Messages in this thread | | | Date | Mon, 13 May 2013 08:59:48 -0500 | From | Robin Holt <> | Subject | Re: Full dynticks needs evtdesc set before marking cpu online. |
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On Mon, May 13, 2013 at 03:03:55PM +0200, Thomas Gleixner wrote: > On Mon, 13 May 2013, Robin Holt wrote: > > > On Mon, May 13, 2013 at 11:21:00AM +0200, Thomas Gleixner wrote: > > > On Wed, 8 May 2013, Robin Holt wrote: > > > > > > > Thomas, > > > > > > > > We are seeing failures booting medium sized machines which I think is > > > > a change in expectations that dyntick put on x86's start_secondary. > > > > > > > > During boot of cpus, we see an occassional panic in tick_do_broadcast at > > > > > > http://lkml.indiana.edu/hypermail/linux/kernel/1305.0/01818.html > > > > > > Will hit Linus tree soon. > > > > I think this is really due to a sequence in start_secondary. The cpu > > has been marked as online, but its evtdesc has not been initialized. > > I sent a followup to this with a hack/patch. > > No, the real issue is that I messed up the cpumask conversion in the > broadcast code, i.e. using alloc instead of zalloc, which allocated > nonzeroed memory for the cpumasks, so any random bit set will crash > the machine. Your patch is just papering over the issue.
I believe I understand now. What would be the downside of moving the initialization to before marking the cpu online? It seems like a reasonable this to expect as well in spite of it not being the right fix to the other bug.
Thanks, Robin
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