Re: CONFIG_NO_HZ + CONFIG_CPU_IDLE freeze the system (Was Re: [PATCH] acpi : remove power from acpi_processor_cx structure)

Rafael J. Wysocki
Thu, 06 Sep 2012 21:18:42 -0000

On Thursday, September 06, 2012, Daniel Lezcano wrote:
> On 09/06/2012 10:04 PM, Rafael J. Wysocki wrote:
> > On Thursday, September 06, 2012, Daniel Lezcano wrote:
> >> On 09/06/2012 09:54 AM, Daniel Lezcano wrote:
> >>> On 09/05/2012 03:41 PM, Rafael J. Wysocki wrote:
> >>>> On Saturday, September 01, 2012, Rafael J. Wysocki wrote:
> >>>>> On Friday, August 31, 2012, Daniel Lezcano wrote:
> >>>>>> On 07/24/2012 11:06 PM, Konrad Rzeszutek Wilk
wrote:
> >>>>>>> On Tue, Jul 24, 2012 at 11:12:29PM +0200,
Daniel Lezcano wrote:
> >>>>>>>> Remove the power field as it is not used.
> >>>>>>>>
> >>>>>>>> Signed-off-by: Daniel Lezcano
<daniel.lezcano@linaro.org>
> >>>>>>>> Cc: Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com>
> >>>>>>> Acked.
> >>>>>> Hi Rafael,
> >>>>>>
> >>>>>> I did not see this patch going in. Is it possible
to merge it ?
> >>>>> I think so.  I''ll take care of it when I get
back from LinuxCon/Plumbers Conf.
> >>>>> (early next week).
> >>>> Applied to the linux-next branch of the linux-pm.git tree
as v3.7 material.
> >>> Thanks Rafael.
> >>>
> >>>> Are there any other patches you want me to consider for
v3.7?
> >>> Yes please, I have the per cpu latencies ready to be submitted
but I
> >>> want to do extra testing before. Unfortunately, the
linux-pm-next hangs
> >>> at boot time on my intel dual core (not related to the
patchset).
> >>>
> >>> I am git bisecting right now.
> >>
> >> I found the culprit. This is not related to the linux-pm tree but
with
> >> net-next.
> >> The following patch introduced the issue.
> >>
> >> commit 6bdb7fe31046ac50b47e83c35cd6c6b6160a475d
> >> Author: Amerigo Wang <amwang@redhat.com>
> >> Date:   Fri Aug 10 01:24:50 2012 +0000
> >>
> >>     netpoll: re-enable irq in poll_napi()
> >>
> >>     napi->poll() needs IRQ enabled, so we have to re-enable IRQ
before
> >>     calling it.
> >>
> >>     Cc: David Miller <davem@davemloft.net>
> >>     Signed-off-by: Cong Wang <amwang@redhat.com>
> >>     Signed-off-by: David S. Miller <davem@davemloft.net>
> >>
> >> AFAICS, it has been fixed by commit
> >> 072a9c48600409d72aeb0d5b29fbb75861a06631 which is not yet in
linux-pm-next.
> >
> > If it is present in the current Linus'' tree, you can just
pull this one
> > and merge linux-pm-next into it.  It should merge without conflicts.
>
> Ok, thanks.
>
> >> I fall into this issue because NETCONSOLE is set, disabling it
allowed
> >> me to go further.
> >>
> >> Unfortunately I am facing to some random freeze on the system
which
> >> seems to be related to CONFIG_NO_HZ=y and CONFIG_CPU_IDLE=y.
> >>
> >> Disabling one of them, make the freezes to disappear.
> >>
> >> Is it a known issue ?
> >
> > Well, there are systems having problems with this configuration, but
they
> > should be exceptional.  What system is that?
>
> It is a laptop T61p with a Core 2 Duo T9500. Nothing exceptional I
> believe. Maybe someone got the same issue ?

Is it a regression for you?