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[2003:d8:2f37:2b00:948c:dd9f:29c8:73f4]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3d64ba4ff83sm5013587f8f.4.2025.09.01.06.43.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 01 Sep 2025 06:43:45 -0700 (PDT) Message-ID: Date: Mon, 1 Sep 2025 15:43:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] mm: Enable khugepaged to operate on non-writable VMAs To: Kiryl Shutsemau Cc: Dev Jain , akpm@linux-foundation.org, willy@infradead.org, hughd@google.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, baohua@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250901074817.73012-1-dev.jain@arm.com> <7towtl2pjubgdil4csn5rg3usbai5xvzz73wqkwj5b5awh2iim@wfvahykzjrlo> <9c3a2ecd-ceae-4e87-a6d7-6a7121ab7a15@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: jAd9rLvl1RlOP6Cu7t0Sf1PIDh0Z6gwbM7h0BrL6TDI_1756734226 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 4D702A0006 X-Stat-Signature: 1bhqo85pdg1tizbeokz8kszhrgs64a3y X-Rspam-User: X-HE-Tag: 1756734229-383367 X-HE-Meta: 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 rvgdh3M0 oK1WI0xrFku50OhQ0/cjnKMqWVz/g3Lej/8SHOuFuPIhGC59wXJdWjv8by5c3VD8M1F8UEkG0a8gsDZ+yMUQJFXdfUr+Q/alv9eiVPsE1t0OjAZV6cI5smDPZI7qvVBTRndk2 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 01.09.25 15:15, Kiryl Shutsemau wrote: > On Mon, Sep 01, 2025 at 10:32:34AM +0200, David Hildenbrand wrote: >> >>>> @@ -676,9 +676,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, >>>> writable = true; >>>> } >>>> - if (unlikely(!writable)) { >>>> - result = SCAN_PAGE_RO; >>>> - } else if (unlikely(cc->is_khugepaged && !referenced)) { >>>> + if (unlikely(cc->is_khugepaged && !referenced)) { >>>> result = SCAN_LACK_REFERENCED_PAGE; >>>> } else { >>>> result = SCAN_SUCCEED; >>>> @@ -1421,9 +1419,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, >>>> mmu_notifier_test_young(vma->vm_mm, _address))) >>>> referenced++; >>>> } >>>> - if (!writable) { >>>> - result = SCAN_PAGE_RO; >>>> - } else if (cc->is_khugepaged && >>>> + if (cc->is_khugepaged && >>> >>> The only practical use of the writable is gone. The only other usage is >>> tracing which can be dropped to as it is not actionable anymore. >>> >>> Could you drop writable? Maybe as a separate commit. >> >> I think we should just do it in the same patch. > > Change in trace_mm_collapse_huge_page_isolate() interface doesn't belong > to the same patch in my view. We frequently adjust tracing code (which is specific to khugepaged in this case) in the same patch. Anyhow, no strong opinion. -- Cheers David / dhildenb