Re: [percpu] BUG: unable to handle kernel NULL pointer dereference at (null)

From: Fengguang Wu
Date: Thu Sep 04 2014 - 08:44:23 EST


On Tue, Sep 02, 2014 at 10:16:57AM -0700, Paul E. McKenney wrote:
> On Tue, Sep 02, 2014 at 11:55:58AM -0500, Christoph Lameter wrote:
> > On Tue, 2 Sep 2014, Paul E. McKenney wrote:
> >
> > > Added by ac1bea85781e (sched,rcu: Make cond_resched() report RCU quiescent
> > > states), removed by 4a81e8328d379 (rcu: Reduce overhead of cond_resched()
> > > checks for RCU). So, as you say, no effect on contemporary kernels.
> >
> > Well not sure what to make out of all of this....
>
> Yep, still confused as to how the patch adding the definition could have
> caused a failure. Fengguang, any thoughts?

Yeah this is confusing.. I checked carefully and find that commit
0e98023 and afea227 are built on 2 quite different servers -- which
might generate slightly different code. I'll fix this issue and make
the build server selection more consistent.

Thanks,
Fengguang
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