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;
Message-ID: <50aea6567bbdf89e03d50820c19cfb16bb764338.camel@redhat.com>
Subject: Re: [PATCH] powerpc/smp: Move rcu_cpu_starting() earlier
From:   Qian Cai <cai@redhat.com>
To:     paulmck@kernel.org, Michael Ellerman <mpe@ellerman.id.au>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Date:   Thu, 29 Oct 2020 09:48:36 -0400
In-Reply-To: <20201029003127.GJ3249@paulmck-ThinkPad-P72>
References: <20201028182334.13466-1-cai@redhat.com>
         <87lffpx598.fsf@mpe.ellerman.id.au>
         <20201029003127.GJ3249@paulmck-ThinkPad-P72>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Wed, 2020-10-28 at 17:31 -0700, Paul E. McKenney wrote:
> On Thu, Oct 29, 2020 at 11:09:07AM +1100, Michael Ellerman wrote:
> > Qian Cai <cai@redhat.com> writes:
> > > The call to rcu_cpu_starting() in start_secondary() is not early enough
> > > in the CPU-hotplug onlining process, which results in lockdep splats as
> > > follows:
> > 
> > Since when?
> > What kernel version?
> > 
> > I haven't seen this running CPU hotplug tests with PROVE_LOCKING=y on
> > v5.10-rc1. Am I missing a CONFIG?
> 
> My guess would be that adding CONFIG_PROVE_RAW_LOCK_NESTING=y will
> get you some splats.

Well, I don't have that set, so it should be CONFIG_PROVE_RCU_LIST=y. Anyway,
this is .config to reproduce on Power9 NV:

https://cailca.coding.net/public/linux/mm/git/files/master/powerpc.config