From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
commit 386ef214c3c6ab111d05e1790e79475363abaa05 upstream.
try_steal_cookie() looks at task_struct::cpus_mask to decide if the
task could be moved to `this' CPU. It ignores that the task might be in
a migration disabled section while not on the CPU. In this case the task
must not be moved otherwise per-CPU assumption are broken.
Use is_cpu_allowed(), as suggested by Peter Zijlstra, to decide if the a
task can be moved.
Fixes: d2dfa17bc7de6 ("sched: Trivial forced-newidle balancer")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/YjNK9El+3fzGmswf@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5929,7 +5929,7 @@ static bool try_steal_cookie(int this, i
if (p == src->core_pick || p == src->curr)
goto next;
- if (!cpumask_test_cpu(this, &p->cpus_mask))
+ if (!is_cpu_allowed(p, this))
goto next;
if (p->core_occupation > dst->idle->core_occupation)
