On resume from suspend only CPU 0 comes back on-line [REGRESSION][BISECTED]

On resume from suspend only CPU 0 comes back on-line [REGRESSION][BISECTED]

[Doug Smythies]

As of, or about, Kernel 4.1RC1 on resume from suspend only CPU 0 comes back on-line.
The issue persists through Kernel 4.1RC3.
This is on my test computer with an i7-2600K.
I do not normally use suspend on this computer, but was doing so while working on a bug report.

The kernel was bisected, and this is the result:

3c18d447b3b36a8d3c90dc37dfbd363cdb685d0a is the first bad commit
commit 3c18d447b3b36a8d3c90dc37dfbd363cdb685d0a
Author: Juri Lelli <juri.lelli@arm.com>
Date:   Tue Mar 31 09:53:37 2015 +0100

    sched/core: Check for available DL bandwidth in cpuset_cpu_inactive()

    Hotplug operations are destructive w.r.t. cpusets. In case such an
    operation is performed on a CPU belonging to an exlusive cpuset, the
    DL bandwidth information associated with the corresponding root
    domain is gone even if the operation fails (in sched_cpu_inactive()).

    For this reason we need to move the check we currently have in
    sched_cpu_inactive() to cpuset_cpu_inactive() to prevent useless
    cpusets reconfiguration in the CPU_DOWN_FAILED path.

    Signed-off-by: Juri Lelli <juri.lelli@arm.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Cc: Juri Lelli <juri.lelli@gmail.com>
    Link: http://lkml.kernel.org/r/1427792017-7356-2-git-send-email-juri.lelli@arm.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>

:040000 040000 10f8d81afdc8e625f8e6720883d3eb42c28d452b c08264528890941bad35d5d4cc134c03f259c534 M      kernel

Since I sometimes mess up using git bisect, and end up at some random result,
the above was double checked manually:

3c18d447b3b36a8d3c90dc37dfbd363cdb685d0a has the issue.
4cd57f97135840f637431c92380c8da3edbe44ed (the previous commit) does not have the issue.

Re: On resume from suspend only CPU 0 comes back on-line [REGRESSION][BISECTED]

[Juri Lelli]

Hi Doug,

On 14/05/15 15:41, Doug Smythies wrote:
> As of, or about, Kernel 4.1RC1 on resume from suspend only CPU 0 comes back on-line.
> The issue persists through Kernel 4.1RC3.
> This is on my test computer with an i7-2600K.
> I do not normally use suspend on this computer, but was doing so while working on a bug report.
> 
> The kernel was bisected, and this is the result:
> 

Does commit 533445c6e533 "sched/core: Fix regression in
cpuset_cpu_inactive() for suspend" on tip/sched/core
fix the bug?

Thanks,

- Juri

> 3c18d447b3b36a8d3c90dc37dfbd363cdb685d0a is the first bad commit
> commit 3c18d447b3b36a8d3c90dc37dfbd363cdb685d0a
> Author: Juri Lelli <juri.lelli@arm.com>
> Date:   Tue Mar 31 09:53:37 2015 +0100
> 
>     sched/core: Check for available DL bandwidth in cpuset_cpu_inactive()
> 
>     Hotplug operations are destructive w.r.t. cpusets. In case such an
>     operation is performed on a CPU belonging to an exlusive cpuset, the
>     DL bandwidth information associated with the corresponding root
>     domain is gone even if the operation fails (in sched_cpu_inactive()).
> 
>     For this reason we need to move the check we currently have in
>     sched_cpu_inactive() to cpuset_cpu_inactive() to prevent useless
>     cpusets reconfiguration in the CPU_DOWN_FAILED path.
> 
>     Signed-off-by: Juri Lelli <juri.lelli@arm.com>
>     Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
>     Cc: Juri Lelli <juri.lelli@gmail.com>
>     Link: http://lkml.kernel.org/r/1427792017-7356-2-git-send-email-juri.lelli@arm.com
>     Signed-off-by: Ingo Molnar <mingo@kernel.org>
> 
> :040000 040000 10f8d81afdc8e625f8e6720883d3eb42c28d452b c08264528890941bad35d5d4cc134c03f259c534 M      kernel
> 
> Since I sometimes mess up using git bisect, and end up at some random result,
> the above was double checked manually:
> 
> 3c18d447b3b36a8d3c90dc37dfbd363cdb685d0a has the issue.
> 4cd57f97135840f637431c92380c8da3edbe44ed (the previous commit) does not have the issue.
> 
> 

Re: On resume from suspend only CPU 0 comes back on-line [REGRESSION][BISECTED]

[Ingo Molnar]

* Juri Lelli <juri.lelli@arm.com> wrote:

> Hi Doug,
> 
> On 14/05/15 15:41, Doug Smythies wrote:
> > As of, or about, Kernel 4.1RC1 on resume from suspend only CPU 0 comes back on-line.
> > The issue persists through Kernel 4.1RC3.
> > This is on my test computer with an i7-2600K.
> > I do not normally use suspend on this computer, but was doing so while working on a bug report.
> > 
> > The kernel was bisected, and this is the result:
> > 
> 
> Does commit 533445c6e533 "sched/core: Fix regression in
> cpuset_cpu_inactive() for suspend" on tip/sched/core
> fix the bug?

