On Fri, Dec 04, 2020 at 12:54:29AM +0000, Alex Belits wrote: > > On Wed, 2020-12-02 at 14:20 +0000, Mark Rutland wrote: > > External Email > > > > ------------------------------------------------------------------- > > --- > > On Mon, Nov 23, 2020 at 05:58:22PM +0000, Alex Belits wrote: > > > From: Yuri Norov <ynorov@xxxxxxxxxxx> > > > > > > For nohz_full CPUs the desirable behavior is to receive interrupts > > > generated by tick_nohz_full_kick_cpu(). But for hard isolation it's > > > obviously not desirable because it breaks isolation. > > > > > > This patch adds check for it. > > > > > > Signed-off-by: Yuri Norov <ynorov@xxxxxxxxxxx> > > > [abelits@xxxxxxxxxxx: updated, only exclude CPUs running isolated > > > tasks] > > > Signed-off-by: Alex Belits <abelits@xxxxxxxxxxx> > > > --- > > > kernel/time/tick-sched.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > > > index a213952541db..6c8679e200f0 100644 > > > --- a/kernel/time/tick-sched.c > > > +++ b/kernel/time/tick-sched.c > > > @@ -20,6 +20,7 @@ > > > #include <linux/sched/clock.h> > > > #include <linux/sched/stat.h> > > > #include <linux/sched/nohz.h> > > > +#include <linux/isolation.h> > > > #include <linux/module.h> > > > #include <linux/irq_work.h> > > > #include <linux/posix-timers.h> > > > @@ -268,7 +269,8 @@ static void tick_nohz_full_kick(void) > > > */ > > > void tick_nohz_full_kick_cpu(int cpu) > > > { > > > - if (!tick_nohz_full_cpu(cpu)) > > > + smp_rmb(); > > > > What does this barrier pair with? The commit message doesn't mention > > it, > > and it's not clear in-context. > > With barriers in task_isolation_kernel_enter() > and task_isolation_exit_to_user_mode(). Please add a comment in the code as to what it pairs with. Thanks, Mark.