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[2003:d8:2f23:5600:727b:b2f6:94a1:a51b]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3ee0fbc72e6sm6332457f8f.29.2025.09.19.00.24.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 19 Sep 2025 00:24:36 -0700 (PDT) Message-ID: Date: Fri, 19 Sep 2025 09:24:34 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Patch v2 1/2] mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL To: Wei Yang , akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, xu.xin16@zte.com.cn Cc: linux-mm@kvack.org, Kiryl Shutsemau References: <20250919071244.17020-1-richard.weiyang@gmail.com> <20250919071244.17020-2-richard.weiyang@gmail.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: <20250919071244.17020-2-richard.weiyang@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: O-W5z-uoMtLJwI_0jfvD6q6tshf-b9pXh0za4p9_vQU_1758266677 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: rspam08 X-Rspamd-Queue-Id: 910E81A0009 X-Stat-Signature: fz4ypred3e9nponznc9ewy4gyh5f5efy X-Rspam-User: X-HE-Tag: 1758266680-327215 X-HE-Meta: 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 tc6llMaN Pb1b+T6TKYa0beMQxK554MYkEKXPmGbS3WKGcaJXUbXhdYQhAOXuRkPFhuxIYvxc9/s6Y8r5uqF7pWUGBw0Lt6DhCPoOKsTN/JW6bfm3F3Q5fs3u1djNfs3PPQp9IGKrWxD9Ysq3lU8kiekaUO34iLQzfheY6GEtvnH99g9nU5h5K43YIl9lp6kNGAHq/Iii5CLF7wwSU/EOk2S6GmgkiXlbUo3WZG7v7uPBe2pR9OKD2OOGi5EKrpEsZPA5v5i0SCikjj3ZeqcW3K3MrW9EfqZGQkwS+XbjuwfQYU0oUwh1xG/lFlYL/UZeVetCkyXS+jpE12rc7nSyD3ZM= 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 19.09.25 09:12, Wei Yang wrote: > When using mm_slot in ksm, there is code snip like: > > slot = mm_slot_lookup(mm_slots_hash, mm); > mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot); > if (mm_slot && ..) { > } > > The mm_slot_entry() won't return a valid value if slot is NULL > generally. But currently it works since slot is the first element of > struct ksm_mm_slot. > > To reduce the ambiguity and make it robust, access mm_slot_entry() when > slot is !NULL. > > Signed-off-by: Wei Yang > Cc: Lance Yang > Cc: David Hildenbrand > Cc: Dev Jain > Cc: Kiryl Shutsemau > Cc: xu.xin16@zte.com.cn > > --- > v2: > * check on slot before continue > --- As discussed, we might want to do some other cleanups in that areas (e.g., slot never being NULL?). But this here looks cleaner to me for the time being. Acked-by: David Hildenbrand -- Cheers David / dhildenb