[release-0.7] Fix panic when not enough quota on FairSharing enabled.

pkg/scheduler/scheduler.go

@@ -361,7 +361,7 @@ func (s *Scheduler) nominate(ctx context.Context, workloads []workload.Info, sna
 			e.assignment, e.preemptionTargets = s.getAssignments(log, &e.Info, &snap)
 			e.inadmissibleMsg = e.assignment.Message()
 			e.Info.LastAssignment = &e.assignment.LastState
-			if s.fairSharing.Enable {
+			if s.fairSharing.Enable && e.assignment.RepresentativeMode() != flavorassigner.NoFit {
 				e.dominantResourceShare, e.dominantResourceName = cq.DominantResourceShareWith(e.assignment.TotalRequestsFor(&w))
 			}
 		}

pkg/scheduler/scheduler_test.go

@@ -1649,6 +1649,33 @@ func TestSchedule(t *testing.T) {
 				"eng-gamma/gamma4":   *utiltesting.MakeAdmission("eng-gamma").Assignment(corev1.ResourceCPU, "on-demand", "20").Obj(),
 			},
 		},
+		"not enough resources": {
+			workloads: []kueue.Workload{
+				*utiltesting.MakeWorkload("new", "sales").
+					Queue("main").
+					PodSets(*utiltesting.MakePodSet("one", 1).
+						Request(corev1.ResourceCPU, "100").
+						Obj()).
+					Obj(),
+			},
+			wantLeft: map[string][]string{
+				"sales": {"sales/new"},
+			},
+		},
+		"not enough resources with fair sharing enabled": {
+			enableFairSharing: true,
+			workloads: []kueue.Workload{
+				*utiltesting.MakeWorkload("new", "sales").
+					Queue("main").
+					PodSets(*utiltesting.MakePodSet("one", 1).
+						Request(corev1.ResourceCPU, "100").
+						Obj()).
+					Obj(),
+			},
+			wantLeft: map[string][]string{
+				"sales": {"sales/new"},
+			},
+		},
 	}
 
 	for name, tc := range cases {

test/integration/scheduler/fairsharing/fair_sharing_test.go

@@ -161,6 +161,26 @@ var _ = ginkgo.Describe("Scheduler", func() {
 				g.Expect(createdCqA.Status.FairSharing).Should(gomega.BeComparableTo(&kueue.FairSharingStatus{WeightedShare: 125}))
 			}, util.Timeout, util.Interval).Should(gomega.Succeed())
 		})
+
+		ginkgo.It("Shouldn't reserve quota because not enough resources", func() {
+			wl := testing.MakeWorkload("wl", ns.Name).
+				Queue(lqA.Name).
+				Request("cpu", "10").
+				Obj()
+			gomega.Expect(k8sClient.Create(ctx, wl)).Should(gomega.Succeed())
+
+			gomega.Eventually(func(g gomega.Gomega) {
+				g.Expect(k8sClient.Get(ctx, client.ObjectKeyFromObject(wl), wl)).Should(gomega.Succeed())
+				g.Expect(wl.Status.Conditions).To(gomega.ContainElements(
+					gomega.BeComparableTo(metav1.Condition{
+						Type:    kueue.WorkloadQuotaReserved,
+						Status:  metav1.ConditionFalse,
+						Reason:  "Pending",
+						Message: "couldn't assign flavors to pod set main: insufficient unused quota in cohort for cpu in flavor default, 2 more needed",
+					}, util.IgnoreConditionTimestampsAndObservedGeneration),
+				))
+			}, util.Timeout, util.Interval).Should(gomega.Succeed())
+		})
 	})
 
 	ginkgo.When("Preemption is enabled", func() {