All of lore.kernel.org
 help / color / mirror / Atom feed
From: Steven Rostedt <rostedt@goodmis.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: Possible use of RCU while in extended QS: idle vs RCU read-side in interrupt vs rcu_eqs_exit
Date: Thu, 10 Jan 2019 11:08:39 -0500	[thread overview]
Message-ID: <20190110110839.7daeef3d@gandalf.local.home> (raw)
In-Reply-To: <2103471967.794.1547084331086.JavaMail.zimbra@efficios.com>

On Wed, 9 Jan 2019 20:38:51 -0500 (EST)
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:

> Hi Paul,
> 
> I've had a user report that trace_sched_waking() appears to be
> invoked while !rcu_is_watching() in some situation, so I started
> digging into the scheduler idle code.

I'm wondering if this isn't a bug. Do you have the backtrace for where
trace_sched_waking() was called without rcu watching?

-- Steve

> 
> It appears that interrupts are re-enabled before rcu_eqs_exit() is
> invoked when exiting idle code from the scheduler.
> 
> I wonder what happens if an interrupt handler (including scheduler code)
> happens to issue a RCU read-side critical section before rcu_eqs_exit()
> is called ? Is there some code on interrupt entry that ensures rcu eqs
> state is exited in such scenario ?
> 
> Thanks,
> 
> Mathieu
> 


  parent reply	other threads:[~2019-01-10 16:08 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-10  1:38 Possible use of RCU while in extended QS: idle vs RCU read-side in interrupt vs rcu_eqs_exit Mathieu Desnoyers
2019-01-10  4:13 ` Paul E. McKenney
2019-01-10  6:30   ` Mathieu Desnoyers
2019-01-10 14:19     ` Paul E. McKenney
2019-01-10 16:08 ` Steven Rostedt [this message]
2019-01-10 16:44   ` Mathieu Desnoyers
2019-01-10 17:11     ` Mathieu Desnoyers
2019-01-10 17:23       ` Steven Rostedt
2019-01-10 17:25       ` Mathieu Desnoyers
2019-01-10 17:45         ` Perf: event wakeup discards sched_waking events Mathieu Desnoyers
2019-01-14 13:09           ` Peter Zijlstra
2019-01-14 21:36             ` Mathieu Desnoyers
2019-01-14 22:04               ` Steven Rostedt
2019-01-14 22:31                 ` Mathieu Desnoyers

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190110110839.7daeef3d@gandalf.local.home \
    --to=rostedt@goodmis.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=peterz@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.