From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Sasha Levin <sasha.levin@oracle.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: timers: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
Date: Sat, 30 Jan 2016 16:28:25 -0800 [thread overview]
Message-ID: <20160131002825.GJ6719@linux.vnet.ibm.com> (raw)
In-Reply-To: <20160129152735.GB407@worktop>
On Fri, Jan 29, 2016 at 04:27:35PM +0100, Peter Zijlstra wrote:
> On Fri, Jan 15, 2016 at 03:14:10PM -0800, Paul E. McKenney wrote:
> > And if I make the scheduling-clock interrupt send extra wakeups to the RCU
> > grace-period kthread when needed, things work even with CPU hotplug going.
> >
> > The "when needed" means any time that the RCU grace-period kthread has
> > been sleeping three times as long as the timeout interval. If the first
> > wakeup does nothing, it does another wakeup once per second.
> >
> > So it looks like this change makes an existing problem much worse, as
> > opposed to introducing a new problem.
>
> I have a vague idea about a possible race window. Have you been
> observing this on PPC or x86?
>
> The reason I'm asking is that PPC (obviously) allows for more races :-)
;-)
I have been seeing this on x86.
Thanx, Paul
prev parent reply other threads:[~2016-01-31 0:28 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-12 20:03 timers: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected Sasha Levin
2016-01-12 20:18 ` Peter Zijlstra
2016-01-12 20:52 ` Paul E. McKenney
2016-01-13 9:05 ` Thomas Gleixner
2016-01-13 16:16 ` Paul E. McKenney
2016-01-14 17:43 ` Thomas Gleixner
2016-01-14 18:18 ` Paul E. McKenney
2016-01-14 19:47 ` Thomas Gleixner
2016-01-15 1:42 ` Paul E. McKenney
2016-01-15 10:03 ` Thomas Gleixner
2016-01-15 21:11 ` Paul E. McKenney
2016-01-15 22:10 ` Paul E. McKenney
2016-01-15 23:14 ` Paul E. McKenney
2016-01-29 15:27 ` Peter Zijlstra
2016-01-31 0:28 ` Paul E. McKenney [this message]
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=20160131002825.GJ6719@linux.vnet.ibm.com \
--to=paulmck@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=sasha.levin@oracle.com \
--cc=tglx@linutronix.de \
/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.