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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 AC596C433E0 for ; Sun, 26 Jul 2020 11:59:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 79DA620714 for ; Sun, 26 Jul 2020 11:59:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ismlg70E" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726669AbgGZL7z (ORCPT ); Sun, 26 Jul 2020 07:59:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47322 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725848AbgGZL7z (ORCPT ); Sun, 26 Jul 2020 07:59:55 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39B39C0619D2; Sun, 26 Jul 2020 04:59:55 -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=3Ulcv+XYXDsbe/gQ1QFaymA76fUaf73Ogbakhyf58ME=; b=ismlg70EGIrI2GcxeAyrDWqIpb ERntESs/K7v8oLSLDAyAEvckbFbKb5gDNBysO72uyFZ8Iv9LllqLYbcQq7cYbMNeZdfgEeofsaEr0 dOMiZHBiYdzAXlTvErQKqCJLbaJAYj42ZODd6CzzYbBFv1kovJA8FMzXYXQ9RdAh7is1fK6Tj8WYz gIWoY29VXIgaLtBs88qi1Dn1cJYY6dLu93ubtTpChQWEwu7+zMp2SHol91o/Op4GE2ng0AvfW4ozw csLZIUPXqGeS6rK4DmgbMKFKvLwqTQIBR6PCvlLCMET4DGwcyC6C4zs8Id+3T+qrwgXJEv98xYrLZ nFHyab/g==; 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 1jzfJj-0006ih-6B; Sun, 26 Jul 2020 11:59:47 +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 E7704304D58; Sun, 26 Jul 2020 13:59:44 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 33A6D284D5CC2; Sun, 26 Jul 2020 13:59:44 +0200 (CEST) Date: Sun, 26 Jul 2020 13:59:44 +0200 From: peterz@infradead.org To: Nicholas Piggin Cc: Alexey Kardashevskiy , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ingo Molnar , Will Deacon Subject: Re: [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled synchronisation with actual irq state Message-ID: <20200726115944.GB119549@hirez.programming.kicks-ass.net> References: <20200723105615.1268126-1-npiggin@gmail.com> <20200725202617.GI10769@hirez.programming.kicks-ass.net> <1595735694.b784cvipam.astroid@bobo.none> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1595735694.b784cvipam.astroid@bobo.none> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jul 26, 2020 at 02:14:34PM +1000, Nicholas Piggin wrote: > > Now, x86, and at least arm64 call nmi_enter() before > > trace_hardirqs_off(), but AFAICT Power never did that, and that's part > > of the problem. nmi_enter() does lockdep_off() and that _used_ to also > > kill IRQ tracking. > > Power does do nmi_enter -- __perf_event_interrupt() > > nmi = perf_intr_is_nmi(regs); > if (nmi) > nmi_enter(); > else > irq_enter(); That's _waaaay_ too late, you've done the trace_hardirqs_{off,on} in arch/powerpc/kernel/exceptions-64e.S, you need to _first_ do nmi_enter() and _then_ trace_hardirqs_off(), or rather, that's still broken, but then we get into the details of entry ordering.