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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B4372C4360C for ; Fri, 27 Sep 2019 08:11:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D3BA2146E for ; Fri, 27 Sep 2019 08:11:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727221AbfI0ILm (ORCPT ); Fri, 27 Sep 2019 04:11:42 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:45285 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726942AbfI0ILF (ORCPT ); Fri, 27 Sep 2019 04:11:05 -0400 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iDlKx-0005cn-3h; Fri, 27 Sep 2019 10:10:47 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id A547C1C0742; Fri, 27 Sep 2019 10:10:43 +0200 (CEST) Date: Fri, 27 Sep 2019 08:10:43 -0000 From: "tip-bot2 for Mathieu Desnoyers" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/urgent] sched/membarrier: Call sync_core only before usermode for same mm Cc: Oleg Nesterov , Mathieu Desnoyers , "Peter Zijlstra (Intel)" , Chris Metcalf , Christoph Lameter , "Eric W. Biederman" , Kirill Tkhai , Linus Torvalds , Mike Galbraith , "Paul E. McKenney" , "Russell King - ARM Linux admin" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , linux-kernel@vger.kernel.org In-Reply-To: <20190919173705.2181-4-mathieu.desnoyers@efficios.com> References: <20190919173705.2181-4-mathieu.desnoyers@efficios.com> MIME-Version: 1.0 Message-ID: <156957184362.9866.4020605846698676491.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/urgent branch of tip: Commit-ID: 2840cf02fae627860156737e83326df354ee4ec6 Gitweb: https://git.kernel.org/tip/2840cf02fae627860156737e83326df354ee4ec6 Author: Mathieu Desnoyers AuthorDate: Thu, 19 Sep 2019 13:37:01 -04:00 Committer: Ingo Molnar CommitterDate: Wed, 25 Sep 2019 17:42:30 +02:00 sched/membarrier: Call sync_core only before usermode for same mm When the prev and next task's mm change, switch_mm() provides the core serializing guarantees before returning to usermode. The only case where an explicit core serialization is needed is when the scheduler keeps the same mm for prev and next. Suggested-by: Oleg Nesterov Signed-off-by: Mathieu Desnoyers Signed-off-by: Peter Zijlstra (Intel) Cc: Chris Metcalf Cc: Christoph Lameter Cc: Eric W. Biederman Cc: Kirill Tkhai Cc: Linus Torvalds Cc: Mike Galbraith Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Russell King - ARM Linux admin Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20190919173705.2181-4-mathieu.desnoyers@efficios.com Signed-off-by: Ingo Molnar --- include/linux/sched/mm.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index 4a79440..8557ec6 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -362,6 +362,8 @@ enum { static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm) { + if (current->mm != mm) + return; if (likely(!(atomic_read(&mm->membarrier_state) & MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE))) return;