sched_ext: Add migration-disabled counter to error state dump

Include the task's migration-disabled counter when dumping task state
during an error exit.

This can help diagnose cases where tasks can get stuck, because they're
unable to migrate elsewhere.

tj: s/nomig/no_mig/ for readability and consistency with other keys.

Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

kernel/sched/ext.c

@@ -4167,7 +4167,8 @@ static void scx_dump_task(struct seq_buf *s, struct scx_dump_ctx *dctx,
 		  p->scx.sticky_cpu, p->scx.holding_cpu, dsq_id_buf);
 	dump_line(s, "      dsq_vtime=%llu slice=%llu weight=%u",
 		  p->scx.dsq_vtime, p->scx.slice, p->scx.weight);
-	dump_line(s, "      cpus=%*pb", cpumask_pr_args(p->cpus_ptr));
+	dump_line(s, "      cpus=%*pb no_mig=%u", cpumask_pr_args(p->cpus_ptr),
+		  p->migration_disabled);
 
 	if (SCX_HAS_OP(sch, dump_task)) {
 		ops_dump_init(s, "    ");