From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f170.google.com (mail-pl1-f170.google.com [209.85.214.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B5B51FB3; Wed, 6 Aug 2025 01:44:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754444670; cv=none; b=P31iH+TUZy10yJhb9I9MkKlE6O027Ztt1LBVfodyuZf0OPBMmvhLtd68ybsHwh+6H0DN4JblNsVBwjIsdazQsSC2KAgASvKToe+NBQnxhARhSkc0X2/Z3gRljYeDHhItGC7n+uf/j3cVCko0cEUU/iYTI5k06tz6QRKzREd/MQc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754444670; c=relaxed/simple; bh=w74FIGq0AXw75gXfOcQZe3mmzfSZaThuFNuCPXvRBdI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=GxD0Ov2722JefuT/JY7H/SaT8tdQFkW8quy9caN6WQq3B1zMB1pfARoDJcsKMFwk+iwkjwQ/Muwzy+rWX55fKRCIOjaBdlBoRGB4RoFRjMzN/7LUzhfyi3OCGOAqnyXJaqxJyPtpozU79cNca4H9fjx2Ue7Vc04iP4sLD7Nomzk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=A4UlhDjG; arc=none smtp.client-ip=209.85.214.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="A4UlhDjG" Received: by mail-pl1-f170.google.com with SMTP id d9443c01a7336-24003ed822cso36097135ad.1; Tue, 05 Aug 2025 18:44:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1754444669; x=1755049469; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=w74FIGq0AXw75gXfOcQZe3mmzfSZaThuFNuCPXvRBdI=; b=A4UlhDjGlXhcQzRq2SJ7Lhg8RPD8fGDDy6cFGB573jRGdjuWc857yFjCA79JfA8ytC nmw6zNNjD9TkA9pKlNjB9RsW2uO3R1YTA/SiIESThUfD6p29FkRr7soIauAp5Xh1otAV 3uYjxXU/UEWuHExBz5Sm6GYq6z1X8c8Q7NOGAqJzJtu/aPyAThhSTGq/awnfztLvWaR7 4Rt8hacWzCUhM23WY0Eyf6AZ3Uf+rRYZUKvw8bR3NoAQaaRjcp6iOj11Cc2x9ybcVTv7 48e8T2cf//WAQ6lRK3q3OsAwmwu4s6LzvUoNQurajZhnptRiEqrZlTfFTJFvOpDQv9KD IE0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1754444669; x=1755049469; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=w74FIGq0AXw75gXfOcQZe3mmzfSZaThuFNuCPXvRBdI=; b=qJq23P3KhlQXQFcRiOfD+mOAUrnKmbod02gJvn+s5H4/isJbTuYPm9yhZrPapVnkop BEj+Mn+xyw3qPHLCU78KTDfqAvVmbPMd/WizcFFU7qr+2z/8gOCPLzEr+4GO2E/79/80 3t334heGDOcaM2Iin163CtG8gQzGXsfNTP5vweW3a1nLBd01SP34j7C2oGj338X28WxY vqE2KNefuOxJBTeqYdKgVoRI6p50S4CcJvPk3vl7Dl1sAIkBcIG02HM3oSrgIO26xLu9 fu5hAj16KNQmNb+r3NBR23+OPT9LMQwqpRN3+FvXuhBpdSBymNkEmlsWYcxpoqw8p+8q VFNg== X-Forwarded-Encrypted: i=1; AJvYcCUA9IB7AgcRio+wbd7tIOAIz8b3qW/wHEvx2jgqOM+db1xMXP05KkDjBgie7j5pNj048DwfKf4BBsplK4eMxIIS@vger.kernel.org, AJvYcCWZfEIZJ6ECiQD8pgQlX4p0X96G+yw799x10oSbsuu3RnhEEuyTA6PwDe7DyNaH9LzvTqaKvUeJ4lf7V0A=@vger.kernel.org X-Gm-Message-State: AOJu0YzIHJXyuVvfccHEGsEw3OrzyKi/rT19OAngD8L4lja1JvLdOFrw fOltUKkVlSnoIbRq+fSQNChMSu8aCWW9LaaG+j5C7o1tXzjsifvFo+hH X-Gm-Gg: ASbGnctuzcv068JZnXfDXza/faPRirxPIhaz5je4CDMROkVUE3Tyiu2CP5H3No72JOX IVXXk2HPF6mXKjk3ygx/aVqfjGc2FtFmwdUC7AU5HNYvbHIwLYl2+27SfAzC6vADS2F+l1lcJBo 3qBJH+LGmv1skFXfUqX5g9SdjXSaBoLbCNgjbgL1LXSEirVQpl37c5LocgJGYwRCBqURJ3/7Tfd SwMGBNqdcIhzJAPyufe+tKryGyN5c5gnokVNv90AlFa5SufHelAU+RDdXPoDqSzaYo+PYytsLam aZm6XfBj2FYfxDqPd+vkqUG8Q9kn9ZqdIMwWlpDTLeHl5UOLvoXV2yNgf3RqcOdGJknnS9pDkmF vzTbij24xF170IYAQ2iyFWAPgrYeGeAYmcFfplQB7HWnhRg== X-Google-Smtp-Source: AGHT+IF57QVaXPLLcilicCteL+bMl77C52uViQHcrH/iqr0Corkc4MbpfAiii/PIkLD6ZK5p+aBAoA== X-Received: by 2002:a17:902:f691:b0:240:66ff:b253 with SMTP id d9443c01a7336-2429f55dcfdmr18204635ad.46.1754444668829; Tue, 05 Aug 2025 18:44:28 -0700 (PDT) Received: from localhost.localdomain ([2409:8900:21f8:86c:408a:124f:465a:e2e4]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-31f63ee0d77sm17890187a91.20.2025.08.05.18.44.23 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); 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> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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