sched/core: Check cpus_mask, not cpus_ptr in __set_cpus_allowed_ptr(), to fix mask...

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: Scott Wood <swood@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200617121742.cpxppyi7twxmpin7@linutronix.de

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8f360326861ec866d5ffb206f8a4c7bc47520350..9eeac94224db240a10fc92e4ddddbea493211406 100644 (file)
--- 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;
        }
 
                goto out;
        }
 

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

                goto out;
 
        /*
                goto out;
 
        /*