On 01/22/2015 10:59 AM, Michael Ellerman wrote: > On Fri, 2015-01-16 at 14:40 +0530, Preeti U Murthy wrote: >> On 01/16/2015 02:26 PM, Preeti U Murthy wrote: >>> On 01/16/2015 08:34 AM, Michael Ellerman wrote: >>>> On Fri, 2015-01-16 at 13:28 +1300, Alexey Kardashevskiy wrote: >>>>> On 01/16/2015 02:22 AM, Preeti U Murthy wrote: >>>>>> Hi Alexey, >>>>>> >>>>>> Can you let me know if the following patch fixes the issue for you ? >>>>>> It did for us on one of our machines that we were investigating on. >>>>> >>>>> This fixes the issue for me as well, thanks! >>>>> >>>>> Tested-by: Alexey Kardashevskiy <a...@ozlabs.ru> >>>> >>>> OK, that's great. >>>> >>>> But, I really don't think we can ask upstream to merge this patch to >>>> generic >>>> code when we don't have a good explanation for why it's necessary. At >>>> least I'm >>>> not going to ask anyone to do that :) >>>> >>>> So Pretti can you either write a 100% convincing explanation of why this >>>> patch >>>> is correct in the general case, or (preferably) do some more investigating >>>> to >>>> work out what Alexey's bug actually is. >>> >>> Yes will do so. Its better to investigate where precisely is the bug. >>> This patch helped me narrow down on the buggy scenario. >> >> On a side note, while I was tracking the race condition, I noticed that >> in the final stage of the cpu offline path, after the state of the >> hotplugged cpu is set to CPU_DEAD, we check if there were interrupts >> delivered during the soft disabled state and service them if there were. >> It makes sense to check for pending interrupts in the idle path. In the >> offline path however, this did not look right to me at first glance. Am >> I missing something ? > > That does sound a bit fishy. > > I guess we're just assuming that all interrupts have been migrated away prior > to the offline?
Yes they have. Interrupts to start a guest will also not get delivered because the hwthread_state is not set to nap yet at that point. Regards Preeti U Murthy > > cheers > > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev