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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Jan Kara , Andrew Morton , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Matthew Brost , Joshua Hahn , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Johannes Weiner , Song Liu , Rik van Riel , Miklos Szeredi , Alexander Viro , Christian Brauner , Hugh Dickins , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , Arnd Bergmann , Jason Gunthorpe , Kevin Tian , "Joerg Roedel (AMD)" , Robin Murphy , Steve Sistare , John Hubbard , "Jose A. Perez de Azpillaga" , Josef Bacik , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Neal Cardwell , Kuniyuki Iwashima Cc: "David Hildenbrand (Arm)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, fuse-devel@lists.linux.dev, linux-arch@vger.kernel.org, iommu@lists.linux.dev, netdev@vger.kernel.org, stable@vger.kernel.org, Pedro Falcato X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2437; i=david@kernel.org; h=from:subject:message-id; bh=2HIVuRJemzSar8UdUmReSo7kyB3JDSJ5ToRfjKbRBOI=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLK+OWf1PDr6KcJKb/52PYHbuw2PHj399hVnfKbJfLaef HXVC64WHaUsDGIcDLJiiixBwfcNXr5cV1vtxscMM4eVCWQIAxenAEzEJIrhD5eqTtHJ0jVXewXm m3DxrJ/HxcBz0OObysLvTItenzivx8XwT32S4UHWfZdm7bnYtaXSeO+j//xK9fN0b1deez8h1t7 gGwcA X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 2A8A280002 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Stat-Signature: g4w896m5fmao9yj81qz4maygz7fi6b63 X-Rspam-User: X-HE-Tag: 1794524158-263910 X-HE-Meta: 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 F4JrJwfH mm69p4+gWaJ8x+WoWww5EnKmuD07qJJxZyQzhYUEGN2Uvqs9TMcrdsWPjlcr97mYpdoPnY6xNE3TREBR0b83mAJaeyRqcdsfamlJHBFFNh0A8we3PlmwZUUnXqHqP7zzv40xT8kQHYDLTq+9UGvCmjN7Qi6mHMalLdeqpKFyNWdliBzt+Iv0K3srg8yofC01qGB904lAhsK6gtVN7hGtdU9eRyV9cGVjfuYEwwSwkofXwSnpngUGEncgteou22UzFxwrx7Y290VKZDKv20/BC2CVQdekV+OuQC0M2/D1/5RFeVH6MquQgdxJmla7cVZa4VmVN Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Various networking features use MSG_SPLICE_PAGES to add pages to skbs, whereby skb_append_pagefrags() takes a page reference for each fragment it adds. Pages spliced from pipes were already checked when entering the pipe, but in-kernel users like sunrpc pass pagecache pages directly. This allows for exceeding folio refcount limits. This is not specific to large pagecache folios, but with them it is a lot easier to reach the refcount limit, as page table mappings can cheaply create many references. Let's use try_get_page() in skb_append_pagefrags() and fail with -EFAULT. Don't use -EMSGSIZE, as TCP would just retry with a new skb. The only caller, skb_splice_from_iter(), handles that. Fixes: 800d8c63b2e9 ("shmem: add huge pages support") Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") Fixes: 793917d997df ("mm/readahead: Add large folio readahead") Cc: stable@vger.kernel.org Acked-by: Pedro Falcato Signed-off-by: David Hildenbrand (Arm) --- net/core/skbuff.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index f473c74956b8b..5e3f910eeea0b 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4702,8 +4702,13 @@ int skb_append_pagefrags(struct sk_buff *skb, struct page *page, if (skb_can_coalesce(skb, i, page, offset)) { skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size); } else if (i < max_frags) { + /* + * Don't use -EMSGSIZE, as callers would just retry with a new + * skb. + */ + if (!try_get_page(page)) + return -EFAULT; skb_zcopy_downgrade_managed(skb); - get_page(page); skb_fill_page_desc_noacc(skb, i, page, offset, size); } else { return -EMSGSIZE; @@ -7575,8 +7580,9 @@ static void skb_splice_csum_page(struct sk_buff *skb, struct page *page, * possible, copying them to fragments if not possible (such as if they're slab * pages). * - * Returns the amount of data spliced/copied or -EMSGSIZE if there's - * insufficient space in the buffer to transfer anything. + * Returns the amount of data spliced/copied, -EMSGSIZE if there's + * insufficient space in the buffer to transfer anything, or -EFAULT if we + * could not take a page reference. */ ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter, ssize_t maxsize) -- 2.56.0