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Wed, 10 May 2023 16:21:04 -0700 (PDT) MIME-Version: 1.0 References: <20230503013608.2431726-1-nphamcs@gmail.com> <20230503013608.2431726-3-nphamcs@gmail.com> <20230505133426.d70a6599d9a729496b68a70c@linux-foundation.org> <315e7ec2-169c-4c4b-93df-485380bc0852@app.fastmail.com> In-Reply-To: <315e7ec2-169c-4c4b-93df-485380bc0852@app.fastmail.com> From: Nhat Pham Date: Wed, 10 May 2023 16:20:53 -0700 Message-ID: Subject: Re: [PATCH v13 2/3] cachestat: implement cachestat syscall To: Arnd Bergmann Cc: Andrew Morton , Geert Uytterhoeven , Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org, bfoster@redhat.com, Matthew Wilcox , linux-api@vger.kernel.org, kernel-team@meta.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 971FE100010 X-Rspam-User: X-Rspamd-Server: rspam06 X-Stat-Signature: bm41shc41jazrokuya87ompwxoc5ftwj X-HE-Tag: 1683760865-915237 X-HE-Meta: U2FsdGVkX1971DUpdgzKQ+VwmoJQ2jieGfb2AabJY8rmw7EA6qncXFvo79g+91jQQ7A3X699hn24eauGTq4baiMfU1sawokcVH3vBsNT8oyQ6zP2zdLT40VUJApRaL8L2zF3A4UlSASi46YZEkVD3Hf9zKOXY57gwDhbDY9B45kJqOYjbqjzLPtA3ZUCWjj4WMe78Fio6Cth85dho1Q0rGU6lhbfYc1dvj6NXHlc/+shjDobHxRnVAs9Ybai4cJszxt0Dpp6aEBSRiQEDiILhGBvlS53+N+X481Z43+9gVu6k+7ZGt6dSqfVyHnNPxVLr4NlvXdtX5P7H0v7Hl761YE1bmjxn1C/0n0bPixnKhWanW6of/ssfIIBkecuExAoWc/q/8wc6BtMYCTSSv9swNuTWI232Ew+dt66pYJVC7aF5KL/9oVZX+I2GOhuyDmWsPOQnV6vmqmIhBQ209eEqPMYiPMcHW8mn7dv+q5a3hP27w4BidPZOFyXk/LUnNN0g2NigxiobViu5uRzs43s9Pt+xNtI9D4RaPWq4Ga+7AzCCjZqKqFgWbt0l9mjS5QMKDG0uuB5AGjI4vY1Y0KFQaKLI0uXQv/kID3096MngUsBDVbu0NATBH26CEPV/rGeSgOLoNUCfp8msHMGMHa7RZE6QgwvTvXul5c/d+oQovhUzg4pc5YsuiYF1V/Qb67sZqMhkj2UEm4IVWnCK4xAhCAIF2su6i8zAVtaOLwb5gZduyMyaQuuiJPv5MDrqObpQns19dUz6b1R9UOf6fSOUkvgsSaMguKAkjfT2itCMR5ctxj2mzRsyX496Fnnt9Qt+1bcG42/KwYBqoFkqaGGhqTJvGjPz6WoIs+7GdBCh1UEiag+zvbDdaZwXiqaH5X75Xt2Cf7ay3SooKSa8U07qCzK4l1JZOQMODixlLrDV2VMRhZBKXRtFGu5b5AtmJ9Psvcqyu1bR7+bv1C83F8 +HmbW4rU 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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: On Sat, May 6, 2023 at 10:35=E2=80=AFAM Arnd Bergmann wrote= : > > On Fri, May 5, 2023, at 22:34, Andrew Morton wrote: > > On Thu, 4 May 2023 19:26:11 +0200 Geert Uytterhoeven > > wrote: > > > >> > arch/x86/entry/syscalls/syscall_32.tbl | 1 + > >> > arch/x86/entry/syscalls/syscall_64.tbl | 1 + > >> > >> This should be wired up on each and every architecture. > >> Currently we're getting > >> > >> :1567:2: warning: #warning syscall cachestat not implemente= d [-Wcpp] > >> > >> in linux-next for all the missing architectures. > > > > Is that wise? We risk adding a syscall to an architecture without the > > arch maintainers and testers even knowing about it. > > > > The compile-time nag is there to inform the arch maintainers that a new > > syscall is available and that they should wire it up, run the selftest > > and then ship the code if they're happy with the result. > > The usual approach is for the author of a new syscall to > include a patch with all the architecture specific changes > and Cc the architecture maintainers for that. > > Note that half the architectures get the entry from > include/uapi/asm-generic/unistd.h, so adding it there > does not necessarily trigger adding each maintainer > from scripts/get_maintainer.pl. > > The only real risk in adding a new syscall is passing __u64 > register arguments that behave differently across > architectures, or using pointers to data structures that > require a compat handler on some architectures. I watch out > for those as they get sent to me or the linux-arch list, > and this one is fine. > > Arnd I took a stab at wiring the new syscall in this follow-up patch: https://lore.kernel.org/lkml/20230510195806.2902878-1-nphamcs@gmail.com/ Let me know if I missed something! Review and/or suggestion is very much appreciated.