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[71.184.117.43]) by smtp.gmail.com with ESMTPSA id q5sm2277936qkf.14.2020.01.23.20.21.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 Jan 2020 20:21:36 -0800 (PST) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Qian Cai 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: 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 X-Mailer: iPhone Mail (17C54) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On Jan 21, 2020, at 5:35 AM, Peter Zijlstra 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?=