1QRmZDBTJJLI7 usZC08m5a+7i6ouYNQRYcBrbcKYZeQcnSReRPk3QINQ808gbUDAvWl3TCq3viDFR7wjs VV0jTrsbpL/9KR0hFeNRCcZHj3LmqW3hErxaz5kCHAZltNr5XOaP4cBBO+/yPpt7jROa UN5w== X-Gm-Message-State: APuU4Z+D/2HwK1xugrzJFaTd7cSwu0pUi5fxfTDa9OLk5XNg8a5KkOGr 96XlPx43Zd9riCRnnPr+Q1u1A7vjnkVTXWwTN23Rqxcaw9ppvYxONaXTMENSR8wYlC+H3q0Xdxa /TLPsMPQeF81kNklxeb7PGTlszx2+fdCSjAq81M7LDxyMZ81vtVch12zHj5NPjMGcWqSocdBB3e GUek0kmcCpEv+5cFYJKNZJ6VG6NxrwqM/2ECtENWrfgwBvPSr3+eC2o13doUycoEA= X-Received: from dlar7.prod.google.com ([2002:a05:701b:21c7:b0:195:8b4e:20b7]) (user=almasrymina job=prod-delivery.src-stubby-dispatcher) by 2002:a05:701b:4517:10b0:185:fd0c:4585 with SMTP id a92af1059eb24-1ac5fb18de9mr20662974c88.33.1793740467189; Tue, 03 Nov 2026 13:14:27 -0800 (PST) Date: Tue, 3 Nov 2026 21:14:20 +0000 In-Reply-To: <20261103211424.127627-1-almasrymina@google.com> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 References: <20261103211424.127627-1-almasrymina@google.com> X-Mailer: git-send-email 2.56.0.385.gac671c819a-goog Message-ID: <20261103211424.127627-2-almasrymina@google.com> Subject: [PATCH net-next v1 1/5] net: skbuff: skip managed zerocopy frags in skb_frag_ref() From: Mina Almasry To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, linux-mm@kvack.org, bpf@vger.kernel.org, linux-wireless@vger.kernel.org, linux-doc@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, imx@lists.linux.dev, linux-rdma@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-omap@vger.kernel.org Cc: Mina Almasry , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Steffen Klassert , Herbert Xu , Willem de Bruijn , Stanislav Fomichev , Pavel Begunkov , Bobby Eshleman , Andrew Lunn , "Michael S. Tsirkin" , Jason Wang , "=?UTF-8?q?Eugenio=20P=C3=A9rez?=" , Xuan Zhuo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jesper Dangaard Brouer , Ilias Apalodimas , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Sabrina Dubroca , Johannes Berg , Byungchul Park , Jonathan Corbet , Shuah Khan , Randy Dunlap , Lorenzo Bianconi , Wen Gu , Philo Lu , Justin Chen , Florian Fainelli , Vikas Gupta , Michael Chan , Pavan Chebbi , Doug Berger , Nicolai Buchwitz , Satish Kharat , Wei Fang , Frank Li , Shenwei Wang , Joshua Washington , Harshitha Ramamurthy , Jijie Shao , Jian Shen , Fan Gong , Tony Nguyen , Przemek Kitszel , Marcin Wojtas , Russell King , Sunil Goutham , Geetha sowjanya , Ratheesh Kannoth , Subbaraya Sundeep , Bharat Bhushan , Felix Fietkau , Matthias Brugger , AngeloGioacchino Del Regno , Tariq Toukan , Saeed Mahameed , Mark Bloch , Leon Romanovsky , Ido Schimmel , Petr Machata , Horatiu Vultur , UNGLinuxDriver@microchip.com, Daniel Machon , Steen Hegelund , Haiyang Zhang , Wei Liu , Dexuan Cui , Yibo Dong , Brett Creeley , Justin Lai , Larry Chiu , "=?UTF-8?q?Niklas=20S=C3=B6derlund?