Disappearing dentries in linux kernel after reboot

Question

I am trying to create chunk of vfs by kernel, this function create directories in my module. My code looks:

struct dentry   *dentry;
struct path     path;
int             err, lookup;

lookup = LOOKUP_DIRECTORY | LOOKUP_REVAL;
mode |= S_IFDIR;

dentry = kern_path_create(AT_FDCWD, name, &path, lookup);
if (IS_ERR(dentry))
{
    return PTR_ERR(dentry);
}

err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
if (err)
{
    
}

done_path_create(&path, dentry);
return err;

Before reboot

f1 <- dir

f2 <- dir (subdir f1)

f3 <- dir (subdir f1)

After reboot vfs tree disappear in struct dentry.

f1 <- dir

To get this output i used:

err = kern_path(FULL_MAIN_DIR_NAME, LOOKUP_FOLLOW, &tmp_root);
     printk(KERN_DEBUG "%s <- dir\n",tmp_root.dentry->d_name.name );

    list_for_each_entry(tmp_dentry, &tmp_root.dentry->d_subdirs, d_child)
    {
        if (tmp_dentry->d_name.name)
        {
            printk(KERN_INFO "%s <- dir (subdir f1)\n", tmp_dentry->d_name.name);
        }    
    }

But directories are still present in system, i can use them normally. In other hand, struct inode_operations attached to them are cleared too. Anybody know how to solve this problem?