Re: rb tree hrtimer lockup bug (found by perf_fuzzer)
From: Thomas Gleixner
Date: Tue Mar 18 2014 - 16:53:02 EST
On Tue, 18 Mar 2014, Vince Weaver wrote:
> On Tue, 18 Mar 2014, Thomas Gleixner wrote:
> > On Tue, 18 Mar 2014, Vince Weaver wrote:
> > >
> > > The perf_fuzzer can quickly cause a machine to lockup with an hrtimer
> > > related rb tree related oops. I've had a hard time debugging this in any
> > > useful manner, but I can trigger it on both core2 and haswell test systems
> > > on 3.14-rc7.
> > >
> > > This involves making a large number of perf_event events of all types and
> > > then forking a lot.
> > Can you enable debugobjects please? The should give us an hint what
> > corrupts the rbtree.
> I enabled debugobjects and then said Y to most of the questions brought up
> by make oldconfig but now the system crashes at boot:
> [ 3.678040] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
> [ 3.686776] IP: [<ffffffff8106d7a8>] get_next_timer_interrupt+0x168/0x250
The back trace is not really helpful. Is there anything before that
BUG in dmesg?
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