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

From: Juri Lelli
Date: Thu May 14 2015 - 11:01:50 EST


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

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