=" , Paul Barker , Masahisa Kojima , Maxime Chevallier , Maxime Coquelin , Alexandre Torgue , FUJITA Tomonori , Siddharth Vadapalli , Roger Quadros , MD Danish Anwar , Jiawen Wu , Mengyuan Lou , Ronak Doshi , Ryder Lee , Shayne Chen , Sean Wang , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Jordan Rhee , Ankit Garg , Tim Hostetler , Erni Sri Satya Vennela , Eric Joyner , Mohammad Heib , Prabu Thayalan , Chintan Vankar , Nora Schiffer , Alexander Sverdlin , Kevin Hao , Karl Mehltretter , Aleksandr Loktionov , Meghana Malladi , Jacob Keller , StanleyYP Wang Content-Type: text/plain; charset="UTF-8" skb_frag_unref() and skb_release_data() skip releasing references on managed zerocopy fragments (SKBFL_MANAGED_FRAG_REFS), whereas skb_frag_ref() acquires a reference unconditionally. If skb_frag_ref() is called on a managed zerocopy SKB, the acquired reference is never released by skb_frag_unref() or skb_release_data(). Skip acquiring a reference in skb_frag_ref() when skb_zcopy_managed(skb) is true so skb_frag_ref() matches skb_frag_unref() and skb_release_data(), and disable share_ok in iptfs_output_queued() when skb_zcopy_managed(skb) is true so iptfs_consume_frags() does not append unreferenced fragments into a managed zerocopy outer SKB. Signed-off-by: Mina Almasry --- include/linux/skbuff_ref.h | 10 +++++++--- net/core/net_test.c | 10 ++++++++++ net/xfrm/xfrm_iptfs.c | 3 ++- 3 files changed, 19 insertions(+), 4 deletions(-) diff --git a/include/linux/skbuff_ref.h b/include/linux/skbuff_ref.h index b6f6da556ee90..e94c599ce83d2 100644 --- a/include/linux/skbuff_ref.h +++ b/include/linux/skbuff_ref.h @@ -36,12 +36,16 @@ static __always_inline void skb_netmem_ref(netmem_ref netmem, bool recycle) * * Acquires a reference on the @f'th fragment of @skb via skb_netmem_ref() * (pp_ref_count if skb->pp_recycle and page_pool-backed, else non-pp - * backing refcount). Counterpart to skb_frag_unref(). + * backing refcount), skipping managed zerocopy fragments. Counterpart to + * skb_frag_unref(). */ static __always_inline void skb_frag_ref(struct sk_buff *skb, int f) { - skb_netmem_ref(skb_frag_netmem(&skb_shinfo(skb)->frags[f]), - skb->pp_recycle); + struct skb_shared_info *shinfo = skb_shinfo(skb); + + if (!skb_zcopy_managed(skb)) + skb_netmem_ref(skb_frag_netmem(&shinfo->frags[f]), + skb->pp_recycle); } bool napi_pp_put_page(netmem_ref netmem); diff --git a/net/core/net_test.c b/net/core/net_test.c index 2b5080c226636..e20059a00003c 100644 --- a/net/core/net_test.c +++ b/net/core/net_test.c @@ -571,6 +571,16 @@ static void netmem_ref_test_page(struct kunit *test) skb_frag_unref(skb, 0); KUNIT_EXPECT_EQ(test, page_ref_count(page), base_ref); + /* SKBFL_MANAGED_FRAG_REFS skips both skb_frag_ref and skb_frag_unref */ + skb_shinfo(skb)->flags |= SKBFL_ZEROCOPY_ENABLE | + SKBFL_MANAGED_FRAG_REFS; + skb_frag_ref(skb, 0); + KUNIT_EXPECT_EQ(test, page_ref_count(page), base_ref); + skb_frag_unref(skb, 0); + KUNIT_EXPECT_EQ(test, page_ref_count(page), base_ref); + skb_shinfo(skb)->flags &= ~(SKBFL_ZEROCOPY_ENABLE | + SKBFL_MANAGED_FRAG_REFS); + skb_shinfo(skb)->nr_frags = 0; consume_skb(skb); __free_page(page); diff --git a/net/xfrm/xfrm_iptfs.c b/net/xfrm/xfrm_iptfs.c index 103cf7c5dbfb9..04ef833074fc8 100644 --- a/net/xfrm/xfrm_iptfs.c +++ b/net/xfrm/xfrm_iptfs.c @@ -2258,7 +2258,8 @@ static void iptfs_output_queued(struct xfrm_state *x, struct sk_buff_head *list) nextp = &(*nextp)->next; } - if (shi->frag_list || skb_cloned(skb) || skb_shared(skb)) + if (shi->frag_list || skb_cloned(skb) || skb_shared(skb) || + skb_zcopy_managed(skb)) share_ok = false; /* See if we have enough space to simply append. -- 2.56.0.385.gac671c819a-goog