[tip: sched/urgent] sched: __set_cpus_allowed_ptr(): Check cpus_mask, not cpus_ptr

tip-bot2 for Scott Wood
2020-06-23T07:20:06Z

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID: a51dde512a93959d1df3a915fa3e3df68b1fc94d
Gitweb: https://git.kernel.org/tip/a51dde512a93959d1df3a915fa3e3df68b1fc94d
Author: Scott Wood <swood@redhat.com>
AuthorDate: Wed, 17 Jun 2020 14:17:42 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 22 Jun 2020 20:51:05 +02:00

sched: __set_cpus_allowed_ptr(): Check cpus_mask, not cpus_ptr

This function is concerned with the long-term cpu mask, not the
transitory mask the task might have while migrate disabled. Before
this patch, if a task was migrate disabled at the time
__set_cpus_allowed_ptr() was called, and the new mask happened to be
equal to the cpu that the task was running on, then the mask update
would be lost.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Scott Wood <swood@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200617121742.cpxppyi7twxmpin7@linutronix.de
---
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8298b2c..9f8aa34 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1637,7 +1637,7 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
goto out;
}

- if (cpumask_equal(p->cpus_ptr, new_mask))
+ if (cpumask_equal(&p->cpus_mask, new_mask))
goto out;

/*