fs/resctrl: Free mon_data structures on rdt_get_tree() failure

If mkdir_mondata_all() or a subsequent call in rdt_get_tree() fails, the
mon_data structures allocated by mon_get_kn_priv() are leaked.

Add mon_put_kn_priv() to the out_mongrp error path to free the mon_data
structures.

Fixes: 2a65660 ("x86/resctrl: Expand the width of domid by replacing mon_data_bits")
Closes: https://lore.kernel.org/lkml/5d38c1fb-8f91-472b-8897-24b2f50c772b@intel.com/
Reported-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/433623b7e3316ffd52323255d1aa4f156ad97cb1.1783377598.git.reinette.chatre@intel.com

Author: aegl

fs/resctrl/rdtgroup.c

@@ -74,6 +74,8 @@ static int rdtgroup_setup_root(struct rdt_fs_context *ctx);
 
 static void rdtgroup_destroy_root(void);
 
+static void mon_put_kn_priv(void);
+
 struct dentry *debugfs_resctrl;
 
 /*
@@ -2893,6 +2895,7 @@ static int rdt_get_tree(struct fs_context *fc)
 		kernfs_remove(kn_mondata);
 out_mongrp:
 	if (resctrl_arch_mon_capable()) {
+		mon_put_kn_priv();
 		rdtgroup_unassign_cntrs(&rdtgroup_default);
 		kernfs_remove(kn_mongrp);
 	}