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 X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FSL_HELO_FAKE,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE9EAC2D0E4 for ; Fri, 20 Nov 2020 16:03:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9498322253 for ; Fri, 20 Nov 2020 16:03:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JDTeI2Nz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730024AbgKTQDZ (ORCPT ); Fri, 20 Nov 2020 11:03:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730017AbgKTQDZ (ORCPT ); Fri, 20 Nov 2020 11:03:25 -0500 Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B4C8C0613CF; Fri, 20 Nov 2020 08:03:25 -0800 (PST) Received: by mail-pf1-x441.google.com with SMTP id w6so8278696pfu.1; Fri, 20 Nov 2020 08:03:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=bj0gchYAEfT0+Zss9Gzer9LAxrhaB1wq8M6niTXF50w=; b=JDTeI2Nzm7KfLc714MsoPH/dE15KZ3FbOP5cQsl8FFwmzEqNa937LZgF3UoowN6J7i 9VzrS83m8oP+BOw47FNJ9lgAzuQ3bHkNTapn7fA85dx03sdrMOp6Vpv5cM8+8Yx0wF8B AsNO7TO94mz/3BW9ZeOpRsmy8XBiJnFhPQeC1RKwG6koTFCk9V/g90DNMmbVTyh7ELuV 0v7W0RK5uB6OJEBkkmDUw3Grit9njUDLWk6kBmqkmtO1ekv2ln9caEv04HiIbX0Ffz/R /soMYjFL0rG3JfC5Wh5JmGWBCr7kkXPJyFPaJUdsU3xLR6zsoIepOV9fof5g6FjQpSfz oFOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=bj0gchYAEfT0+Zss9Gzer9LAxrhaB1wq8M6niTXF50w=; b=lbnYSKsSE2TYOHHT6BWxmfqmQrs0QNSuT/ttdAsvGMjaQBw5MOc5R3iqnUGZbiQqX4 C6OQ2vF60SjMsj1WKkcxlaKzRJq0A91ddJDc3GTW0BWsYY0H2MhwGICLAeNmK+zxFixd G59MfgHPVtKx6PeUcTRv51VDcGoHJkacjcgcsq9UJZ3aT07JYZzHtIzO831lawO5P3ii 9XjwiV1S8QqDkh/OMH9wgPhfbx5khGopW2r1M5V8ZgL15w814OmLRI64Z0qAo7I45kEi 1kdSbhQ7mUeo2LeL+n31rTXgWCWhZny5KxQRJkLcsjYnV2qmUos47srBGqvJHBhKEhS4 W2pw== X-Gm-Message-State: AOAM5337S9iGd4sb50hJMBoA6Pxil/7IlhjbOR+gPy/O7kE0GD3txofT ZYVFWy3+3b+wc39Utqqy4//w+gAQLAM= X-Google-Smtp-Source: ABdhPJwFQONlyOMa1MFBt6YuwAcdMecVtaTisxvOp3hpZ2oZPZmdZOHYKkKxTV5jxJbHuP9YV0EmMQ== X-Received: by 2002:a17:90a:a090:: with SMTP id r16mr11067016pjp.179.1605888204706; Fri, 20 Nov 2020 08:03:24 -0800 (PST) Received: from google.com ([2620:15c:211:201:7220:84ff:fe09:5e58]) by smtp.gmail.com with ESMTPSA id q12sm4717890pjl.41.2020.11.20.08.03.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Nov 2020 08:03:23 -0800 (PST) Sender: Minchan Kim Date: Fri, 20 Nov 2020 08:03:21 -0800 From: Minchan Kim To: Will Deacon Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, Catalin Marinas , Yu Zhao , Peter Zijlstra , Linus Torvalds , Anshuman Khandual , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org Subject: Re: [PATCH 1/6] arm64: pgtable: Fix pte_accessible() Message-ID: <20201120160321.GB3377168@google.com> References: <20201120143557.6715-1-will@kernel.org> <20201120143557.6715-2-will@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201120143557.6715-2-will@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 20, 2020 at 02:35:52PM +0000, Will Deacon wrote: > pte_accessible() is used by ptep_clear_flush() to figure out whether TLB > invalidation is necessary when unmapping pages for reclaim. Although our > implementation is correct according to the architecture, returning true > only for valid, young ptes in the absence of racing page-table > modifications, this is in fact flawed due to lazy invalidation of old > ptes in ptep_clear_flush_young() where we elide the expensive DSB > instruction for completing the TLB invalidation. > > Rather than penalise the aging path, adjust pte_accessible() to return > true for any valid pte, even if the access flag is cleared. > > Cc: > Fixes: 76c714be0e5e ("arm64: pgtable: implement pte_accessible()") > Reported-by: Yu Zhao > Signed-off-by: Will Deacon Reviewed-by: Minchan Kim