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

[tip-bot2 for Scott Wood]

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@xxxxxxxxxx>
AuthorDate:    Wed, 17 Jun 2020 14:17:42 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Signed-off-by: Scott Wood <swood@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200617121742.cpxppyi7twxmpin7@xxxxxxxxxxxxx
---
 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;
 
 	/*