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=-5.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 56AB2C433E0 for ; Sat, 13 Jun 2020 19:19:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3CC3F2078A for ; Sat, 13 Jun 2020 19:19:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726378AbgFMTTc (ORCPT ); Sat, 13 Jun 2020 15:19:32 -0400 Received: from cloudserver094114.home.pl ([79.96.170.134]:46790 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726323AbgFMTTc (ORCPT ); Sat, 13 Jun 2020 15:19:32 -0400 Received: from 89-77-60-66.dynamic.chello.pl (89.77.60.66) (HELO kreacher.localnet) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.415) id b5415c95c99b9eab; Sat, 13 Jun 2020 21:19:29 +0200 From: "Rafael J. Wysocki" To: "Rafael J. Wysocki" Cc: Dan Williams , Erik Kaneda , rafael.j.wysocki@intel.com, Len Brown , Borislav Petkov , Ira Weiny , James Morse , Myron Stowe , Andy Shevchenko , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-nvdimm@lists.01.org, Bob Moore Subject: Re: [RFT][PATCH 0/3] ACPI: ACPICA / OSL: Avoid unmapping ACPI memory inside of the AML interpreter Date: Sat, 13 Jun 2020 21:19:28 +0200 Message-ID: <6131168.ASH3qCSnW2@kreacher> In-Reply-To: <318372766.6LKUBsbRXE@kreacher> References: <158889473309.2292982.18007035454673387731.stgit@dwillia2-desk3.amr.corp.intel.com> <318372766.6LKUBsbRXE@kreacher> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Wednesday, June 10, 2020 2:17:04 PM CEST Rafael J. Wysocki wrote: > Hi All, > > This series is to address the problem with RCU synchronization occurring, > possibly relatively often, inside of acpi_ex_system_memory_space_handler(), > when the namespace and interpreter mutexes are held. > > The basic idea is to avoid the actual unmapping of memory in > acpi_ex_system_memory_space_handler() by making it take the advantage of the > reference counting of memory mappings utilized by the OSL layer in Linux. > > The basic assumption in patch [1/3] is that if the special > ACPI_OS_MAP_MEMORY_FAST_PATH() macro is present, it can be used to increment > the reference counter of a known-existing memory mapping in the OS layer > which then is dropped by the subsequent acpi_os_unmap_memory() without > unmapping the address range at hand. That can be utilized by > acpi_ex_system_memory_space_handler() to prevent the reference counters of > all mappings used by it from dropping down to 0 (which also prevents the > address ranges associated with them from being unmapped) so that they can > be unmapped later (specifically, at the operation region deactivation time). > > Patch [2/3] defers the unmapping even further, until the namespace and > interpreter mutexes are released, to avoid invoking the RCU synchronization > under theses mutexes. > > Finally, patch [3/3] changes the OS layer in Linux to provide the > ACPI_OS_MAP_MEMORY_FAST_PATH() macro. > > Note that if this macro is not defined, the code works the way it used to. > > The series is available from the git branch at > > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \ > acpica-osl > > for easier testing. Please disregard this patch series, it will be replaced by a new one which already is there in the acpica-osl branch above. Thanks!