After login successfully using Spring MVC still I can came back to login page

I'm first time implementing a web application using Java and Spring MVC. I also implemented login functionality for it. But, I'm facing a issue in that.

Issue: After successfully login my pare redirects to the target page but if I type the login page in browser then it displays login page again though the session is active.

Ideally it should go to the default target page. Bellow is my XML setting file. Thanks for any help in advance.

XML Config:

<http pattern="/resources/**" security="none" />
<http pattern="/admin/login" security="none" />
<http pattern="/admin/login/failed" security="none" />
<http pattern="/admin/login/invalidsession" security="none" />

<http auto-config="true"  use-expressions="false">
        <intercept-url pattern="/admin/**" access="ROLE_USER" />
        <form-login login-page="/admin/login" default-target-url="/admin/student" authentication-failure-url="/admin/login/failed" />
        <logout logout-success-url="/admin/login" delete-cookies="JSESSIONID" />
        <session-management session-fixation-protection="newSession" invalid-session-url="/admin/login/invalidsession">
        <concurrency-control max-sessions="1" error-if-maximum-exceeded="true" />
    </session-management>
</http>

<authentication-manager alias="authenticationManager">
        <authentication-provider>
                <user-service>
                        <user name="roul" password="roul" authorities="ROLE_USER" />
                </user-service>
        </authentication-provider>
</authentication-manager>