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Sun, 20 Sep 2020 08:55:42 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: William Kucharski Mime-Version: 1.0 (1.0) Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag Date: Sun, 20 Sep 2020 09:55:40 -0600 Message-Id: <76A432F3-4532-42A4-900E-16C0AC2D21D8@gmail.com> References: <20200920151510.GS32101@casper.infradead.org> Cc: Christoph Hellwig , Alexander Viro , Andrew Morton , Jens Axboe , Arnd Bergmann , David Howells , linux-arm-kernel@lists.infradead.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org In-Reply-To: <20200920151510.GS32101@casper.infradead.org> To: Matthew Wilcox X-Mailer: iPhone Mail (18B5052h) 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: I really like that as it=E2=80=99s self-documenting and anyone debugging it c= an see what is actually being used at a glance. > On Sep 20, 2020, at 09:15, Matthew Wilcox wrote: >=20 > =EF=BB=BFOn Fri, Sep 18, 2020 at 02:45:25PM +0200, Christoph Hellwig wrote= : >> Add a flag to force processing a syscall as a compat syscall. This is >> required so that in_compat_syscall() works for I/O submitted by io_uring >> helper threads on behalf of compat syscalls. >=20 > Al doesn't like this much, but my suggestion is to introduce two new > opcodes -- IORING_OP_READV32 and IORING_OP_WRITEV32. The compat code > can translate IORING_OP_READV to IORING_OP_READV32 and then the core > code can know what that user pointer is pointing to.