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=-7.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, 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 E5C48C4727C for ; Wed, 30 Sep 2020 19:22:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B82F20709 for ; Wed, 30 Sep 2020 19:22:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hpc/gT+d" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730232AbgI3TWu (ORCPT ); Wed, 30 Sep 2020 15:22:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725872AbgI3TWu (ORCPT ); Wed, 30 Sep 2020 15:22:50 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 27E4CC061755 for ; Wed, 30 Sep 2020 12:22:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=mzoge1vMkR/T6AFDq9SykRx8CLYszMD0V5SjriFX2to=; b=hpc/gT+dCMSkZkhWX8zQgqU5Il 8Eb4v6jC4PzAWq8ok9AOzpquAk5AtNfnSWk9fMOYyHTmxOrlJ4ZKZWeZdRL7/PmkLI2XBrSTD4zbe UtaRfns59571+PyoGGxxiW3r5elO1G9AWg9zQev4Y6W6zME2cAHYBz4A2eauW7v2Iaju4abOgkfCu YZ+VnOUP3DbxQ1MzRjzNSOXcrN9N2sBfYpCcrljG8e/tREeG4Kopevfwwej1cme5sSECYXLzRN29A QSCeujtfXa+0jof+ZkUMnrGws5hbGeuaoqZiir/AdHUgWd1aKPGkSNmpEST9Ne0pEXp3p09cTtV2A uutNCYIQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kNhgZ-000717-E4; Wed, 30 Sep 2020 19:22:43 +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 852933011F0; Wed, 30 Sep 2020 21:22:42 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 3F30C2011672D; Wed, 30 Sep 2020 21:22:42 +0200 (CEST) Date: Wed, 30 Sep 2020 21:22:42 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: Thomas Gleixner , "Paul E. McKenney" , LKML Subject: Re: [WARNING] kernel/rcu/tree.c:1058 rcu_irq_enter+0x15/0x20 Message-ID: <20200930192242.GM2611@hirez.programming.kicks-ass.net> References: <20200917131647.2b55ebb1@gandalf.local.home> <20200930181323.GF2628@hirez.programming.kicks-ass.net> <20200930151026.4a87ab79@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200930151026.4a87ab79@gandalf.local.home> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 30, 2020 at 03:10:26PM -0400, Steven Rostedt wrote: > On Wed, 30 Sep 2020 20:13:23 +0200 > Peter Zijlstra wrote: > > > diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h > > > index 6a584b3e5c74..3e5bc1dd71c6 100644 > > > --- a/include/linux/lockdep.h > > > +++ b/include/linux/lockdep.h > > > @@ -550,7 +550,8 @@ do { \ > > > > > > #define lockdep_assert_irqs_disabled() \ > > > do { \ > > > - WARN_ON_ONCE(debug_locks && raw_cpu_read(hardirqs_enabled)); \ > > > + WARN_ON_ONCE(debug_locks && raw_cpu_read(hardirqs_enabled) && \ > > > + likely(!(current->lockdep_recursion & LOCKDEP_RECURSION_MASK)));\ > > > } while (0) > > > > Blergh, IIRC there's header hell that way. The sane fix is killing off > > that trace_*_rcuidle() disease. > > Really? > > I could run this through all my other tests to see if that is the case. > That is, to see if it stumbles across header hell. I went through a lot of pain to make that per-cpu to avoid using current. But that might've been driven by lockdep_assert_preemption_disabled(), which is used in seqlock.h which in turn is included all over the place. That said, there's at least two things we can do: - make lockdep_recursion per-cpu too, IIRC we only ever set that when we have IRQs disabled anyway. OR - inspired by the above, as can save/clear - restore hardirqs_enabled when we frob lockdep_recursion. Admittedly, the second is somewhat gross :-)