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    SubjectRe: [PATCH bisected regression] sched: rebuild sched domains at suspend/resume

    * Srivatsa S. Bhat <> wrote:

    > On 03/07/2012 02:15 AM, Konstantin Khlebnikov wrote:
    > > This is fix for suspend/resume regression introduced in
    > > commit 8f2f748b0656 ("CPU hotplug, cpusets, suspend: Don't
    > > touch cpusets during suspend/resume") Without this patch
    > > suspend always hangs on my thinkpad x220 (2 x CPU * HT).
    > Hey, with commit 8f2f748b0656, suspend/resume works perfectly
    > for me! I ran it multiple times just to make sure, and
    > everything worked just great.
    > Apart from that, I even tried suspend/resume after building
    > the kernel with and without CONFIG_CPUSETS. Both cases worked
    > perfectly.
    > So, I am really surprised at what you stated above. Are you
    > *really* sure you are facing suspend hangs *because* of the
    > above commit?

    That's not the only information Konstantin gave: he also
    provided a patch, which activates a side-effect that got removed
    by your patch - and voila, s2ram was working for him again.

    At this point I don't think we should doubt the messenger, we
    should doubt our assumptions and we should go for a clean revert

    I don't see the underlying bug straight away, but clearly my
    assumptions of this patch not causing problems, when I applied
    the patch, are not valid anymore.

    So if Linus wants to revert the commit straight away:

    Acked-by: Ingo Molnar <>

    > And AFAICS hardware doesn't matter for the code in question, but in any case,
    > the laptop on which I tested it is:
    > Thinkpad T420 (Intel core i5-2540M), 2 cores * HT (total 4 logical cpus).

    Well, any environmental detail might matter as long as we don't
    understand the bug.

    > Also, the patch you posted here doesn't make much sense.. nor
    > does it give a clue as to what might be wrong at your end (if
    > anything is really wrong, that is). Do you have CONFIG_CPUSETS
    > set or unset? Could you share your .config?

    His patch is simply the re-creation of a side-effect that the
    kernel had before - and it made suspend work for him. While it
    is not a patch we want to apply, it sure was a valid and
    valuable experiment to perform.



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