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([2001:b07:6468:f312:9af8:e5f5:7516:fa89]) by smtp.googlemail.com with ESMTPSA id g25-20020a50d0d9000000b005361a6da384sm1474069edf.19.2023.09.28.09.57.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 28 Sep 2023 09:57:24 -0700 (PDT) Message-ID: Date: Thu, 28 Sep 2023 18:57:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH 00/10] Fix confusion around MAX_ORDER To: Mikulas Patocka Cc: "Kirill A. Shutemov" , Andrew Morton , Mel Gorman , Vlastimil Babka , David Hildenbrand , quic_jhugo@quicinc.com, snitzer@kernel.org, dm , linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230315113133.11326-1-kirill.shutemov@linux.intel.com> <3c25ec6f-cd33-9445-a76f-6ec2c30755f5@redhat.com> <86e7f97a-ac6b-873d-93b2-1121a464989a@redhat.com> From: Paolo Bonzini In-Reply-To: <86e7f97a-ac6b-873d-93b2-1121a464989a@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: gohr159tn9z8qqe4qfjyt685ufwmji6t X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 880D11A002B X-HE-Tag: 1695920250-464885 X-HE-Meta: U2FsdGVkX18lwwFIsiimfh31pwWvYJHMv3uHeYfsJl1gQk/GKkPwKovKExZptf/SoJMsY6F38Aj+O+llbhU0UUizP2pKf8X0M4fNhdIgCgoFnaJj9Amxl8DgZwNUKBSaeAPLzx8pdJMechOgvnLOJ1E+faxsRRcD6G6/QT890gRm9P4QzGMHW+0m30ObN/qFlcpzz4MXfCFJlc20MBON/P2CqIqnPfiZBlB+55cyZHJP6rvNyyei1OOfcqztds0fRxYM+Znc8d2t0lBf6XzQ1OZv3QMCDx/CLI/AqlqYtRSNS22l+cLetPL7Cyo9V/QM+kbITgQN+JU0htBcg49OdhzhbQuyVMGYDzWTZ55UNTmoeYuHOsuDdXD5HfL4Nki4a59/d1lqmS8jj+fvmzknv6MB0WyYUQhVqCUk2Gc/qd99y2g+wTBQx2n1MrB1DSfNSyd3SmQwEDSNlpRlMBf+MgZtHs82V1VykQ95bgUuQGkUmrjPJPwVWK3ropvBKixLbQUf/YfYJuBsRIxmusqAXjvk/j4Z+hmPX82r6MHlIvLCAduv28t5p9MxImlEZEBUqD2eSlAGt1nvdX//xtyEx5Sm9DvrtcZH0OLYYjFmlg2c0k9kfSOU8r4Dg2y5xc0dDfBOpGc9GjsK1WjpgIFA2QetN3gg2pfsNqFaCVrBicGXfHyrAaQLASsKOinvIv4vJyNT8tRQsb8BxrcdduuncUBsYTyC+T/iQDHlTcRflsw3nV4PrTEzNa+tk/TXl4KvSVuYu4jTmKyuXQ8DL9GQLhLgGPiMc5pfvBaqvjDdpkaqem0zpu7L72Tc2WcXWazS/0VXB088loVk156aVmaDSUk8SNCV2zwSyo0r4g1JKvGGRUnAKvwC4z1mkyNJUTKnajgC11KN2AVMEIkEZqJuSj1rPvtcVn4xjeqwi+SpohtmPTQb3ex4k4TxqMQ0vhjBIHb6HZoO53uoLsqtqQ8 fM/3dxo5 TY+IG6p1whtyulvUBXuP+RoqyaqqZgYNlFfjQMWcv2lNy8h6rXXTxh3T8vZkdq2YYkE9llZKPsAHX6CsklKLmbkFADrjq24diMj/6dFbqa7Q8PK29He8I6/t3x5ArC1JwgSjYsbwryTslBYUMHkrM81MqEJH5+lmAUnyAXc4ICIqhRszUe+TkJIv3TthX03saYCH9vU5tlUDin1eT+J0Rua2O22ChYb4F7tirHQtAQO1T5Xh5C5TWgiuCXP4L0sjnxxIQuPP7+czPPd0UP57FsNGeJs7+URtgQJwrgqRpxVptq8WhSikwPF52/VWbjaV9vTHHZW5bg/B460ZKspEswv9P9rgrPXTGd51FVXNMvXZPYG6UKh7687omylUAhuB+FrzO4IIVqxxyUZIwnmv/rLwcupPZovBT0eu4lxHLQvplFTM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000060, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 9/28/23 09:50, Mikulas Patocka wrote: >>> Fix the bugs and then change the definition of MAX_ORDER to be >>> inclusive: the range of orders user can ask from buddy allocator is >>> 0..MAX_ORDER now. > I think that exclusive MAX_ORDER is more intuitive in the C language - > i.e. if you write "for (i = 0; i < MAX_ORDER; i++)", you are supposed to > loop over all allowed values. If you declare an array "void > *array[MAX_ORDER];" you are supposed to hold a value for each allowed > order. > > Pascal has for loops and array dimensions with inclusive ranges - and it > is more prone to off-by-one errors. I agree it's somewhat confusing either way but the ship has sailed, the patch has been included in Linux for several months. Paolo