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[23.128.96.18]) by mx.google.com with ESMTP id g7si591632edu.307.2020.10.28.15.11.00; Wed, 28 Oct 2020 15:11:22 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b="VZS/5aq5"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730343AbgJ1WJ3 (ORCPT + 99 others); Wed, 28 Oct 2020 18:09:29 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:29836 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730335AbgJ1WJ1 (ORCPT ); Wed, 28 Oct 2020 18:09:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603922965; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=284b5r+7PQhFjN0PmG3IKEcminvVA7d407HnU3mjfkE=; b=VZS/5aq5iT7jByT+bagzx8vzPqQHXTY2ClAhq/IA8csEDMZG/rIpbmtlM2xM9TFENNtDM3 hf7B6pwDwmZfoqlZUlft9lP2h9HW6NPeWSbTYO1Bkxqt9AEfo5/VTq3n7LM2/wNPE/Mu3e yz/HloZna19HQFNiC6Kk7/H0/o+8U9k= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-416-KC48yM7BOjKGJFAyziTMpw-1; Wed, 28 Oct 2020 16:09:03 -0400 X-MC-Unique: KC48yM7BOjKGJFAyziTMpw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8ECDB8030DE; Wed, 28 Oct 2020 20:09:01 +0000 (UTC) Received: from ovpn-66-92.rdu2.redhat.com (ovpn-66-92.rdu2.redhat.com [10.10.66.92]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4472D5B4B6; Wed, 28 Oct 2020 20:09:00 +0000 (UTC) Message-ID: <7cd579ccdacb4f672cf2dc3a0d4553d1845e7ebf.camel@redhat.com> Subject: Re: [tip: locking/core] lockdep: Fix lockdep recursion From: Qian Cai To: paulmck@kernel.org Cc: Boqun Feng , "Peter Zijlstra (Intel)" , Steven Rostedt , Ingo Molnar , x86 , linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, Linux Next Mailing List , Stephen Rothwell Date: Wed, 28 Oct 2020 16:08:59 -0400 In-Reply-To: <20201028155328.GC3249@paulmck-ThinkPad-P72> References: <160223032121.7002.1269740091547117869.tip-bot2@tip-bot2> <20201012031110.GA39540@debian-boqun.qqnc3lrjykvubdpftowmye0fmh.lx.internal.cloudapp.net> <1db80eb9676124836809421e85e1aa782c269a80.camel@redhat.com> <20201028030130.GB3249@paulmck-ThinkPad-P72> <8194dca3b2e871f04c7f6e49672837f8df22546f.camel@redhat.com> <20201028155328.GC3249@paulmck-ThinkPad-P72> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2020-10-28 at 08:53 -0700, Paul E. McKenney wrote: > On Wed, Oct 28, 2020 at 10:39:47AM -0400, Qian Cai wrote: > > On Tue, 2020-10-27 at 20:01 -0700, Paul E. McKenney wrote: > > > If I have the right email thread associated with the right fixes, these > > > commits in -rcu should be what you are looking for: > > > > > > 73b658b6b7d5 ("rcu: Prevent lockdep-RCU splats on lock > > > acquisition/release") > > > 626b79aa935a ("x86/smpboot: Move rcu_cpu_starting() earlier") > > > > > > And maybe this one as well: > > > > > > 3a6f638cb95b ("rcu,ftrace: Fix ftrace recursion") > > > > > > Please let me know if these commits do not fix things. > > While those patches silence the warnings for x86. Other arches are still > > suffering. It is only after applying the patch from Boqun below fixed > > everything. > > Fair point! > > > Is it a good idea for Boqun to write a formal patch or we should fix all > > arches > > individually like "x86/smpboot: Move rcu_cpu_starting() earlier"? > > By Boqun's patch, you mean the change to debug_lockdep_rcu_enabled() > shown below? Peter Zijlstra showed that real failures can happen, so we Yes. > do not want to cover them up. So we are firmly in "fix all architectures" > space here, sorry! > > I am happy to accumulate those patches, but cannot commit to creating > or testing them. Okay, I posted 3 patches for each arch and CC'ed you. BTW, it looks like something is wrong on @vger.kernel.org today where I received many of those, 4.7.1 Hello [216.205.24.124], for recipient address the policy analysis reported: zpostgrey: connect: Connection refused and I can see your previous mails did not even reach there either. https://lore.kernel.org/lkml/