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Fri, 06 Nov 2026 01:50:37 -0800 (PST) Received: from [192.168.1.22] ([83.231.69.9]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-492d3d60e78sm2755152f8f.1.2026.11.06.01.50.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 06 Nov 2026 01:50:37 -0800 (PST) Message-ID: <6662ae76-c8dc-4bc5-9730-bf9f537ca9cb@gmail.com> Date: Fri, 6 Nov 2026 10:50:34 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/5] mm: limit pagecache folio refcount when splicing into pipes To: "David Hildenbrand (Arm)" , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Jan Kara , 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 , Hugh Dickins , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , Jason Gunthorpe , Kevin Tian , "Joerg Roedel (AMD)" , Robin Murphy , Steve Sistare , John Hubbard Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, iommu@lists.linux.dev, stable@vger.kernel.org References: <20261105-refcount_overflow_stable-v1-0-70b9c655da3e@kernel.org> <20261105-refcount_overflow_stable-v1-2-70b9c655da3e@kernel.org> Content-Language: en-US From: "Jose A. Perez de Azpillaga" In-Reply-To: <20261105-refcount_overflow_stable-v1-2-70b9c655da3e@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: bgch6bkc73n38u86wnwikg86or3th8qc X-Rspam-User: X-Spam-Status: No, score=-8.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FORGED_GMAIL_RCVD,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 43F174000A X-HE-Tag: 1793958640-681704 X-HE-Meta: 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 hM3HDwh9 HaIstmvqMjBs7DykILRb6GTIopGAKyBVgXkSYsltc3vfMuyFuzn3k1LILQP9wqSW3e1yobV821deguumADbYTnxuZ8lIlC460ujRW38qjaWKp/MtSc9i+37imP0TdIEPcTqflMbtXk2P4zCc++wZ//ztEpOoAaGiEBSyY+uNgldt2+PGhmsXaD90bicGRS3n6m80ZePptXD09733X8k9vVpO+f9OVwcW+LFFUJuy70At2uNKxbtlP6/oW2ToyXzserwtBQHY72gDsDKUByHXRgLzrk09QW/rbSWyy/fvo8bCu6pWky9F5bI/G6QyS7oqH5NRlp6YAhwJsM+eJCTT1owL6Ep+YvvxhqM1DlrEp3JtW8RvNqHBWuGjyDihCY39hNv7Y6WFv8FOjYE2S4eLRktLw9cXqgajGZRWhVXDIG0KcU4r4jE7kPzEWdettD9hBc1q6GZMpIzHV52WRHR+G8EUfxUOV7LI7AlzPuVP3ZwcZ3eQ5Iz3rl5hFW+EsNM7jxMr+1JjbZEKyf+9GOuD3IWzuHIOxUq3BzcjSIPoj2dKo/lCqlUtdX495bg== 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 On 11/5/26 2:10 PM, David Hildenbrand (Arm) wrote: > Similar to mapping pagecache folios into page tables, let's reject splicing > folios into a pipe if the refcount is at it's limit, similar to how we > handle it during GUP. > > This will prevent more cases of possible folio refcount overflows with > large pagecache folios. > > Let's keep it simple and check in the two callers of > splice_folio_into_pipe(). > > Also check in try_get_page() to cover pipe-buffer duplication by tee() > and partial pipe-to-pipe splicing. > > 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 > Signed-off-by: David Hildenbrand (Arm) LGTM: Reviewed-by: Jose A. Perez de Azpillaga -- cheers, jose a. p-a