That would be sched/urgent primarily, not sched/core:

  git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/urgent

I'll get this fix to Linus ASAP.

Thanks,

	Ingo

RE: On resume from suspend only CPU 0 comes back on-line [REGRESSION][BISECTED]

[Doug Smythies]

On 2015.05.14 10:48 Ingo Molnar wrote:

> * Juri Lelli <juri.lelli@arm.com> wrote:
>>> On 14/05/15 15:41, Doug Smythies wrote:
>>> As of, or about, Kernel 4.1RC1 on resume from suspend only CPU 0 comes back on-line.
>>> The issue persists through Kernel 4.1RC3.
>>> This is on my test computer with an i7-2600K.
>>> I do not normally use suspend on this computer, but was doing so while working on a bug report.
>>> 
>>> The kernel was bisected, and this is the result:
>>> 
>> 
>> Does commit 533445c6e533 "sched/core: Fix regression in
>> cpuset_cpu_inactive() for suspend" on tip/sched/core
>> fix the bug?

> That would be sched/urgent primarily, not sched/core:
> git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/urgent
> I'll get this fix to Linus ASAP.

I could not seem to figure out how to get the patch from tip,
and any version I could find on internet would not apply properly.
 
Juri kindly sent me the patch.

With the patch applied to an otherwise unmodified Kernel 4.1RC3,
Resume from suspend is working fine again.

Thanks.

Re: On resume from suspend only CPU 0 comes back on-line [REGRESSION][BISECTED]

[Ingo Molnar]

* Doug Smythies <dsmythies@telus.net> wrote:

> On 2015.05.14 10:48 Ingo Molnar wrote:
> 
> > * Juri Lelli <juri.lelli@arm.com> wrote:
> >>> On 14/05/15 15:41, Doug Smythies wrote:
> >>> As of, or about, Kernel 4.1RC1 on resume from suspend only CPU 0 comes back on-line.
> >>> The issue persists through Kernel 4.1RC3.
> >>> This is on my test computer with an i7-2600K.
> >>> I do not normally use suspend on this computer, but was doing so while working on a bug report.
> >>> 
> >>> The kernel was bisected, and this is the result:
> >>> 
> >> 
> >> Does commit 533445c6e533 "sched/core: Fix regression in
> >> cpuset_cpu_inactive() for suspend" on tip/sched/core
> >> fix the bug?
> 
> > That would be sched/urgent primarily, not sched/core:
> > git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/urgent
> > I'll get this fix to Linus ASAP.
> 
> I could not seem to figure out how to get the patch from tip,
> and any version I could find on internet would not apply properly.

So the way you could have picked it up is something like:

  # pick up 533445c6e533
  git fetch git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/urgent
  git cherry-pick 533445c6e533

or pick up all pending scheduler fixes, amongst them 533445c6e533:

  git pull git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/urgent

Or to export just that single one as a patch:

  git fetch git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/urgent
  git log --pretty=email --stat -p -1 533445c6e533

> Juri kindly sent me the patch.
> 
> With the patch applied to an otherwise unmodified Kernel 4.1RC3, 
> Resume from suspend is working fine again.

Great, thanks for testing!

	Ingo

Re: On resume from suspend only CPU 0 comes back on-line [REGRESSION][BISECTED]

[Juri Lelli]

On 14/05/15 23:12, Doug Smythies wrote:
> On 2015.05.14 10:48 Ingo Molnar wrote:
> 
>> * Juri Lelli <juri.lelli@arm.com> wrote:
>>>> On 14/05/15 15:41, Doug Smythies wrote:
>>>> As of, or about, Kernel 4.1RC1 on resume from suspend only CPU 0 comes back on-line.
>>>> The issue persists through Kernel 4.1RC3.
>>>> This is on my test computer with an i7-2600K.
>>>> I do not normally use suspend on this computer, but was doing so while working on a bug report.
>>>>
>>>> The kernel was bisected, and this is the result:
>>>>
>>>
>>> Does commit 533445c6e533 "sched/core: Fix regression in
>>> cpuset_cpu_inactive() for suspend" on tip/sched/core
>>> fix the bug?
> 
>> That would be sched/urgent primarily, not sched/core:
>> git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/urgent
>> I'll get this fix to Linus ASAP.
> 
> I could not seem to figure out how to get the patch from tip,
> and any version I could find on internet would not apply properly.
>  
> Juri kindly sent me the patch.
> 
> With the patch applied to an otherwise unmodified Kernel 4.1RC3,
> Resume from suspend is working fine again.
>

Great! Thanks for testing :).

Best,

- Juri