From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Dave Hansen <dave@sr71.net>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
linux-next <linux-next@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Kristen Carlson Accardi <kristen@linux.intel.com>,
"H. Peter Anvin" <hpa@linux.intel.com>,
Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: linux-next: Tree for Feb 4
Date: Thu, 5 Feb 2015 08:58:20 -0800 [thread overview]
Message-ID: <20150205165819.GY5370@linux.vnet.ibm.com> (raw)
In-Reply-To: <CA+icZUX0iVY-Ng0xk6+4Du=2g5D1CudT54Y_ynmJkFA7dhWLHQ@mail.gmail.com>
On Thu, Feb 05, 2015 at 03:57:12PM +0100, Sedat Dilek wrote:
> On Thu, Feb 5, 2015 at 8:14 AM, Dave Hansen <dave@sr71.net> wrote:
> > On 02/04/2015 05:53 PM, Sedat Dilek wrote:
> >> The architecture-specific switch_mm() function can be called by offline
> >> CPUs, but includes event tracing, which cannot be legally carried out
> >> on offline CPUs. This results in a lockdep-RCU splat. This commit fixes
> >> this splat by omitting the tracing when the CPU is offline.
> > ...
> >>>> >> > load_cr3(next->pgd);
> >>>> >> > - trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
> >>>> >> > + if (cpu_online(smp_processor_id()))
> >>>> >> > + trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
> >
> > Is this, perhaps, something that we should be doing in the generic trace
> > code so that all of the trace users don't have to worry about it? Also,
> > this patch will add overhead to the code when tracing is off. It would
> > be best if we could manage to make the cpu_online() check only in the
> > cases where the tracepoint is on.
>
> Hi Dave,
>
> thanks for your feedback.
>
> I have just seen that I again see the call-trace.
When you get well, could you please send that call trace?
> Maybe you can discuss with Paul and others or offer a proposal patch.
The other possibility is to have a CONFIG_ARCH_DYING_IDLE or some such
that allows this particular flavor of x86 to invoke the CPU_DYING_IDLE
from after the call to switch_mm(). Dave, does that make sense?
My guess would be that there should be a cpu_dying_idle_generic() invoked
from cpu_idle_loop(), and a cpu_dying_idle_native() invoked at the end
of idle_task_exit(). Or can I get away with just moving the current
rcu_notify_cpu() call from cpu_idle_loop() to the end of idle_task_exit()?
A quick look at the calls to idle_task_exit() makes this look plausible.
There are a number of calls to printk() and to complete() that need help,
but that is a pre-existing issue in any case, as both these code paths
have RCU readers that are having no effect on offline CPUs.
Dave, thoughts?
> I should really do something for my recovery (influenza).
> Instead of laying lazy in my bed I thought to update my Linux kernels
> and graphics driver stack which made me happy.
Get well, being sick is bad for your health! ;-)
Thanx, Paul
> Regards,
> - Sedat -
>
next prev parent reply other threads:[~2015-02-05 16:58 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-04 8:35 linux-next: Tree for Feb 4 Stephen Rothwell
2015-02-04 12:26 ` Sedat Dilek
2015-02-04 15:16 ` Jens Axboe
2015-02-04 15:21 ` Sedat Dilek
2015-02-04 15:31 ` Jens Axboe
2015-02-04 15:36 ` Sedat Dilek
2015-02-04 15:58 ` Martin K. Petersen
2015-02-04 16:06 ` Sedat Dilek
2015-02-05 3:17 ` Martin K. Petersen
2015-02-05 3:41 ` Sedat Dilek
2015-02-05 19:46 ` Sedat Dilek
2015-02-06 15:24 ` Sedat Dilek
2015-02-04 20:18 ` Sedat Dilek
2015-02-04 21:54 ` Rafael J. Wysocki
2015-02-04 21:53 ` Paul E. McKenney
2015-02-04 22:59 ` Rafael J. Wysocki
2015-02-04 23:51 ` Paul E. McKenney
2015-02-04 23:58 ` Sedat Dilek
2015-02-05 0:10 ` Paul E. McKenney
2015-02-05 0:30 ` Sedat Dilek
2015-02-05 0:57 ` Paul E. McKenney
2015-02-05 1:18 ` Sedat Dilek
2015-02-05 1:51 ` Paul E. McKenney
2015-02-05 1:53 ` Sedat Dilek
2015-02-05 2:12 ` Sedat Dilek
2015-02-05 4:13 ` Paul E. McKenney
2015-02-05 7:14 ` Dave Hansen
2015-02-05 14:37 ` Paul E. McKenney
2015-02-05 14:57 ` Sedat Dilek
2015-02-05 16:58 ` Paul E. McKenney [this message]
2015-02-05 18:03 ` Steven Rostedt
2015-02-05 18:08 ` Steven Rostedt
2015-02-05 18:11 ` Dave Hansen
2015-02-05 18:34 ` Paul E. McKenney
2015-02-05 18:35 ` Dave Hansen
2015-02-05 18:45 ` Paul E. McKenney
2015-02-05 19:25 ` Sedat Dilek
2015-02-05 19:33 ` Paul E. McKenney
2015-02-05 19:42 ` Sedat Dilek
2015-02-05 19:58 ` Steven Rostedt
2015-02-05 20:07 ` Sedat Dilek
2015-02-05 20:22 ` Steven Rostedt
2015-02-05 20:50 ` Sedat Dilek
2015-02-05 21:45 ` Sedat Dilek
2015-02-05 22:09 ` Steven Rostedt
2015-02-05 22:16 ` Sedat Dilek
2015-02-05 23:11 ` Steven Rostedt
2015-02-05 23:53 ` Sedat Dilek
2015-02-06 0:03 ` Sedat Dilek
2015-02-06 0:12 ` Steven Rostedt
2015-02-06 0:14 ` Sedat Dilek
2015-02-04 22:38 ` Sedat Dilek
2015-02-04 23:25 ` Rafael J. Wysocki
2015-02-04 23:54 ` Sedat Dilek
2015-02-04 22:46 ` Sedat Dilek
2015-02-04 23:30 ` Rafael J. Wysocki
2015-02-04 23:48 ` Sedat Dilek
-- strict thread matches above, loose matches on Subject: below --
2022-02-04 4:14 Stephen Rothwell
2021-02-04 9:13 Stephen Rothwell
2020-02-04 4:19 Stephen Rothwell
2019-02-04 5:35 Stephen Rothwell
2016-02-04 3:48 Stephen Rothwell
2014-02-04 5:07 Stephen Rothwell
[not found] ` <CAP=VYLpgLC_4yuPtQH_yAd8S9cqQAVu2uB2=Wf3q_zgY4uzkLw@mail.gmail.com>
2014-02-04 22:23 ` Stephen Rothwell
2014-02-05 0:41 ` Stephen Rothwell
2013-02-04 7:39 Stephen Rothwell
2013-02-04 13:56 ` James Hogan
2013-02-04 20:33 ` Stephen Rothwell
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