sched/core: Fix a missed update of user_cpus_ptr

Since commit 8f9ea86fdf99 ("sched: Always preserve the user requested
cpumask"), a successful call to sched_setaffinity() should always save
the user requested cpu affinity mask in a task's user_cpus_ptr. However,
when the given cpu mask is the same as the current one, user_cpus_ptr
is not updated. Fix this by saving the user mask in this case too.

Fixes: 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230203181849.221943-1-longman@redhat.com

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e838feb6adc504605c85ff4f252d50a7198826c0..2a4918a1faa9ef0fef92720a72c1aed5bab75da3 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2951,8 +2951,11 @@ static int __set_cpus_allowed_ptr_locked(struct task_struct *p,
        }
 
        if (!(ctx->flags & SCA_MIGRATE_ENABLE)) {
-               if (cpumask_equal(&p->cpus_mask, ctx->new_mask))
+               if (cpumask_equal(&p->cpus_mask, ctx->new_mask)) {
+                       if (ctx->flags & SCA_USER)
+                               swap(p->user_cpus_ptr, ctx->user_mask);
                        goto out;
+               }
 
                if (WARN_ON_ONCE(p == current &&
                                 is_migration_disabled(p) &&