Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
From:   Qian Cai <cai@lca.pw>
Mime-Version: 1.0 (1.0)
Subject: Re: [PATCH v2] sched/core: fix illegal RCU from offline CPUs
Date:   Thu, 23 Jan 2020 23:21:35 -0500
Message-Id: <A72A7F42-A166-4403-B12C-32B2D7A662C4@lca.pw>
References: <20200121103506.GH14914@hirez.programming.kicks-ass.net>
Cc:     mingo@redhat.com, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        paulmck@kernel.org, tglx@linutronix.de, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
In-Reply-To: <20200121103506.GH14914@hirez.programming.kicks-ass.net>
To:     Peter Zijlstra <peterz@infradead.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> On Jan 21, 2020, at 5:35 AM, Peter Zijlstra <peterz@infradead.org> wrote:
>=20
> Something like this; except you'll need to go audit archs to make sure
> they all call idle_task_exit() and/or put in comments on why they don't
> have to (perhaps their bringup switches them to &init_mm unconditionally
> and the switch_mm() is not required).

Damn, I am having a hard time to motivate myself to learn all about those tw=
o =E2=80=9Cdead=E2=80=9C arches from scratch. I suppose the first step we co=
uld put a dummy finish_cpu() for alpha and parisc if they don=E2=80=99t call=
 idle_task_exit() in the first place anyway, so if it is a bug there it is a=
nother issue that could be dealt with in a separate patch later?=