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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pKkeP-0066hH-0o; Wed, 25 Jan 2023 18:37:37 +0000 Date: Wed, 25 Jan 2023 18:37:36 +0000 From: Matthew Wilcox To: Suren Baghdasaryan Subject: Re: [PATCH v2 1/6] mm: introduce vma->vm_flags modifier functions Message-ID: References: <20230125083851.27759-1-surenb@google.com> <20230125083851.27759-2-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Mailman-Approved-At: Thu, 26 Jan 2023 08:53:08 +1100 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: michel@lespinasse.org, nvdimm@lists.linux.dev, heiko@sntech.de, leewalsh@google.com, dri-devel@lists.freedesktop.org, perex@perex.cz, jglisse@google.com, arjunroy@google.com, m.szyprowski@samsung.com, linux-arch@vger.kernel.org, qianweili@huawei.com, linux-samsung-soc@vger.kernel.org, aneesh.kumar@linux.ibm.com, chenhuacai@kernel.org, kasan-dev@googlegroups.com, linux-acpi@vger.kernel.org, rientjes@google.com, xen-devel@lists.xenproject.org, devel@lists.orangefs.org, robdclark@gmail.com, minchan@google.com, robert.jarzmik@free.fr, linux-um@lists.infradead.org, etnaviv@lists.freedesktop.org, npiggin@gmail.com, alex.williamson@redhat.com, viro@zeniv.linux.org.uk, luto@kernel.org, gthelen@google.com, tglx@linutronix.de, ldufour@linux.ibm.com, linux-sgx@vger.kernel.org, martin.petersen@oracle.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-crypto@vger.kernel.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, linux-medi a@vger.kernel.org, freedreno@lists.freedesktop.org, joelaf@google.com, linux-aio@kvack.org, linux-fbdev@vger.kernel.org, linux-ia64@vger.kernel.org, david@redhat.com, dave.hansen@linux.intel.com, virtualization@lists.linux-foundation.org, edumazet@google.com, target-devel@vger.kernel.org, punit.agrawal@bytedance.com, linux-s390@vger.kernel.org, dave@stgolabs.net, deller@gmx.de, hughd@google.com, andrii@kernel.org, patrik.r.jakobsson@gmail.com, linux-stm32@st-md-mailman.stormreply.com, linux-rockchip@lists.infradead.org, linux-graphics-maintainer@vmware.com, kernel-team@android.com, jayalk@intworks.biz, soheil@google.com, selinux@vger.kernel.org, linux-arm-msm@vger.kernel.org, mripard@kernel.org, shakeelb@google.com, haojian.zhuang@gmail.com, loongarch@lists.linux.dev, linux-arm-kernel@lists.infradead.org, tytso@mit.edu, nico@fluxnic.net, muchun.song@linux.dev, hjc@rock-chips.com, mcoquelin.stm32@gmail.com, tatashin@google.com, mike.kravetz@oracle.com, songliubraving@fb.com, jasowang @redhat.com, alsa-devel@alsa-project.org, peterx@redhat.com, linux-tegra@vger.kernel.org, kraxel@redhat.com, will@kernel.org, dmaengine@vger.kernel.org, bhe@redhat.com, miklos@szeredi.hu, linux-rdma@vger.kernel.org, linux-staging@lists.linux.dev, amd-gfx@lists.freedesktop.org, gurua@google.com, dgilbert@interlog.com, xiang@kernel.org, pabeni@redhat.com, jejb@linux.ibm.com, quic_abhinavk@quicinc.com, bp@alien8.de, mchehab@kernel.org, linux-ext4@vger.kernel.org, tomba@kernel.org, hughlynch@google.com, sre@kernel.org, tfiga@chromium.org, linux-xfs@vger.kernel.org, zhangfei.gao@linaro.org, wangzhou1@hisilicon.com, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-erofs@lists.ozlabs.org, davem@davemloft.net, mhocko@suse.com, kvm@vger.kernel.org, mst@redhat.com, Peter Zijlstra , bigeasy@linutronix.de, alexandre.torgue@foss.st.com, dhowells@redhat.com, linux-mm@kvack.org, ray.huang@amd.com, adilger.kernel@dilger.ca, kuba@kernel.org, sparclinux@vger.kernel.org, airlie d@gmail.com, anton.ivanov@cambridgegreys.com, herbert@gondor.apana.org.au, linux-scsi@vger.kernel.org, richard@nod.at, x86@kernel.org, vkoul@kernel.org, mingo@redhat.com, axelrasmussen@google.com, intel-gfx@lists.freedesktop.org, daniel@ffwll.ch, paulmck@kernel.org, jannh@google.com, chao@kernel.org, maarten.lankhorst@linux.intel.com, liam.howlett@oracle.com, hdegoede@redhat.com, linux-mediatek@lists.infradead.org, matthias.bgg@gmail.com, vbabka@suse.cz, dimitri.sivanich@hpe.com, posk@google.com, lstoakes@gmail.com, peterjung1337@gmail.com, yoshfuji@linux-ipv6.org, linuxppc-dev@lists.ozlabs.org, dsahern@kernel.org, kent.overstreet@linux.dev, kexec@lists.infradead.org, tiwai@suse.com, krzysztof.kozlowski@linaro.org, tzimmermann@suse.de, hannes@cmpxchg.org, dmitry.baryshkov@linaro.org, johannes@sipsolutions.net, mgorman@techsingularity.net, linux-accelerators@lists.ozlabs.org, l.stach@pengutronix.de Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Jan 25, 2023 at 08:49:50AM -0800, Suren Baghdasaryan wrote: > On Wed, Jan 25, 2023 at 1:10 AM Peter Zijlstra wrote: > > > + /* > > > + * Flags, see mm.h. > > > + * WARNING! Do not modify directly. > > > + * Use {init|reset|set|clear|mod}_vm_flags() functions instead. > > > + */ > > > + unsigned long vm_flags; > > > > We have __private and ACCESS_PRIVATE() to help with enforcing this. > > Thanks for pointing this out, Peter! I guess for that I'll need to > convert all read accesses and provide get_vm_flags() too? That will > cause some additional churt (a quick search shows 801 hits over 248 > files) but maybe it's worth it? I think Michal suggested that too in > another patch. Should I do that while we are at it? Here's a trick I saw somewhere in the VFS: union { const vm_flags_t vm_flags; vm_flags_t __private __vm_flags; }; Now it can be read by anybody but written only by those using ACCESS_PRIVATE.