diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 7d800b306056..af2cbab14497 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -2516,10 +2516,13 @@ static void mba_sc_domain_destroy(struct rdt_resource *r,
 }
 
 /*
- * MBA software controller is supported only if
- * MBM is supported and MBA is in linear scale,
- * and the MBM monitor scope is the same as MBA
- * control scope.
+ * The MBA software controller is supported only if MBM is supported and MBA is
+ * in linear scale, and the MBM monitor scope is the same as MBA control scope.
+ *
+ * The software controller cannot be supported when the MBM counters are
+ * assignable.  There is no guarantee that MBM counters are assigned to the
+ * event backing the software controller in all monitoring domains of all
+ * monitoring groups.
  */
 static bool supports_mba_mbps(void)
 {
@@ -2528,7 +2531,8 @@ static bool supports_mba_mbps(void)
 
 	return (resctrl_is_mbm_enabled() &&
 		r->alloc_capable && is_mba_linear() &&
-		r->ctrl_scope == rmbm->mon_scope);
+		r->ctrl_scope == rmbm->mon_scope &&
+		!rmbm->mon.mbm_cntr_assignable);
 }
 
 /*
@@ -2943,7 +2947,7 @@ static int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		ctx->enable_cdpl2 = true;
 		return 0;
 	case Opt_mba_mbps:
-		msg = "mba_MBps requires MBM and linear scale MBA at L3 scope";
+		msg = "mba_MBps requires MBM (mbm_event mode not supported) and linear scale MBA at L3 scope";
 		if (!supports_mba_mbps())
 			return invalfc(fc, msg);
 		ctx->enable_mba_mbps = true;