From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org,
dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com,
fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com,
linux-api@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH v2 tip/core/rcu 01/22] smpboot: Add common code for notification from dying CPU
Date: Tue, 17 Mar 2015 15:08:46 +0100 [thread overview]
Message-ID: <20150317140846.GB23123@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20150317113648.GC3589@linux.vnet.ibm.com>
On Tue, Mar 17, 2015 at 04:36:48AM -0700, Paul E. McKenney wrote:
> On Tue, Mar 17, 2015 at 09:18:07AM +0100, Peter Zijlstra wrote:
> > On Mon, Mar 16, 2015 at 11:37:45AM -0700, Paul E. McKenney wrote:
> > > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> > >
> > > RCU ignores offlined CPUs, so they cannot safely run RCU read-side code.
> > > (They -can- use SRCU, but not RCU.) This means that any use of RCU
> > > during or after the call to arch_cpu_idle_dead(). Unfortunately,
> > > commit 2ed53c0d6cc99 added a complete() call, which will contain RCU
> > > read-side critical sections if there is a task waiting to be awakened.
> >
> > Got a little more detail there?
>
> Quite possibly. But exactly what sort of detail are you looking for?
What exact RCU usage you ran into that was problematic. It seems to
imply that calling complete() -- from a dead cpu -- which ends up in
try_to_wake_up() was the problem?
next prev parent reply other threads:[~2015-03-17 14:09 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20150316183743.GA21453@linux.vnet.ibm.com>
2015-03-16 18:37 ` [PATCH v2 tip/core/rcu 01/22] smpboot: Add common code for notification from dying CPU Paul E. McKenney
2015-03-16 18:37 ` Paul E. McKenney
[not found] ` <1426531086-23825-1-git-send-email-paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2015-03-17 8:18 ` Peter Zijlstra
2015-03-17 8:18 ` Peter Zijlstra
[not found] ` <20150317081807.GQ2896-IIpfhp3q70z/8w/KjCw3T+5/BudmfyzbbVWyRVo5IupeoWH0uzbU5w@public.gmane.org>
2015-03-17 11:36 ` Paul E. McKenney
2015-03-17 11:36 ` Paul E. McKenney
2015-03-17 14:08 ` Peter Zijlstra [this message]
2015-03-17 16:34 ` Paul E. McKenney
2015-03-17 16:56 ` Peter Zijlstra
[not found] ` <20150317165621.GF24151-ndre7Fmf5hadTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2015-03-17 17:32 ` Paul E. McKenney
2015-03-17 17:32 ` Paul E. McKenney
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