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Tue, 05 Aug 2025 18:44:28 -0700 (PDT) From: wang lian To: ziy@nvidia.com Cc: akpm@linux-foundation.org, brauner@kernel.org, broonie@kernel.org, david@redhat.com, jannh@google.com, liam.howlett@oracle.com, lianux.mm@gmail.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, richard.weiyang@gmail.com, ryncsn@gmail.com, shuah@kernel.org, sj@kernel.org, vbabka@suse.cz Subject: Re: [PATCH] selftests/mm: fix FORCE_READ to read input value correctly. Date: Wed, 6 Aug 2025 09:44:17 +0800 Message-Id: <20250806014417.19918-1-lianux.mm@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <6E5CCF4D-CB63-4E4C-BEDA-6FE533E0DFCD@nvidia.com> References: <6E5CCF4D-CB63-4E4C-BEDA-6FE533E0DFCD@nvidia.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 2A0E8C000D X-Stat-Signature: rdx9g1nzjgkp6qcmshjcybj8y5kztmra X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1754444669-88667 X-HE-Meta: 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 /xLJNDNL 0//mwuO4QblJ/1A80an2tZiLOoKRDxzuKcvp+5DjXoAPltuekzdJBOOA0JBjVDKJIePjuxCmpumiSnzNOVb2OYBb5u+G4cj9oVKKVuRaHfWVGK628HsYz949iRKfUFP2OegebVREfkmknpNcP+q1TOwrl7ZPgKLo5Ja7T3DILwI2PRE29TSfCuL5x0j817j6PSiNRo+JPXcW3Sa1BsBWOoOPwcxX1q6CGfu2Fbi43bfQJKGezHR+Lae+0yZKrmYy+PgM3v+dQhGk36+3AyRlCnYA+AcTTWtGqS6TFJK6tz01ujhcdXVP0ukToYemkpOn+pkreCveR7NOOpzv6hYmT25oli3GvvZFDBrbK72bIsRKEmBCTnv7oL0Z/8f+J2VaHzYsvaGcjGbysxL+3pKuC2MvEcq1krXM0zxlzWKDSlW7XxgmoWLnM0DXteQR3Nj9EvO1IX6GopkXiY6/a9d8/g39h3i/9f71kXkqwo+8IaJ6IkGco2EL/3xkANwZ0iuCmD+tCS1qUM7mIzoK8lWtKXWNKe6Z1fe67JA1iaXe8pEhjM/5oDcmBiDErieKeEY1LuPaE 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: List-Subscribe: List-Unsubscribe: Hi Zi Yan, Lorenzo, Thank you for the detailed discussion. I have been following the thread closely and it has been very insightful. Zi Yan's fix is excellent and I appreciate the rigorous analysis. Lorenzo's feedback has also deepened my own understanding of the subtleties around the FORCE_READ macro. Out of curiosity, I also checked the `(void)` prefixing on Godbolt. As Zi Yan concluded, the resulting assembly appears identical. I will be happy to join any future discussions regarding the exact behavior of volatile in this context. For this patch, it's definitely LGTM from my side as well, so. Reviewed-by:wang lian Thanks, wang lian