Messages in this thread | | | Date | Wed, 7 Mar 2012 15:02:46 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH bisected regression] sched: rebuild sched domains at suspend/resume |
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* Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> 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 ASAP.
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 <mingo@elte.hu>
> 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.
Thanks,
Ingo
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