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[2003:d8:2f14:2400:afc:9797:137c:a25b]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-40c5c156a48sm1447555f8f.48.2025.09.24.03.10.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Sep 2025 03:10:48 -0700 (PDT) Message-ID: <1282de5a-3dce-443d-91d1-111103140973@redhat.com> Date: Wed, 24 Sep 2025 12:10:47 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mm-new 1/1] mm/khugepaged: abort collapse scan on non-swap entries To: Lance Yang , akpm@linux-foundation.org Cc: lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, dev.jain@arm.com, hughd@google.com, ioworker0@gmail.com, kirill@shutemov.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mpenttil@redhat.com, npache@redhat.com, ryan.roberts@arm.com, ziy@nvidia.com, richard.weiyang@gmail.com References: <20250924100207.28332-1-lance.yang@linux.dev> 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: <20250924100207.28332-1-lance.yang@linux.dev> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: uOMUTexBpiJke0heBlLC8s7HY93vEOeEr7SmdPVgOUQ_1758708649 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: 785D94000F X-Stat-Signature: oegzuizork5mwtgmxcppcsc34nbind3u X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1758708652-714423 X-HE-Meta: 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 q1FMmvg4 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 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 24.09.25 12:02, Lance Yang wrote: > From: Lance Yang > > The existing check in hpage_collapse_scan_pmd() is specific to uffd-wp > markers. Other special markers (e.g., GUARD, POISONED) would not be caught > early, leading to failures deeper in the swap-in logic. > > hpage_collapse_scan_pmd() > `- collapse_huge_page() > `- __collapse_huge_page_swapin() -> fails! > > As David suggested[1], this patch skips any such non-swap entries early. > If a special marker is found, the scan is aborted immediately with the > SCAN_PTE_NON_PRESENT result, as Lorenzo suggested[2], avoiding wasted > work. Note that I suggested to skip all non-present entries except swap entries, which includes migration entries, hwpoisoned entries etc. -- Cheers David / dhildenb