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=-10.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 68BCFC2D0E4 for ; Mon, 23 Nov 2020 13:29:22 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EE2E6206E3 for ; Mon, 23 Nov 2020 13:29:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="X8VkKcGK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EE2E6206E3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=1ix5jgkpkVph3nIX65CeHNYtgZUY5DBflkJID7TkYZ4=; b=X8VkKcGKTRZ3fPCRJfx06WPGE kjz2qQppjuE/C4ndetET6/7Zdj8RIV1GDVB8NyrjuYIXJX2aL+kHPA8axOO59+CFKznNn4tOPoqIq sB6vXItioGtQvEk7COg2nwnP+7Pjfa2r+PwcZHSYsxX9H6/CUz52c2lavo8uAl+VItuXUhD2QRWK8 CgLyK9Wd1zcMBMu1qJgaJ4eszz09LAx14emxm1q/XLSrYrX1PrcFrntf1c/gjuI5Qs1EW4h2jokm2 SZmhVCObdLOaJjcT4g53X7hDrPWdVV/+FpkjYjQP218GEUquspUP/5tPu/gxU5BwP2IKbabtUA5dt K9Aw4vQ5g==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1khBsw-0007Eq-F9; Mon, 23 Nov 2020 13:28:02 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1khBss-0007Dp-Mt for linux-arm-kernel@lists.infradead.org; Mon, 23 Nov 2020 13:27:59 +0000 Received: from gaia (unknown [95.146.230.165]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6D14220782; Mon, 23 Nov 2020 13:27:55 +0000 (UTC) Date: Mon, 23 Nov 2020 13:27:52 +0000 From: Catalin Marinas To: Will Deacon Subject: Re: [PATCH 1/6] arm64: pgtable: Fix pte_accessible() Message-ID: <20201123132752.GE17833@gaia> References: <20201120143557.6715-1-will@kernel.org> <20201120143557.6715-2-will@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201120143557.6715-2-will@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201123_082758_844877_8256B950 X-CRM114-Status: GOOD ( 13.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Yu Zhao , Anshuman Khandual , Peter Zijlstra , kernel-team@android.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux-mm@kvack.org, Minchan Kim , Linus Torvalds , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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: Catalin Marinas _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel