From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 98B1B41A923; Mon, 3 Aug 2026 14:02:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785765778; cv=none; b=U9ws0PLAQ9zvVhRu7HD3HCtX0wY0vrk9APUO9xWVd/FwE4Ld5ym4Kh7rbIsf+bHXprpHZRM36G9JroIym9OMKP43BOGV1rHDt/yFu5Z1Tsc6O7cP0pHxrnEkeZ6tICUIETAeK91ia/h8lThIKgQXOyVOLBNq4mDwFxxLHSwoYLk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785765778; c=relaxed/simple; bh=f4cGAhd7k5qtHe1oZeec12ODyNHt7DYn88bCYtwoRlg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Wv3WV8n7TYz2P8THRv2ld5uE3G2i/l2xmIbulZxh/yAqRWUnItcHT3/SOcCFb+iSQ740ooAZMh/Fk6H2cyKg7dZBLe7m/uD8ea9c54i8I/9P/0DazfqRg3pi2R8cfZrCWZVmQB1JZTYXQg9N92jr0FESy1B7KMtbakVPn1q3MRY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fSturGiZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fSturGiZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B07C1F000E9; Mon, 3 Aug 2026 14:02:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785765777; bh=T1E7dQ4aPZaIdq3SbmqgAHM9kCwev2hzByfcmJn3dpw=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=fSturGiZDOvtsXwaLNuF1cO1Im0uBGa354NwhqDC8M5d/qTsUxw1udoKLC54YCerx xT5pICzoM6YeHh4pTQURX0OvjgHTEvKdruMiu+xmZgPar+SXZGTbnEzQgZmIV9AToi nG7eNzHrJARTpUI5nj7ZtPYznsg6LshS6EdqSrjk/3KSvRdxTM+wQ5QSEkgvHOxzFM ruj+hzz/2bsg5p8WW2Ok+rT/+W+m2Ck5LU3CftpAP4Ct24z4DIWzTbMmK0kEBmuk9d mcrofLr8Pc5bZkK2wbnAqLH+Rrdx+GwjpcafR1QUHMYhtk1l3q9ilhNeMMNq+hT0Y1 1TQ2mG266LeNQ== Message-ID: <007258ed-3fd7-4d90-b909-6fdda15e0485@kernel.org> Date: Mon, 3 Aug 2026 16:02:45 +0200 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 07/15] mm/rmap: track whether the page VMA mapped pgoff is anonymous To: "Lorenzo Stoakes (ARM)" Cc: Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20260729-b4-scalable-cow-virt-pgoff-v3-0-e8ecfefea812@kernel.org> <20260729-b4-scalable-cow-virt-pgoff-v3-7-e8ecfefea812@kernel.org> <1b48cf7d-8906-43d4-a85d-5cfad10a12ac@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/3/26 15:51, Lorenzo Stoakes (ARM) wrote: > On Mon, Aug 03, 2026 at 12:57:44PM +0200, David Hildenbrand (Arm) wrote: >>> /* >>> - * Then at what user virtual address will none of the range be found in vma? >>> + * At what user virtual address will none of the range be found in vma? >>> * Assumes that vma_address() already returned a good starting address. >>> */ >>> static inline unsigned long vma_address_end(struct page_vma_mapped_walk *pvmw) >>> { >>> - struct vm_area_struct *vma = pvmw->vma; >>> - pgoff_t pgoff; >>> + const struct vm_area_struct *vma = pvmw->vma; >>> + const pgoff_t pgoff = pvmw->pgoff; >>> + pgoff_t pgoff_vma_start; >>> unsigned long address; >>> + pgoff_t pgoff_end; >>> >>> /* Common case, plus ->pgoff is invalid for KSM */ >>> if (pvmw->nr_pages == 1) >>> return pvmw->address + PAGE_SIZE; >>> >>> - pgoff = pvmw->pgoff + pvmw->nr_pages; >>> + pgoff_vma_start = vma_start_pgoff(vma); >>> + pgoff_end = pgoff + pvmw->nr_pages; >>> address = vma->vm_start + >>> - ((pgoff - vma_start_pgoff(vma)) << PAGE_SHIFT); >>> + ((pgoff_end - pgoff_vma_start) << PAGE_SHIFT); >>> /* Check for address beyond vma (or wrapped through 0?) */ >>> if (address < vma->vm_start || address > vma->vm_end) >>> address = vma->vm_end; >> >> Am I wrong or are all all changes here completely irrelevant for this patch? >> >> You mention >> >> "This is necessary in order to determine the correct VMA page >> offset in vma_address_end() when pvmw->nr_pages > 1." >> >> But I don't spot an effective change here. > > As per commit message: > > This is laying the groundwork for eventually using anonymous page offsets > as the index for all anonymous folios. > > No functional change intended. > > I cannot enable an effective change here, because if I did I'd break the kernel > and introduce a bisection hazard. You can just throw in a patch that cleans that up and avoids messing with confusing pgoff? -- Cheers, David