On 13/10/20 15:15, Sebastian Andrzej Siewior wrote: > On 2020-10-13 15:01:15 [+0100], Valentin Schneider wrote: >> migrate_disable(); >> set_cpus_allowed_ptr(current, {something excluding task_cpu(current)}); >> affine_move_task(); <-- never returns >> >> Signed-off-by: Valentin Schneider <valentin.schnei...@arm.com> >> --- >> kernel/sched/core.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index 4ccd1099adaa..7f4e38819de1 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -2189,6 +2189,11 @@ static int __set_cpus_allowed_ptr(struct task_struct >> *p, >> if (!(flags & SCA_MIGRATE_ENABLE) && cpumask_equal(&p->cpus_mask, >> new_mask)) >> goto out; >> >> + if (p == current && >> + is_migration_disabled(p) && >> + !cpumask_test_cpu(task_cpu(p), new_mask)) >> + ret = -EBUSY; >> + > > This shouldn't happen, right? The function may sleep so it shouldn't be > entered with disabled migration. A WARN_ON might spot the bad caller. >
Yeah, this is one of those paranoia-driven checks. > Sebastian