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[2001:b011:20e0:15d4:84b3:8c62:a0b8:199e]) by smtp.gmail.com with ESMTPSA id z15-20020a170903018f00b0015e8d4eb2easm445903plg.308.2022.05.20.20.50.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 May 2022 20:50:14 -0700 (PDT) Date: Sat, 21 May 2022 11:50:06 +0800 From: Chih-En Lin To: Christophe Leroy Cc: Andrew Morton , "linux-mm@kvack.org" , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Christian Brauner , "Matthew Wilcox (Oracle)" , Vlastimil Babka , William Kucharski , John Hubbard , Yunsheng Lin , Arnd Bergmann , Suren Baghdasaryan , Colin Cross , Feng Tang , "Eric W. Biederman" , Mike Rapoport , Geert Uytterhoeven , Anshuman Khandual , "Aneesh Kumar K.V" , Daniel Axtens , Jonathan Marek , Pasha Tatashin , Peter Xu , Andrea Arcangeli , Thomas Gleixner , Andy Lutomirski , Sebastian Andrzej Siewior , Fenghua Yu , David Hildenbrand , "linux-kernel@vger.kernel.org" , Kaiyang Zhao , Huichun Feng , Jim Huang Subject: Re: [RFC PATCH 2/6] mm: clone3: Add CLONE_COW_PGTABLE flag Message-ID: <20220521035006.GB1506735@strix-laptop> References: <20220519183127.3909598-1-shiyn.lin@gmail.com> <20220519183127.3909598-3-shiyn.lin@gmail.com> <7cb4c588-7a24-8557-6cd6-3ec59051c2b1@csgroup.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7cb4c588-7a24-8557-6cd6-3ec59051c2b1@csgroup.eu> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 20, 2022 at 02:13:25PM +0000, Christophe Leroy wrote: > > > Le 19/05/2022 à 20:31, Chih-En Lin a écrit : > > Add CLONE_COW_PGTABLE flag to support clone3() system call to enable the > > Copy-On-Write (COW) mechanism on the page table. > > Is that really something we want the user to decide ? Isn't it an > internal stuff that should be transparent for users ? > > As far as I know, there is no way today to decide whether you want COW > or not for main memory. Why should there be a choice for the COW of page > tables ? Agree. It should not expose to the user. COW of page table should become the configuration. Or, if the change is fine, it can even be the default setting. Thanks. --- Sorry I did not group reply the first time.