AutoDetect=nvml: Fatal if no devices found in MIG mode

Bug 12174

NEWS

@@ -6,6 +6,7 @@ documents those changes that are of interest to users and administrators.
  -- Fix potential memory leak if a problem happens while allocating GRES for
     a job.
  -- If an overallocation of GRES happens terminate the creation of a job.
+ -- AutoDetect=nvml: Fatal if no devices found in MIG mode.
 * Changes in Slurm 21.08.0
 ==========================

src/plugins/gpu/nvml/gpu_nvml.c

@@ -1674,6 +1674,8 @@ static List _get_system_gpu_list_nvml(node_config_load_t *node_config)
 					break;
 			}
 			debug2("    MIG count: %u", mig_count);
+			if (mig_count == 0)
+				fatal("MIG mode is enabled, but no MIG devices were found. Please either create MIG instances, disable MIG mode, remove AutoDetect=nvml, or remove GPUs from the configuration completely.");
 
 			for (unsigned int j = 0; j < mig_count; j++) {
 				nvml_mig_t nvml_mig = { 0 };