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b=eTt5PD3qX+gV8oN2bQfrKTUXG12fxCb2g8CCJ0RIs1IiAXdScPRGHEVzNqCUF0EfF vn9AtTcQJyeVFLHiyS7TT/pFwdLkp/l21H6gQj6rLcUlQa8Cl7GfkO28ct04G4EOe1 pWvqtGdg5v6MOlhNaycZkX+TOrDab5/XHcuj96jTgwxHB3+oCLbNVMbENuWyb5AiCr SNdjyF9uxlFht1HGGXwbyNWFZNOk2a1iHA8wqQ5rWSxKfIqPAmhCrbvrmmPeFd+3zV cH1u3llfUenlu/FzNNlHHXUElF83E+C+K4Gl2pAlKRdjvZRDtq+WYe7cqMnKCuJg/U +PbBMsRZLGZTw== Message-ID: <3420eb9b-2523-4a6e-bc49-d6fcbe5cfda0@kernel.org> Date: Mon, 13 Jul 2026 16:08:00 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 00/34] mm: optimize unnecessary loads due to ptep_get() and friends out To: Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-arch@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, x86@kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-openrisc@vger.kernel.org Cc: linux@armlinux.org.uk, akpm@linux-foundation.org, ankur.a.arora@oracle.com, rppt@kernel.org, linmag7@gmail.com, chleroy@kernel.org, klarasmodin@gmail.com, chenhuacai@kernel.org, kernel@xen0n.name, kas@kernel.org, zhangtianyang@loongson.cn, wangyuli@aosc.io, tsbogend@alpha.franken.de, ljs@kernel.org, jgg@ziepe.ca, catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de, ryan.roberts@arm.com, pasha.tatashin@soleen.com, rmclure@linux.ibm.com, baolin.wang@linux.alibaba.com, tj@kernel.org, kevin.brodsky@arm.com, anup@brainfault.org, atish.patra@linux.dev, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, hannes@cmpxchg.org, mhocko@kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, kasong@tencent.com, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, ryabinin.a.a@gmail.com, glider@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, anshuman.khandual@arm.com, yang@os.amperecomputing.com, chaitanyas.prakash@arm.com, ardb@kernel.org, guoren@kernel.org, yang.li85200@gmail.com, viro@zeniv.linux.org.uk, dinguyen@kernel.org, schuster.simon@siemens-energy.com, wangruikang@iscas.ac.cn, junhui.liu@pigmoral.tech, muchun.song@linux.dev, vishal.moola@gmail.com, namcao@linutronix.de, pavel@kernel.org, djbw@kernel.org, yu-cheng.yu@intel.com, baolu.lu@linux.intel.com, Jonathan.Cameron@huawei.com, coxu@redhat.com, andreas@gaisler.com, liam@infradead.org, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, geert@linux-m68k.org, shorne@gmail.com, jonas@southpole.se, stefan.kristiansson@saunalahti.fi References: <20260713135614.1618183-1-yeoreum.yun@arm.com> 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: <20260713135614.1618183-1-yeoreum.yun@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 4epgfhp6mrsg5m6nnu8y19i6js65wdzh X-Rspamd-Queue-Id: 1BD3E1C000C X-Rspamd-Server: rspam01 X-Rspam-User: X-HE-Tag: 1783951697-135029 X-HE-Meta: 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 ZstueEem Qfw5kwn9msVl7GWPx1E1qDDAZirL89735CDMgdN1RD9PXAND/p/MLl3j5Ez0+yPQKCFXK8jo13+HzSWri6VQhNS6HbaqYTpE1mHWpMIwuh8J6JAGGsXfpE2nF4KbGZMy7O/tZgz/x2rsUs81E6+eBKJ+jyZdLyMF4GWb8ojd7VP2uY69ZOYFy23en95KJRoyVvZ9e2Xryrs15+kUfGyO1g1cN0zgiFFvqUOTyazqdXmMK31SGMYi3dDe87vYbZ097yqUWWG1/OwSdIKqwwIH/DNQ/VKSnaIoLwGh7JafzeYDXDOl6bFrbCNwfZZNaALK1FFaNrk7Rs6CbrcvWbNOltTHsk7/+1eQraoB9ZRoU23d/MvzkpK3LbqMY1sBkpIsef2tO Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > Future work > =========== > - print_bad_page_map() and show_pte() still prints dummy values > instead of printing the same content for all generic compile-time > folded page tables. We might want to skip printing dummy values later. > > - We currently catch abuse of dummy values on the stack at compile-time by > relying on constant propagation by the compiler. Usama's work [3] on using > distinct types for sw vs. hw PTEs could help here as well." Just adding here that this series was excessively build tested (both by me + Yeoreum and the friendly build bots), and primarily tested on arm64 only so far with differing page table level configurations. There is the chance that there might still be some odd configs that reveal set_pgd() etc places to rework: so the build bots better should chew some more on this. I want to do some more testing, especially on x86 (32bit), but did not get to it yet. -- Cheers, David