From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=aZej=6W=vger.kernel.org=linux-acpi-owner@kernel.org>
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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED,
	HEADER_FROM_DIFFERENT_DOMAINS,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 9AD61C38A2A
	for <linux-acpi@archiver.kernel.org>; Fri,  8 May 2020 19:11:15 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [23.128.96.18])
	by mail.kernel.org (Postfix) with ESMTP id 7A7E5218AC
	for <linux-acpi@archiver.kernel.org>; Fri,  8 May 2020 19:11:15 +0000 (UTC)
Authentication-Results: mail.kernel.org;
	dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ZFIdwDhl"
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1726877AbgEHTLP (ORCPT <rfc822;linux-acpi@archiver.kernel.org>);
        Fri, 8 May 2020 15:11:15 -0400
Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35636 "EHLO
        lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL)
        by vger.kernel.org with ESMTP id S1726767AbgEHTLO (ORCPT
        <rfc822;linux-acpi@vger.kernel.org>); Fri, 8 May 2020 15:11:14 -0400
Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133])
        by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2C5AC061A0C;
        Fri,  8 May 2020 12:11:14 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed;
        d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version
        :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:
        Content-Transfer-Encoding:Content-ID:Content-Description;
        bh=tUWbBKI5h7qcIWqn7V5B9OOroJpHaOkMQ99gt8+paWg=; b=ZFIdwDhlPQCBP+06Xc6FGc6o8R
        j4DJhPCH38rngf1Il0cTp/VUfH9Np0uLsnYfo0MGHwHFjmQyAvch8XUco4wEhUDgfDrulWKfm7+Y8
        xOyo+9JvgR/pioiJwmMKz6uTB92VX0IPpurv9wUvNpcHWJ0YXO9AOqYdWkGgm0G/K8QQvqdigrrSX
        c6eQ0hynD5RgDcm832/SyKns3BR3ugOKv9sbjDy13tg7Vr/hc8rAd8LrsD5WWUIEPsUhOXmLwZuAL
        vfoywGZ8lH8pQY55bkkXAQI3eCvfk5jVYrJ/CbTotVTJtQvLk9bb9NhVMlWBrpLuonmfu3eZEk0zP
        TI82M9Ng==;
Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net)
        by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux))
        id 1jX8OZ-0001Qe-1C; Fri, 08 May 2020 19:10:51 +0000
Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225])
        (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
        (Client did not present a certificate)
        by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 7FB2F301DFC;
        Fri,  8 May 2020 21:10:48 +0200 (CEST)
Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000)
        id 6AECD203CB697; Fri,  8 May 2020 21:10:48 +0200 (CEST)
Date:   Fri, 8 May 2020 21:10:48 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Joerg Roedel <joro@8bytes.org>
Cc:     x86@kernel.org, hpa@zytor.com,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>, rjw@rjwysocki.net,
        Arnd Bergmann <arnd@arndb.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Michal Hocko <mhocko@kernel.org>,
        Joerg Roedel <jroedel@suse.de>, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [RFC PATCH 2/7] mm/vmalloc: Track which page-table levels were
 modified
Message-ID: <20200508191048.GA2957@hirez.programming.kicks-ass.net>
References: <20200508144043.13893-1-joro@8bytes.org>
 <20200508144043.13893-3-joro@8bytes.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200508144043.13893-3-joro@8bytes.org>
Sender: linux-acpi-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-acpi.vger.kernel.org>
X-Mailing-List: linux-acpi@vger.kernel.org

On Fri, May 08, 2020 at 04:40:38PM +0200, Joerg Roedel wrote:

> +/*
> + * Architectures can set this mask to a combination of PGTBL_P?D_MODIFIED values
> + * and let generic vmalloc and ioremap code know when arch_sync_kernel_mappings()
> + * needs to be called.
> + */
> +#ifndef ARCH_PAGE_TABLE_SYNC_MASK
> +#define ARCH_PAGE_TABLE_SYNC_MASK 0
> +#endif
> +
> +void arch_sync_kernel_mappings(unsigned long start, unsigned long end);


> +	if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
> +		arch_sync_kernel_mappings(start, end);

So you're relying on the compiler DCE'ing the call in the 'normal' case.

Works I suppose, but I went over the patches twice to look for a default
implementation of it before I figured that out ...