On Thu 2018-01-25 10:04:44, Peter Zijlstra wrote: > On Mon, Feb 13, 2017 at 07:42:40PM -0600, Josh Poimboeuf wrote: > > diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c > > index 6a4bae0..a8b3f1a 100644 > > --- a/kernel/sched/idle.c > > +++ b/kernel/sched/idle.c > > @@ -9,6 +9,7 @@ > > #include <linux/mm.h> > > #include <linux/stackprotector.h> > > #include <linux/suspend.h> > > +#include <linux/livepatch.h> > > > > #include <asm/tlb.h> > > > > @@ -264,6 +265,9 @@ static void do_idle(void) > > > > sched_ttwu_pending(); > > schedule_preempt_disabled(); > > + > > + if (unlikely(klp_patch_pending(current))) > > + klp_update_patch_state(current); > > } > > Can someone explain this one? This is a very weird place to add things. > What was the expectation? AFAIK, it was the least ugly and minimalist solution that we came with. The tasks are migrated to the new patch when neither of the patched functions is on the stack. The stack can be checked safely only when the task is not running. It might be very hard to catch the idle task on a such a place if we patch something that is used there. If the idle task is scheduled, you would need to create some fake load on the system, try to migrate the idle task, stop the fake load on the CPU. The above code makes the idle task to migrate itself on a sane place. You just need to schedule some minimalist job on the CPU. The idle task will do one loop, gets migrated, and might be scheduled again immediately. Best Regards, Petr -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
