mm/sharepool: Fix a double free problem caused by init_local_group

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I64Y5Y
CVE: NA

-------------------------------

If local_group_add_task fails in init_local_group. ida free the
same id twice.

init_local_group
  local_group_add_task    // failed
  goto free_spg

free_spg:
  free_sp_group_locked
    free_sp_group_id      // free spg->id
free_spg_id:
  free_new_spg_id         // double free spg->id

To fix it, return before calling free_new_spg_id.
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NGuo Mengqi <guomengqi3@huawei.com>
Reviewed-by: Nchenweilong <chenweilong@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

mm/share_pool.c

@@ -301,8 +301,8 @@ static int init_local_group(struct mm_struct *mm)
 
 	spg = create_spg(spg_id, 0);
 	if (IS_ERR(spg)) {
-		ret = PTR_ERR(spg);
-		goto free_spg_id;
+		free_new_spg_id(true, spg_id);
+		return PTR_ERR(spg);
 	}
 
 	master->local = spg;
@@ -322,11 +322,9 @@ static int init_local_group(struct mm_struct *mm)
 	return 0;
 
 free_spg:
+	/* spg_id is freed in free_sp_group_locked */
 	free_sp_group_locked(spg);
 	master->local = NULL;
-free_spg_id:
-	free_new_spg_id(true, spg_id);
-
 	return ret;
 }