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    SubjectRe: [V2 PATCH 0/6] x86, NMI: give NMI handler a face-lift
    On Fri, Nov 12, 2010 at 09:05:03AM -0600, Jason Wessel wrote:
    > On 11/12/2010 08:43 AM, Don Zickus wrote:
    > > Restructuring the nmi handler to be more readable and simpler.
    > >
    > > This is just laying the ground work for future improvements in this area.
    > >
    > > I also left out one of Huang's patch until we figure out how we are going
    > > to proceed with a new notifier.
    > >
    > > Tested 32-bit and 64-bit on AMD and Intel machines.
    > >
    > > V2: add a patch to kill DIE_NMI_IPI and add in priorities
    > >
    > >
    > Had you tested this code with kgdb boot tests at all?
    > There has been a regression in kgdb due to the use of perf/NMI in the
    > lockup detector ever since the new version has been introduced. The
    > perf callbacks in the lockup detector were consuming NMI events not
    > related to the call back and causing the kernel debugger not to work at
    > all on SMP systems configured with the lockup detector.

    Well 2.6.36 should have fixed that. Perf was blindly eating all NMI
    events if it had a user. With the new lockup detector, that created a
    'user' for perf and it happily ate everything. But we spent a lot of time
    trying to fix that for 2.6.36. If we missed something, we would like to

    To answer your question, I doubt this patch series will change that
    outcome if it is still broken.

    > I was curious to know if this patch series fixed the problem as well as
    > to know if you could run the regression test when you make changes
    > related to the lockup / NMI path as it affects the kernel debug API.

    Absolutely. I look forward to running tests with consumers of NMI other
    than perf. :-)

    Thanks for the tip.


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