From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>, Qian Cai <cai@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>, x86 <x86@kernel.org>,
linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
Linux Next Mailing List <linux-next@vger.kernel.org>,
Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [tip: locking/core] lockdep: Fix lockdep recursion
Date: Wed, 14 Oct 2020 23:53:19 +0200 [thread overview]
Message-ID: <20201014215319.GF2974@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20201014183405.GA27666@paulmck-ThinkPad-P72>
On Wed, Oct 14, 2020 at 11:34:05AM -0700, Paul E. McKenney wrote:
> commit 7deaa04b02298001426730ed0e6214ac20d1a1c1
> Author: Paul E. McKenney <paulmck@kernel.org>
> Date: Tue Oct 13 12:39:23 2020 -0700
>
> rcu: Prevent lockdep-RCU splats on lock acquisition/release
>
> The rcu_cpu_starting() and rcu_report_dead() functions transition the
> current CPU between online and offline state from an RCU perspective.
> Unfortunately, this means that the rcu_cpu_starting() function's lock
> acquisition and the rcu_report_dead() function's lock releases happen
> while the CPU is offline from an RCU perspective, which can result in
> lockdep-RCU splats about using RCU from an offline CPU. In reality,
> aside from the splats, both transitions are safe because a new grace
> period cannot start until these functions release their locks.
But we call the trace_* crud before we acquire the lock. Are you sure
that's a false-positive?
next prev parent reply other threads:[~2020-10-15 1:30 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-09 7:58 [tip: locking/core] lockdep: Fix lockdep recursion tip-bot2 for Peter Zijlstra
2020-10-09 13:41 ` Qian Cai
2020-10-09 13:58 ` Paul E. McKenney
2020-10-09 15:30 ` Qian Cai
2020-10-09 16:11 ` Paul E. McKenney
2020-10-09 16:23 ` Peter Zijlstra
2020-10-09 16:37 ` Paul E. McKenney
2020-10-09 17:36 ` Qian Cai
2020-10-09 17:50 ` Paul E. McKenney
2020-10-09 17:54 ` Qian Cai
2020-10-09 18:21 ` Paul E. McKenney
2020-10-12 3:11 ` Boqun Feng
2020-10-12 14:14 ` Qian Cai
2020-10-12 21:28 ` Paul E. McKenney
2020-10-13 10:34 ` Peter Zijlstra
2020-10-13 10:44 ` Peter Zijlstra
2020-10-13 11:25 ` Peter Zijlstra
2020-10-13 16:26 ` Paul E. McKenney
2020-10-13 19:30 ` Paul E. McKenney
2020-10-14 18:34 ` Paul E. McKenney
2020-10-14 21:53 ` Peter Zijlstra [this message]
2020-10-14 22:11 ` Paul E. McKenney
2020-10-14 22:39 ` Peter Zijlstra
2020-10-14 23:55 ` Paul E. McKenney
2020-10-15 3:41 ` Paul E. McKenney
2020-10-15 9:49 ` Peter Zijlstra
2020-10-15 9:50 ` Peter Zijlstra
2020-10-15 16:15 ` Paul E. McKenney
2020-10-15 9:52 ` Peter Zijlstra
2020-10-15 16:20 ` Paul E. McKenney
2020-10-15 16:15 ` Paul E. McKenney
2020-10-15 17:23 ` Paul E. McKenney
2020-10-13 16:15 ` Paul E. McKenney
2020-10-13 10:27 ` Peter Zijlstra
2020-10-13 16:24 ` Boqun Feng
2020-10-27 19:31 ` Qian Cai
2020-10-28 3:01 ` Paul E. McKenney
2020-10-28 14:39 ` Qian Cai
2020-10-28 15:53 ` Paul E. McKenney
2020-10-28 20:08 ` Qian Cai
2020-10-28 21:02 ` Paul E. McKenney
-- strict thread matches above, loose matches on Subject: below --
2020-10-07 16:20 tip-bot2 for Peter Zijlstra
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