Subject: arm64 function_graph tracer panic with CONFIG_DYNAMIC_FTRACE

From: [email-masked] (Lorenzo Pieralisi)
Date: Mon, 16 Nov 2015 15:48:22 +0000

On Mon, Nov 16, 2015 at 01:45:19PM +0000, Catalin Marinas wrote:

[...]

> > There are some other functions which are called by cpu_suspend(), e.g. psci_system_suspend().
> > Should we apply a similar fix to them?
> 
> I think we need to apply the fix to any function which does not return.
> In general, this should apply to all finishers passed to cpu_suspend()
> and the subsequent callees.

Yes, I prefer Steven's suggestion though it seems to me the issue
is only related to the graph tracer and by pausing/resuming tracing
across cpu_suspend() we would solve the problem without having to
patch the finishers (and we can still trace them with the function
tracer).

Takahiro, do you want me to send a patch or you update yours ?

> Do we need such annotation for cpu_die() as well? It probably doesn't
> matter as the CPU is coming back on a completely different path anyway.

I will test this too in the process.

Thanks for debugging this,
Lorenzo