On Wed, Jul 08, 2026 at 11:11:47AM +0200, Sebastian Andrzej Siewior wrote:
> On 2026-07-07 09:39:01 [-0700], Paul E. McKenney wrote:
> > Alternatives include:
> >
> > o Provide a patch like that above, but only execute the
> > rcu_barrier() in some debug mode. If your code works when
> > that debug is enabled but does not otherwise, you add the
> > rcu_barrier().
> >
> > o If debug is enabled, make rcu_do_batch() check the function
> > before invoking it. If the function is not mapped, issue a
> > diagnostic, and don't try to invoke the function. (But is
> > there a sufficiently cheap way to check for the function not
> > being mapped?)
>
> In both cases you would see a backtrace and the name of the last
> unloaded module. And since we don't see a lot of these reports, people
> either don't run into this because it does not exist or RCU is quick
> enough.
Good point, the splat from calling the no-longer-mapped function should
call out the offending module. So maybe our debug code is good enough
already.
Thanx, Paul
