From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5AF8AD29C28 for ; Mon, 19 Jan 2026 13:24:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 512DE6B019F; Mon, 19 Jan 2026 08:24:12 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4D41A6B01A0; Mon, 19 Jan 2026 08:24:12 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3E2506B01A1; Mon, 19 Jan 2026 08:24:12 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 2F3076B019F for ; Mon, 19 Jan 2026 08:24:12 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id D6E56C017E for ; Mon, 19 Jan 2026 13:24:11 +0000 (UTC) X-FDA: 84348781902.22.15079A9 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf04.hostedemail.com (Postfix) with ESMTP id B8E5C40009 for ; Mon, 19 Jan 2026 13:24:09 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf04.hostedemail.com: domain of kevin.brodsky@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=kevin.brodsky@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1768829050; a=rsa-sha256; cv=none; b=QCbvD6lgf9AibygBd5QsQzMKVCYRIeBVVFgmjJ+n++V4umP66Z6/0MnvKzctc2Na74dMvo lGj/axh7qXwAvdao6tbzbVOpSu49YdjE37pgPb2qm5SnGLHz+oiKAsMtfXb4mOQSxFA5hX xAifo4U0vEb1c9aB9DQfvo1zLlBVHmc= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf04.hostedemail.com: domain of kevin.brodsky@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=kevin.brodsky@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1768829050; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=jor/QInlEX+fsL9YlpJ8E8qDgLYYTGfnxOUzoIgOonw=; b=EQzoqPpnd5rVMGR1Q4z85Tyc0DmjMak9T9vcPsc1AS7cvQHJD9udRvHpvbaEf3fvZcANuJ 0oSzwHveADRnX1IRImxLcuKgQxKXZ6j0QcagqxSHO0PvJOVZK8xN7eE2pIrXIn1So3FnRs 3k5V+Nj1dK/ytqLFA+JZtVeWq8j8Qo8= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E6C7E497; Mon, 19 Jan 2026 05:24:01 -0800 (PST) Received: from [10.44.160.85] (e126510-lin.lund.arm.com [10.44.160.85]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5CD3D3F740; Mon, 19 Jan 2026 05:24:06 -0800 (PST) Message-ID: <4d3361e4-90e8-409f-bde5-b09de53137b1@arm.com> Date: Mon, 19 Jan 2026 14:24:03 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 4/8] selftests/mm: fix usage of FORCE_READ() in cow tests To: "David Hildenbrand (Red Hat)" , linux-mm@kvack.org, linux-kselftest@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Lorenzo Stoakes , Mark Brown , Ryan Roberts , Shuah Khan References: <20260107164842.3289559-1-kevin.brodsky@arm.com> <20260107164842.3289559-5-kevin.brodsky@arm.com> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: B8E5C40009 X-Rspamd-Server: rspam06 X-Stat-Signature: zfdzp83jw39xky3snje8o6ezr6qfdkeq X-Rspam-User: X-HE-Tag: 1768829049-950757 X-HE-Meta: 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 HURBjK6H Vy4BbHmWDP1egJU9Sp6Zk898YNE76XDd8K4GdMbgPONk5fuj2pUaQ89olG3vU9/eQ7ABaeMZw+57t9Ofd2I0TWGyqSZBp1Do8H3Ns8QnmDRnxJ46BAonpNWBZk7SKAhb5ekbai4if20VC4wKrjdJQ/wqFrYD/TXd0ZqZHC4ngYSl1E0euvv9+JzwUEgzjm+5eOx6h 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 19/01/2026 11:50, David Hildenbrand (Red Hat) wrote: > On 1/7/26 17:48, Kevin Brodsky wrote: >> Commit 5bbc2b785e63 ("selftests/mm: fix FORCE_READ to read input >> value correctly") modified FORCE_READ() to take a value instead of a >> pointer. It also changed most of the call sites accordingly, but >> missed many of them in cow.c. In those cases, we ended up with the >> pointer itself being read, not the memory it points to. >> >> No failure occurred as a result, so it looks like the tests work >> just fine without faulting in. However, the huge_zeropage tests >> explicitly check that pages are populated, so those became skipped. > > Right, that's nasty! Thanks! > > For all cases, we could probably just fail if the memory is not > populated after FORCE_READ(). > > Would you have time to prepare a patch for that? Sure, I guess we could even have a helper that performs a FORCE_READ() and then returns the result of pagemap_is_populated(). - Kevin