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=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 2DFE9C64E7A for ; Tue, 1 Dec 2020 18:48:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E235208C3 for ; Tue, 1 Dec 2020 18:48:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="sTGMekwZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389368AbgLASs4 (ORCPT ); Tue, 1 Dec 2020 13:48:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726213AbgLASs4 (ORCPT ); Tue, 1 Dec 2020 13:48:56 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8BE8C0613CF for ; Tue, 1 Dec 2020 10:48:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=SnMmrOtdLjn+0REu5h4eicDcybAMDfdaQuxxnDjb/AY=; b=sTGMekwZa4oRmrkCGsEd4F80cO naAlmK95mZaAlDwjQYcpQOWbdGKxRl7cQtxp8V/t884CTdr8AKw1o4tFyVWApq/AhUWys1YwjQVq+ wXWI2PCYsi3dfS+i+hsvmoiJAEo7ikspon0TeglkHyw/QePJNaWUhIBAU1TovJwBb7Vad3Run31dO j7RgxQ3L5KdqAGZugSC1qGdE6L+XLWFELzoGba0gTWvB+KyvXJKCMsgwuYJ8kTyl0rZ5jXE51Ffzf jh3XDSyOtq0S2psZzPTlMBgWNOD7Pgjc/F7SnBs8MBq4t+/ANU4ShIE10m8G86ByarQUpk9lQ50iw nJvpeh5Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kkAh9-0008SG-B7; Tue, 01 Dec 2020 18:48:11 +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 B83C6300DAE; Tue, 1 Dec 2020 19:48:07 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id A1F69203ECD85; Tue, 1 Dec 2020 19:48:07 +0100 (CET) Date: Tue, 1 Dec 2020 19:48:07 +0100 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Christian Borntraeger , Linus Torvalds , Sven Schnelle , Thomas Gleixner , Linux Kernel Mailing List , the arch/x86 maintainers Subject: Re: [GIT pull] locking/urgent for v5.10-rc6 Message-ID: <20201201184807.GN3092@hirez.programming.kicks-ass.net> References: <20201130125211.GN2414@hirez.programming.kicks-ass.net> <20201130130315.GJ3092@hirez.programming.kicks-ass.net> <20201201080734.GQ2414@hirez.programming.kicks-ass.net> <20201201110724.GL3092@hirez.programming.kicks-ass.net> <20201201144644.GF1437@paulmck-ThinkPad-P72> <20201201145519.GY2414@hirez.programming.kicks-ass.net> <20201201181506.GM3092@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201201181506.GM3092@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 01, 2020 at 07:15:06PM +0100, Peter Zijlstra wrote: > On Tue, Dec 01, 2020 at 03:55:19PM +0100, Peter Zijlstra wrote: > > On Tue, Dec 01, 2020 at 06:46:44AM -0800, Paul E. McKenney wrote: > > > > > > So after having talked to Sven a bit, the thing that is happening, is > > > > that this is the one place where we take interrupts with RCU being > > > > disabled. Normally RCU is watching and all is well, except during idle. > > > > > > Isn't interrupt entry supposed to invoke rcu_irq_enter() at some point? > > > Or did this fall victim to recent optimizations? > > > > It does, but the problem is that s390 is still using > > I might've been too quick there, I can't actually seem to find where > s390 does rcu_irq_enter()/exit(). Argh, do_IRQ is per arch.. and that does irq_enter() which then does the deed (thanks Sven!).