From: Mark Rutland <mark.rutland@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: juri.lelli@redhat.com, daniel.lezcano@linaro.org,
wanpengli@tencent.com, kvm@vger.kernel.org, rafael@kernel.org,
pv-drivers@vmware.com, dave.hansen@linux.intel.com,
virtualization@lists.linux-foundation.org, bsegall@google.com,
amakhalov@vmware.com, will@kernel.org, vschneid@redhat.com,
hpa@zytor.com, x86@kernel.org, mingo@kernel.org, mgorman@suse.de,
linux-trace-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
boqun.feng@gmail.com, Steven Rostedt <rostedt@goodmis.org>,
bp@alien8.de, vincent.guittot@linaro.org,
boris.ostrovsky@oracle.com, dietmar.eggemann@arm.com,
jgross@suse.com, seanjc@google.com, linux-kernel@vger.kernel.org,
tglx@linutronix.de, mhiramat@kernel.org, pbonzini@redhat.com,
bristot@redhat.com
Subject: Re: [PATCH 3/6] ftrace/x86: Warn and ignore graph tracing when RCU is disabled
Date: Tue, 24 Jan 2023 17:12:14 +0000 [thread overview]
Message-ID: <Y9ARbgtYhxSuOIlZ@FVFF77S0Q05N> (raw)
In-Reply-To: <Y8/u00WHGElMDjoo@hirez.programming.kicks-ass.net>
On Tue, Jan 24, 2023 at 03:44:35PM +0100, Peter Zijlstra wrote:
> On Mon, Jan 23, 2023 at 05:07:53PM -0500, Steven Rostedt wrote:
>
> > Actually, perhaps we can just add this, and all you need to do is create
> > and set CONFIG_NO_RCU_TRACING (or some other name).
>
> Elsewhere I've used CONFIG_ARCH_WANTS_NO_INSTR for this.
Yes please; if we use CONFIG_ARCH_WANTS_NO_INSTR then arm64 will get this "for
free" once we add the missing checks (which I assume we need) in our ftrace_prepare_return().
> Anyway, I took it for a spin and it .... doesn't seems to do the job.
>
> With my patch the first splat is
>
> "RCU not on for: cpuidle_poll_time+0x0/0x70"
>
> While with yours I seems to get the endless:
>
> "WARNING: suspicious RCU usage"
>
> thing. Let me see if I can figure out where it goes side-ways.
Hmmm... for WARN_ONCE() don't we need to wake RCU first also? I thought we
needed that at least for the printk machinery?
Thanks,
Mark.
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next prev parent reply other threads:[~2023-01-24 17:12 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-23 20:50 [PATCH 0/6] A few cpuidle vs rcu fixes Peter Zijlstra
2023-01-23 20:50 ` [PATCH 1/6] x86: Always inline arch_atomic64 Peter Zijlstra
2023-01-23 20:50 ` [PATCH 2/6] x86/pvclock: improve atomic update of last_value in pvclock_clocksource_read Peter Zijlstra
2023-01-23 20:50 ` [PATCH 3/6] ftrace/x86: Warn and ignore graph tracing when RCU is disabled Peter Zijlstra
2023-01-23 21:53 ` Steven Rostedt
2023-01-23 22:07 ` Steven Rostedt
2023-01-24 14:44 ` Peter Zijlstra
2023-01-24 17:12 ` Mark Rutland [this message]
2023-01-25 9:37 ` Peter Zijlstra
2023-01-25 10:47 ` Peter Zijlstra
2023-01-25 11:32 ` Mark Rutland
[not found] ` <20230125184658.GL2948950@paulmck-ThinkPad-P17-Gen-1>
2023-01-26 9:28 ` Peter Zijlstra
2023-01-23 20:50 ` [PATCH 4/6] x86: Mark sched_clock() noinstr Peter Zijlstra
2023-01-23 20:50 ` [PATCH 5/6] sched/clock: Make local_clock() noinstr Peter Zijlstra
2023-01-23 20:50 ` [PATCH 6/6] cpuidle: Fix poll_idle() noinstr annotation Peter Zijlstra
2023-01-24 14:24 ` Rafael J. Wysocki
2023-01-24 16:34 ` [PATCH 0/6] A few cpuidle vs rcu fixes Mark Rutland
2023-01-24 17:30 ` Mark Rutland
2023-01-24 18:39 ` Mark Rutland
2023-01-25 9:35 ` Peter Zijlstra
2023-01-25 9:40 ` Peter Zijlstra
2023-01-25 10:23 ` Mark Rutland
2023-01-25 9:31 ` Peter Zijlstra
2023-01-25 9:36 ` Mark Rutland
2023-01-25 15:20 ` Mark Rutland
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