bugfix(scheduler): preemption picks wrong victim node with higher priority pod on it.

Introducing pdb to preemption had disrupted the orderliness of pods in the victims,
which would leads picking wrong victim node with higher priority pod on it.

pkg/scheduler/framework/plugins/defaultpreemption/default_preemption.go

@@ -191,6 +191,8 @@ func (pl *DefaultPreemption) SelectVictimsOnNode(
 	}
 	var victims []*v1.Pod
 	numViolatingVictim := 0
+	// Sort potentialVictims by pod priority from high to low, which ensures to
+	// reprieve higher priority pods first.
 	sort.Slice(potentialVictims, func(i, j int) bool { return util.MoreImportantPod(potentialVictims[i].Pod, potentialVictims[j].Pod) })
 	// Try to reprieve as many pods as possible. We first try to reprieve the PDB
 	// violating victims and then other non-violating ones. In both cases, we start
@@ -225,6 +227,11 @@ func (pl *DefaultPreemption) SelectVictimsOnNode(
 			return nil, 0, framework.AsStatus(err)
 		}
 	}
+
+	// Sort victims after reprieving pods to keep the pods in the victims sorted in order of priority from high to low.
+	if len(violatingVictims) != 0 && len(nonViolatingVictims) != 0 {
+		sort.Slice(victims, func(i, j int) bool { return util.MoreImportantPod(victims[i], victims[j]) })
+	}
 	return victims, numViolatingVictim, framework.NewStatus(framework.Success)
 }