On Thu, Sep 20, 2012 at 11:07:37AM +0200, Linus Walleij wrote:
> On Thu, Sep 20, 2012 at 2:03 AM, Paul E. McKenney
> <paul...@linux.vnet.ibm.com> wrote:
>
> > In the meantime, a crude fallback is for the CPU that detected the stall
> > to trace the stack of the task running on the other CPU. See below for
> > a crude (and untested) patch.
>
> OK now I get this:
>
> INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1,
> t=29508 jiffies)
> Task dump for CPU 0:
> swapper/0 R running 0 0 0 0x00000000
> [<c02da614>] (__schedule+0x238/0x52c) from [<c000f238>]
> (default_idle+0x28/0x30)
> [<c000f238>] (default_idle+0x28/0x30) from [<ffffffff>] (0xffffffff)
> INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1,
> t=29851 jiffies)
> Task dump for CPU 0:
> swapper/0 R running 0 0 0 0x00000000
> [<c02da614>] (__schedule+0x238/0x52c) from [<c000f238>]
> (default_idle+0x28/0x30)
> [<c000f238>] (default_idle+0x28/0x30) from [<ffffffff>] (0xffffffff)
>
> So the swapper thread is the culprit?
> Hm, I'm not very smart with this no...
Can we convince ARM to dump the stack of the swapper thread in this case?
That would get us valuable information.
Thanx, Paul
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