From: peterz@infradead.org
To: Joel Fernandes <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, will@kernel.org,
npiggin@gmail.com, elver@google.com, jgross@suse.com,
paulmck@kernel.org, rostedt@goodmis.org, rjw@rjwysocki.net,
svens@linux.ibm.com, tglx@linutronix.de
Subject: Re: [PATCH v2 03/11] sched,idle,rcu: Push rcu_idle deeper into the idle path
Date: Thu, 27 Aug 2020 09:47:48 +0200 [thread overview]
Message-ID: <20200827074748.GY2674@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200827012419.GB1942571@google.com>
On Wed, Aug 26, 2020 at 09:24:19PM -0400, Joel Fernandes wrote:
> On Wed, Aug 26, 2020 at 09:18:26PM -0400, Joel Fernandes wrote:
> > On Fri, Aug 21, 2020 at 10:47:41AM +0200, Peter Zijlstra wrote:
> > > Lots of things take locks, due to a wee bug, rcu_lockdep didn't notice
> > > that the locking tracepoints were using RCU.
> > >
> > > Push rcu_idle_{enter,exit}() as deep as possible into the idle paths,
> > > this also resolves a lot of _rcuidle()/RCU_NONIDLE() usage.
> > >
> > > Specifically, sched_clock_idle_wakeup_event() will use ktime which
> > > will use seqlocks which will tickle lockdep, and
> > > stop_critical_timings() uses lock.
> >
> > I was wondering if those tracepoints should just use _rcuidle variant of the
> > trace call. But that's a terrible idea considering that would add unwanted
> > overhead I think.
> >
> > Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
>
> BTW, if tracepoint is converted to use RCU-trace flavor, then these kinds of
> issues go away, no? That RCU flavor is always watching.
All trace_*_rcuidle() and RCU_NONIDLE() usage is a bug IMO.
Ideally RCU-trace goes away too.
next prev parent reply other threads:[~2020-08-27 7:48 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 8:47 [PATCH v2 00/11] TRACE_IRQFLAGS wreckage Peter Zijlstra
2020-08-21 8:47 ` [PATCH v2 01/11] lockdep: Use raw_cpu_*() for per-cpu variables Peter Zijlstra
2020-08-27 1:05 ` Joel Fernandes
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-08-21 8:47 ` [PATCH v2 02/11] cpuidle: Fixup IRQ state Peter Zijlstra
2020-08-21 17:36 ` Rafael J. Wysocki
2020-08-27 1:06 ` Joel Fernandes
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-08-21 8:47 ` [PATCH v2 03/11] sched,idle,rcu: Push rcu_idle deeper into the idle path Peter Zijlstra
2020-08-27 1:18 ` Joel Fernandes
2020-08-27 1:24 ` Joel Fernandes
2020-08-27 7:47 ` peterz [this message]
2020-08-27 7:53 ` Thomas Gleixner
2020-08-27 22:30 ` Joel Fernandes
2020-09-02 7:08 ` peterz
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-08-21 8:47 ` [PATCH v2 04/11] cpuidle: Make CPUIDLE_FLAG_TLB_FLUSHED generic Peter Zijlstra
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-08-21 8:47 ` [PATCH v2 05/11] cpuidle: Move trace_cpu_idle() into generic code Peter Zijlstra
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-08-21 8:47 ` [PATCH v2 06/11] x86/entry: Remove unused THUNKs Peter Zijlstra
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-08-21 8:47 ` [PATCH v2 07/11] locking/lockdep: Cleanup Peter Zijlstra
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-08-21 8:47 ` [PATCH v2 08/11] nds32: Implement arch_irqs_disabled() Peter Zijlstra
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-08-21 8:47 ` [PATCH v2 09/11] arm64: " Peter Zijlstra
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-08-21 8:47 ` [PATCH v2 10/11] lockdep: Only trace IRQ edges Peter Zijlstra
2020-08-26 0:47 ` Thomas Gleixner
2020-09-02 4:21 ` Guenter Roeck
2020-09-02 9:09 ` peterz
2020-09-02 9:12 ` peterz
2020-09-02 13:48 ` Guenter Roeck
2020-09-08 14:22 ` peterz
2020-09-08 14:40 ` Guenter Roeck
2020-09-08 15:41 ` [PATCH] sparc64: Fix irqtrace warnings on Ultra-S peterz
2020-08-21 8:47 ` [PATCH v2 11/11] lockdep,trace: Expose tracepoints Peter Zijlstra
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-09-02 3:51 ` [PATCH v2 11/11] " Guenter Roeck
2020-09-02 7:24 ` peterz
2020-09-02 13:21 ` Guenter Roeck
2020-09-02 8:56 ` peterz
2020-09-02 13:57 ` Guenter Roeck
2020-09-03 14:00 ` peterz
2020-09-03 14:13 ` peterz
2020-09-03 15:19 ` Guenter Roeck
2020-09-03 15:36 ` peterz
2020-09-03 15:54 ` Paul E. McKenney
2020-09-03 18:11 ` Guenter Roeck
2020-08-21 12:58 ` [PATCH v2 00/11] TRACE_IRQFLAGS wreckage peterz
2020-08-26 10:16 ` [PATCH v2 12/11] mips: Implement arch_irqs_disabled() peterz
2020-08-27 7:54 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
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