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From: Ingo Molnar on 17 Mar 2010 15:40

* Paul E. McKenney <paulmck(a)linux.vnet.ibm.com> wrote:

> On Wed, Mar 17, 2010 at 06:53:11PM +0100, Ingo Molnar wrote:
> >
> > * Ingo Molnar <mingo(a)elte.hu> wrote:
> >
> > > incidentally i have a RCU badness crash log from another box:
> > >
> > > [ 4.573332] initcall ipmi_init_msghandler_mod+0x0/0xd returned 0 after 0 usecs
> > > [ 4.573332] calling init_ipmi_si+0x0/0x435 @ 1
> > > [ 4.573332] IPMI System Interface driver.
> > > [ 4.573340] [<ffffffff81022cdc>] no_context+0x1fc/0x20b
> > > [ 4.576672] [<ffffffff81002a16>] ? ftrace_call+0x5/0x2b
> > > [ 4.580021] [<ffffffff81022e77>] __bad_area_nosemaphore+0x18c/0x1af
> > > [ 4.583338] [<ffffffff81002a16>] ? ftrace_call+0x5/0x2b
> > > [ 4.586672] [<ffffffff81022ead>] bad_area_nosemaphore+0x13/0x15
> > > [ 4.590005] [<ffffffff81023159>] do_page_fault+0x138/0x284
> > > [ 4.593354] [<ffffffff81a632bf>] page_fault+0x1f/0x30
> >
> > I spent a few hours yesterday and today trying to track this down, but failed
> > to bisect it. The crash is sporadic on many configs - which confused my
> > bisection attempts. Sometimes it crashes only after 10 reboots. Was able to
> > crash v2.6.30 as well, so it's an older bug. v2.6.29 was not testable on that
> > box due to network driver problems so i stopped there.
>
> OK, I give up...
>
> What did you change about your testing? ;-)

Nothing really - and it has not reoccured on that box since i let it move on
to another random config. This might be a 1:100000 kind of blue moon bug.
(literally)

My suspicion is that it's an ftrace bug, all the crashes happened during
function-tracer self-tests.

Ingo
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