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b=XvmUlgCeoCPflDec486GmACayjS9XAXdVi4jQ5IGEwCB7UpM1DdwzIDwrOBUViHzI 97NKK4HSiiPZrhyqy8P7jPQKyxOkz6xrPrftOcT313kroGAY3uZSo538yAqnpKPCOq yVvmyiWKONxCUbWAhcPwg8zCIzeb9dW9eYwjp2vs= Date: Wed, 16 Jul 2025 15:15:43 -0700 From: Andrew Morton To: wang lian Cc: broonie@kernel.org, david@redhat.com, lorenzo.stoakes@oracle.com, sj@kernel.org, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, brauner@kernel.org, jannh@google.com, Liam.Howlett@oracle.com, shuah@kernel.org, vbabka@suse.cz, ludovico.zy.wu@gmail.com, gkwang@linx-info.com, p1ucky0923@gmail.com, ryncsn@gmail.com, zijing.zhang@proton.me Subject: Re: [PATCH] selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" Message-Id: <20250716151543.998b121a58064011e9ce68cb@linux-foundation.org> In-Reply-To: <20250716123126.3851-1-lianux.mm@gmail.com> References: <20250716123126.3851-1-lianux.mm@gmail.com> 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-Rspamd-Queue-Id: 4E87B40004 X-Stat-Signature: ocgf5jr5n5356gigr8s7k8w7pxyany7n X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1752704146-958761 X-HE-Meta: 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 xUhYEWqh ic0X7x03iDRuPeZTEDfspObUILAaX28Y2bAjzgBOGyCUwQT/BXMZnw0yKt+rRnW87ybcQ2RgscyufMHTFkJmZCY5V+vs49DTVlpozEl+Bn//reqkzXSH9Rdj01abxTItmcsWyEwcuWBgFOMuVevPAIZIT5ZBCDfp+SvqARjfRJmwT+VTbCJK9ak4+9HMCpl+lmpWYlPnhuWIyfOYj3Su2wq+sUhskZ81s/0MaHt9TuXN6qBYLBs9DxKJySxsMs2TNj7UW1G5HV9BC1Sx4Xmhvvk8e1ltBThsfqAD2aj4OHRPcneQI+PGc9uFslCPw2Ht8BAw4VnH52nY2hNDXceGV68V98EOG4BDueW863NdNGd9bgiYA6MU5K1ygipeAnlYb0sybv9R0x4wMLdhuQUnKlUUb045/W62pSXWY 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: On Wed, 16 Jul 2025 20:31:26 +0800 wang lian wrote: > Several mm selftests use the `asm volatile("" : "+r" (variable));` > construct to force a read of a variable, preventing the compiler from > optimizing away the memory access. This idiom is cryptic and duplicated > across multiple test files. > > Following a suggestion from David[1], this patch refactors this > common pattern into a FORCE_READ() macro > > tools/testing/selftests/mm/cow.c | 30 +++++++++---------- > tools/testing/selftests/mm/hugetlb-madvise.c | 5 +--- > tools/testing/selftests/mm/migration.c | 13 ++++---- > tools/testing/selftests/mm/pagemap_ioctl.c | 4 +-- > .../selftests/mm/split_huge_page_test.c | 4 +-- > 5 files changed, 24 insertions(+), 32 deletions(-) The patch forgot to move the FORCE_READ definition into a header?