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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 v1 33/36] mm/gup: drop nth_page() usage in unpin_user_page_range_dirty_lock() Date: Thu, 28 Aug 2025 00:01:37 +0200 Message-ID: <20250827220141.262669-34-david@redhat.com> In-Reply-To: <20250827220141.262669-1-david@redhat.com> References: <20250827220141.262669-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Rspamd-Queue-Id: CB7D5140008 X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: ptcfeqyigpb7bhhptr7wscnmapcoppok X-HE-Tag: 1756332700-347236 X-HE-Meta: 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 vlecOHte fSGI6ijWhjQWfLgumqVBfTfJuyoH57LAPVpi0/F2aCu60Nv2team1onDDiEEwiqkvg1sdUNHtligjc0uv3PkuJR3+7YCReTIPHU+BmKQmO/ttdwpnuqXs1uOJ5d31TV2+qBOkJH+qVbsmtULLIbY4iaqyzb/5KwRidTDqzn8irCnCzvjKwLgp44OxIY90wcRB4yHl 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: There is the concern that unpin_user_page_range_dirty_lock() might do some weird merging of PFN ranges -- either now or in the future -- such that PFN range is contiguous but the page range might not be. Let's sanity-check for that and drop the nth_page() usage. Signed-off-by: David Hildenbrand --- mm/gup.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/gup.c b/mm/gup.c index 89ca0813791ab..c24f6009a7a44 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -237,7 +237,7 @@ void folio_add_pin(struct folio *folio) static inline struct folio *gup_folio_range_next(struct page *start, unsigned long npages, unsigned long i, unsigned int *ntails) { - struct page *next = nth_page(start, i); + struct page *next = start + i; struct folio *folio = page_folio(next); unsigned int nr = 1; @@ -342,6 +342,9 @@ EXPORT_SYMBOL(unpin_user_pages_dirty_lock); * "gup-pinned page range" refers to a range of pages that has had one of the * pin_user_pages() variants called on that page. * + * The page range must be truly contiguous: the page range corresponds + * to a contiguous PFN range and all pages can be iterated naturally. + * * For the page ranges defined by [page .. page+npages], make that range (or * its head pages, if a compound page) dirty, if @make_dirty is true, and if the * page range was previously listed as clean. @@ -359,6 +362,8 @@ void unpin_user_page_range_dirty_lock(struct page *page, unsigned long npages, struct folio *folio; unsigned int nr; + VM_WARN_ON_ONCE(!page_range_contiguous(page, npages)); + for (i = 0; i < npages; i += nr) { folio = gup_folio_range_next(page, npages, i, &nr); if (make_dirty && !folio_test_dirty(folio)) { -- 2.50.1