From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Petr Mladek <pmladek@suse.com>,
Vince Weaver <vincent.weaver@maine.edu>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
"dvyukov@google.com" <dvyukov@google.com>
Subject: Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start
Date: Thu, 1 Dec 2016 17:41:07 +0100 [thread overview]
Message-ID: <20161201164107.GN3092@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20161201123316.GZ3924@linux.vnet.ibm.com>
On Thu, Dec 01, 2016 at 04:33:16AM -0800, Paul E. McKenney wrote:
> On Thu, Dec 01, 2016 at 06:52:35AM +0100, Peter Zijlstra wrote:
> > On Wed, Nov 30, 2016 at 01:13:03PM -0600, Josh Poimboeuf wrote:
> > > This question was probably intended for other folks, but I should point
> > > out that idle tasks *do* invoke the scheduler. cpu_idle_loop() calls
> > > schedule_preempt_disabled().
> >
> > Right, but that doesn't matter I think. The below will simply not call
> > rcu_note_voluntary_context_switch() from the idle task, which would be
> > fine I think.
> >
> > > > So is the following a sensible approach, or should I look elsewhere?
> > > >
> > > > #define cond_resched_rcu_qs() \
> > > > do { \
> > > > if (!is_idle_task(current) && !cond_resched()) \
> > > > rcu_note_voluntary_context_switch(current); \
> >
> > You should reverse your conditions though:
> >
> > if (!cond_resched() && !is_idle_task(current))
> > rcu_note_voluntary_context_switch(current);
> >
> > That way we'll still do cond_resched() and you only gate the RCU call.
>
> This makes it illegal at early boot.
Humm, how early are we talking?
next prev parent reply other threads:[~2016-12-01 16:41 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-24 17:33 perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Vince Weaver
2016-11-28 21:54 ` Josh Poimboeuf
2016-11-29 0:40 ` Paul E. McKenney
2016-11-29 5:52 ` Josh Poimboeuf
2016-11-29 9:16 ` Peter Zijlstra
2016-11-29 14:07 ` Paul E. McKenney
2016-11-29 15:09 ` Josh Poimboeuf
2016-11-29 16:12 ` Petr Mladek
2016-11-29 18:01 ` Paul E. McKenney
2016-11-29 16:51 ` Paul E. McKenney
2016-11-29 17:17 ` Josh Poimboeuf
2016-11-29 17:36 ` Paul E. McKenney
2016-11-30 9:29 ` Petr Mladek
2016-11-29 10:28 ` Paul E. McKenney
2016-11-29 12:43 ` Peter Zijlstra
2016-11-29 15:10 ` Paul E. McKenney
2016-11-29 16:29 ` Petr Mladek
2016-11-29 17:10 ` Peter Zijlstra
2016-11-29 19:39 ` Paul E. McKenney
2016-11-29 19:52 ` Peter Zijlstra
2016-11-29 20:07 ` Paul E. McKenney
2016-11-29 20:32 ` Paul E. McKenney
2016-11-30 19:13 ` Josh Poimboeuf
2016-11-30 19:49 ` Paul E. McKenney
2016-12-01 5:52 ` Peter Zijlstra
2016-12-01 12:33 ` Paul E. McKenney
2016-12-01 16:41 ` Peter Zijlstra [this message]
2016-12-01 17:00 ` Paul E. McKenney
2016-11-30 10:01 ` Petr Mladek
2016-11-30 11:06 ` Peter Zijlstra
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