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[2003:d8:2f26:ba00:803:6ec5:9918:6fd]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-3c0748797acsm12277591f8f.10.2025.08.21.13.08.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Aug 2025 13:08:10 -0700 (PDT) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: David Hildenbrand , Alexander Potapenko , Andrew Morton , Brendan Jackman , Christoph Lameter , Dennis Zhou , Dmitry Vyukov , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, iommu@lists.linux.dev, io-uring@vger.kernel.org, Jason Gunthorpe , Jens Axboe , Johannes Weiner , John Hubbard , kasan-dev@googlegroups.com, kvm@vger.kernel.org, "Liam R. Howlett" , Linus Torvalds , linux-arm-kernel@axis.com, linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-ide@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Lorenzo Stoakes , Marco Elver , Marek Szyprowski , Michal Hocko , Mike Rapoport , Muchun Song , netdev@vger.kernel.org, Oscar Salvador , Peter Xu , Robin Murphy , Suren Baghdasaryan , Tejun Heo , virtualization@lists.linux.dev, Vlastimil Babka , wireguard@lists.zx2c4.com, x86@kernel.org, Zi Yan Subject: [PATCH RFC 23/35] scatterlist: disallow non-contigous page ranges in a single SG entry Date: Thu, 21 Aug 2025 22:06:49 +0200 Message-ID: <20250821200701.1329277-24-david@redhat.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250821200701.1329277-1-david@redhat.com> References: <20250821200701.1329277-1-david@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 2k9_GSYJtlfcGdcn8YmSj74KpAKQXROre3AMjaJyIs0_1755806892 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Rspamd-Queue-Id: E168D20004 X-Rspam-User: X-Stat-Signature: 16g19z49xjhmktir5gfhtrejz78dpuk8 X-Rspamd-Server: rspam09 X-HE-Tag: 1755806894-818995 X-HE-Meta: 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 7nN+U6Lt 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The expectation is that there is currently no user that would pass in non-contigous page ranges: no allocator, not even VMA, will hand these out. The only problematic part would be if someone would provide a range obtained directly from memblock, or manually merge problematic ranges. If we find such cases, we should fix them to create separate SG entries. Let's check in sg_set_page() that this is really the case. No need to check in sg_set_folio(), as pages in a folio are guaranteed to be contiguous. We can now drop the nth_page() usage in sg_page_iter_page(). Signed-off-by: David Hildenbrand --- include/linux/scatterlist.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 6f8a4965f9b98..8196949dfc82c 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -6,6 +6,7 @@ #include #include #include +#include #include struct scatterlist { @@ -158,6 +159,7 @@ static inline void sg_assign_page(struct scatterlist *sg, struct page *page) static inline void sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len, unsigned int offset) { + VM_WARN_ON_ONCE(!page_range_contiguous(page, ALIGN(len + offset, PAGE_SIZE) / PAGE_SIZE)); sg_assign_page(sg, page); sg->offset = offset; sg->length = len; @@ -600,7 +602,7 @@ void __sg_page_iter_start(struct sg_page_iter *piter, */ static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) { - return nth_page(sg_page(piter->sg), piter->sg_pgoffset); + return sg_page(piter->sg) + piter->sg_pgoffset; } /** -- 2.50.1