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McKenney" Subject: Re: [PATCH v3 1/7] kernel/fork: convert vma assignment to a memcpy Message-Id: <20230125173449.5472cffc989dfab4b83c491d@linux-foundation.org> In-Reply-To: References: <20230125233554.153109-1-surenb@google.com> <20230125233554.153109-2-surenb@google.com> <20230125162159.a66e5ef05fecb405e85ffec9@linux-foundation.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: EC6951C0003 X-Stat-Signature: z8garywyfb56gt4akz8wjix483jbw7px X-HE-Tag: 1674696894-114306 X-HE-Meta: U2FsdGVkX18ElnF5E31yxRtTSeckZFYEW+jBjPIHOdZ1opVjDLt6+L5j0ha17vXSzypQlLKZNLcH9bgwGgELnB4HZefDi8sGXYBmWMnTvdwjzyZMwEegP1CndE/u2wE5MFHZuyYtNWxRxFCOb8egPfTI6C3ngZUBebWGcy0998wEB09jLEleo2wxvMw9KJPbdYbB6mse9k26zhehIaX/PkDs/9J25XnP3NDE/5LS10MJWO6WnLWtAbvBa7ueyeHGvSmTZNvcogRhLDWeFA34cg/QN9+IAWmOGOEW3pXQaveZtcOk/Wr5m6YZvCLxmYRJKnP+ROKAG1wRRhopMD2kZFy2DZZvaOP7qwk8LTUBPMZdPloi+0SRc1Bte6zdKTLyNMwDo8f36fShAzzMKBlDm0rqWK2VOR5yb3Fal3VlqkfqZ94LMOH9Mq5V7GYiX6k7yuSxCFq3SzWPkNJn+kk0SdA3TsSTDn62MpoiLN/GmCoorn03+wIT04oBjeTWE+MpDJlv4khxbDbLpZM/uLdkafLthX+JPj9Z2xZy6NmdSmK310JWhqwG+68GwSsnK3IX69ispLsk/mg4NKgaRJ/YBnapRzfT+jCpSBXKIW+SR8pelnPjXjyzIxvmIQZEG6amouPynEfQ/YZoC9VcjZe1h3GDlEPcu/O7yjuIE4H5MO0xHCuavNeJSxloZAYen/tb9xQMwDm6gMHuV5slvqj3/O/WwXC8tonl3HiitoAOzdh+Fm2rmuRY0E1CEEYRng6r6G39iwQJYS9nKH8GcnoeNgUnaWmDJBwuKDRhG9DkKm4cYfzFiI7ZwmsevEtzjCVrpyxk1Jnsk6xvtVZkqwL6gBL/+E+ytqgf9ChEZtqVVpWbILfpjKtgc3UZHC+MF3Hrw/GBemfHqfi0bLA+3jA7AnV1c7AUs8d0/wpmoYVAlvXBSBQ8pXND7D7KqDI2weFh5WuhFZSeGXLDUhdfl+h ANK/cGfC YsWguC8K4CitERQYsQM40h6V67Pc8oJ8N0KH/x+IhuCZrqW5QiDiUI49PdYszcbTmvhA0y7v0400wOgEf759Q3zi6/2KX4z6ZuclFUbS1UEtxqUmDsf+f0jd2aqF+AKWWL/eSCpPD+E6b7YZEu9RIE8JCEEqK1vRTt2xO/PXGVc0ycabTc8KfrPQJqDd6NN33Xx8+eGRyffdmxOUp+vp9GFheu4UqsB56XRBlVZbQq0tkbmBdoxTQ+RY+o6AI7pR+oUqQ1+ivSLKFsljEQZ4sHzZLZJf40zNA+OT//8Q44/JBuGaU6Q+g6q9iXEoyzrQ7ZcSj4YS8hAzBL3EkN6ig/KH8ZfVPyBAwcfjZoo0mt/9dOCNw7uAhkIK83gWHj0zMmqVGnXeelM5VVI/X/aCruVS24SZKFaXi9/E5lprLJpGfP/Y= 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 Wed, 25 Jan 2023 16:50:01 -0800 Suren Baghdasaryan wrote: > On Wed, Jan 25, 2023 at 4:22 PM Andrew Morton wrote: > > > > On Wed, 25 Jan 2023 15:35:48 -0800 Suren Baghdasaryan wrote: > > > > > Convert vma assignment in vm_area_dup() to a memcpy() to prevent compiler > > > errors when we add a const modifier to vma->vm_flags. > > > > > > ... > > > > > > --- a/kernel/fork.c > > > +++ b/kernel/fork.c > > > @@ -482,7 +482,7 @@ struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) > > > * orig->shared.rb may be modified concurrently, but the clone > > > * will be reinitialized. > > > */ > > > - *new = data_race(*orig); > > > + memcpy(new, orig, sizeof(*new)); > > > > The data_race() removal is unchangelogged? > > True. I'll add a note in the changelog about that. Ideally I would > like to preserve it but I could not find a way to do that. > Perhaps Paul can comment? I wonder if KCSAN knows how to detect this race, given that it's now in a memcpy. I assume so.