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=-0.8 required=3.0 tests=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 86F85C433DF for ; Fri, 12 Jun 2020 09:01:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 512DE20801 for ; Fri, 12 Jun 2020 09:01:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726398AbgFLJBZ (ORCPT ); Fri, 12 Jun 2020 05:01:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726319AbgFLJBZ (ORCPT ); Fri, 12 Jun 2020 05:01:25 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8C61C08C5C1 for ; Fri, 12 Jun 2020 02:01:24 -0700 (PDT) Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jjfYc-0000VY-SN; Fri, 12 Jun 2020 11:01:02 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id DD984100F5A; Fri, 12 Jun 2020 11:01:01 +0200 (CEST) From: Thomas Gleixner To: Andy Lutomirski , Andy Lutomirski Cc: Peter Zijlstra , Naresh Kamboju , open list , X86 ML , cj.chengjian@huawei.com, Arnaldo Carvalho de Melo , Ingo Molnar , "H. Peter Anvin" , Borislav Petkov , Minchan Kim , Andrew Morton , Michel Lespinasse , lkft-triage@lists.linaro.org, Dave Hansen Subject: Re: Perf: WARNING: arch/x86/entry/common.c:624 idtentry_exit_cond_rcu+0x92/0xc0 In-Reply-To: References: <20200611192518.GA2483@worktop.programming.kicks-ass.net> Date: Fri, 12 Jun 2020 11:01:01 +0200 Message-ID: <87imfwd5f6.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain 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 Andy Lutomirski writes: > On Thu, Jun 11, 2020 at 4:22 PM Andy Lutomirski wrote: > > Two bugs here. > > 1. We had an issue with WARN. Patch sent. Grabbed it > 2. idtentry.h has, for x86_32: > > # define DEFINE_IDTENTRY_IST DEFINE_IDTENTRY > > This is nonsense. It's getting late over here and I'd rather focus on > the more interesting RCU issue, so that's all from me today. Well, this might be nonsense, but it's exactly matching the current code in mainline which, e.g. for #DB does: SYM_CODE_START(debug) /* * Entry from sysenter is now handled in common_exception */ ASM_CLAC pushl $0 pushl $do_debug jmp common_exception SYM_CODE_END(debug) There is no IST on 32bit, never was. We do software stack switching for device interrupts, but that's a different story. Thanks, tglx