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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, 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 v2 34/37] mm/gup: drop nth_page() usage in unpin_user_page_range_dirty_lock() Date: Mon, 1 Sep 2025 17:03:55 +0200 Message-ID: <20250901150359.867252-35-david@redhat.com> In-Reply-To: <20250901150359.867252-1-david@redhat.com> References: <20250901150359.867252-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 12DD0A0004 X-Stat-Signature: dfjp1sdwe6xn879864y8ggiumzhqkxbm X-Rspam-User: X-HE-Tag: 1756739618-867645 X-HE-Meta: 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 /6JkyTgE oyzEM5b5InJgQfNJS0S6gubRiELZOYmIJWHz8wlVIwe3wORH0flVvxyDkRRBO1uZ0wwDtCP54EJ7UjEM+m+9JkyRBzJ7tFW7iyy2/kruD+dA+4YjFhF0AXvXG76srsUs2W6ll3ZItRKkq1QPNNGfJi27RthlS9kSN92H3766MOl4UDJD/Mx/wzs3mrirtDwWKMR6fwFMrFiw802KJpgwdbWNcV/eNeyoyt0/9vYvnIdtBp4j2YWf8JXs/MdRIK3d6pT/6JjlE9YUrOTttQZ5mPaQEMb+zng6lRrId+rV8+5MOX6sW+WoU4LUqehdQgdVe4P+wiDqcG0Xn6DKNFMgGPQE6zmoqYCuraRlisOV9vyff7xI= 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. Reviewed-by: Lorenzo Stoakes Signed-off-by: David Hildenbrand --- mm/gup.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/mm/gup.c b/mm/gup.c index f0f4d1a68e094..010fe56f6e132 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 +342,10 @@ 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 physically 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 +363,8 @@ 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