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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 References: <20250827220141.262669-1-david@redhat.com> <20250827220141.262669-19-david@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: f8Wk0LuN1KgRWM6a0zTHMSDYEsbEths--oz6r5xpqPU_1756474904 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 7E32F1C0005 X-Rspam-User: X-Stat-Signature: 6hdh469ooxamat8nbdbhuzs3q5ezsxob X-Rspamd-Server: rspam09 X-HE-Tag: 1756474907-882310 X-HE-Meta: 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 YGbx8pLk tsN/F9sWTQ4Sf9Tkr/j73C3kUciAK1qOcDbNVMCJSPqbEAVEjNAqOFobCwKWlZPHADCrWJbwgmhU0c4YRxGZxuTVUXTPg3kz180NupBHBZTSVdJ3MoM3bbWBtiKhkYBuuFYFUKf3wPnD5MM9Yy4emo+UJobWmTWFvoOIv5YzBrLQY2OeNsKQb6hfSJmSBFuW6jutTIDyfGzgnirXG2JeJbAM4Jv/UgKzYFYkykbvQ9MZMy2k4z/zdM7TWCLm97ldJhb59YDGAvyKcM0RRv1UgLWomyfyICQrT/KJb8EwRoxRD3CE1HeSn2c5FhdwK7W+T6QPAVZbzCZQJ98PppURKhzUhom/IhaxT9AqE3X4V0giZnMNUF/162G4RmWflyTX6T6unEvJzeMoWKw4Dgwzh5E/uRubI0e/0PhSQuvkgEa7TjDC9q6rqGDRdWkKtPkNrKbBz/A1tUnU10P4Jx7syrI0K46QyvBanAaWejYIvEX/LQ60= 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: On 28.08.25 18:37, Lorenzo Stoakes wrote: > On Thu, Aug 28, 2025 at 12:01:22AM +0200, David Hildenbrand wrote: >> nth_page() is no longer required when iterating over pages within a >> single folio, so let's just drop it when recording subpages. >> >> Signed-off-by: David Hildenbrand > > This looks correct to me, so notwithtsanding suggestion below, LGTM and: > > Reviewed-by: Lorenzo Stoakes > >> --- >> mm/gup.c | 7 +++---- >> 1 file changed, 3 insertions(+), 4 deletions(-) >> >> diff --git a/mm/gup.c b/mm/gup.c >> index b2a78f0291273..89ca0813791ab 100644 >> --- a/mm/gup.c >> +++ b/mm/gup.c >> @@ -488,12 +488,11 @@ static int record_subpages(struct page *page, unsigned long sz, >> unsigned long addr, unsigned long end, >> struct page **pages) >> { >> - struct page *start_page; >> int nr; >> >> - start_page = nth_page(page, (addr & (sz - 1)) >> PAGE_SHIFT); >> + page += (addr & (sz - 1)) >> PAGE_SHIFT; >> for (nr = 0; addr != end; nr++, addr += PAGE_SIZE) >> - pages[nr] = nth_page(start_page, nr); >> + pages[nr] = page++; > > > This is really nice, but I wonder if (while we're here) we can't be even > more clear as to what's going on here, e.g.: > > static int record_subpages(struct page *page, unsigned long sz, > unsigned long addr, unsigned long end, > struct page **pages) > { > size_t offset_in_folio = (addr & (sz - 1)) >> PAGE_SHIFT; > struct page *subpage = page + offset_in_folio; > > for (; addr != end; addr += PAGE_SIZE) > *pages++ = subpage++; > > return nr; > } > > Or some variant of that with the masking stuff self-documented. What about the following cleanup on top: diff --git a/mm/gup.c b/mm/gup.c index 89ca0813791ab..5a72a135ec70b 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -484,19 +484,6 @@ static inline void mm_set_has_pinned_flag(struct mm_struct *mm) #ifdef CONFIG_MMU #ifdef CONFIG_HAVE_GUP_FAST -static int record_subpages(struct page *page, unsigned long sz, - unsigned long addr, unsigned long end, - struct page **pages) -{ - int nr; - - page += (addr & (sz - 1)) >> PAGE_SHIFT; - for (nr = 0; addr != end; nr++, addr += PAGE_SIZE) - pages[nr] = page++; - - return nr; -} - /** * try_grab_folio_fast() - Attempt to get or pin a folio in fast path. * @page: pointer to page to be grabbed @@ -2963,8 +2950,8 @@ static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr, if (pmd_special(orig)) return 0; - page = pmd_page(orig); - refs = record_subpages(page, PMD_SIZE, addr, end, pages + *nr); + refs = (end - addr) >> PAGE_SHIFT; + page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); folio = try_grab_folio_fast(page, refs, flags); if (!folio) @@ -2985,6 +2972,8 @@ static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr, } *nr += refs; + for (; refs; refs--) + *(pages++) = page++; folio_set_referenced(folio); return 1; } @@ -3003,8 +2992,8 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr, if (pud_special(orig)) return 0; - page = pud_page(orig); - refs = record_subpages(page, PUD_SIZE, addr, end, pages + *nr); + refs = (end - addr) >> PAGE_SHIFT; + page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); folio = try_grab_folio_fast(page, refs, flags); if (!folio) @@ -3026,6 +3015,8 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr, } *nr += refs; + for (; refs; refs--) + *(pages++) = page++; folio_set_referenced(folio); return 1; } The nice thing is that we only record pages in the array if they actually passed our tests. -- Cheers David / dhildenb