Merge: powerpc/64s: Fix VAS mm use after free

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/7682

Description: powerpc/64s: Fix VAS mm use after free

JIRA: https://issues.redhat.com/browse/RHEL-133781

Build Info: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=69625018

Tested: Verified Brew build test kernel RPMs and confirmed issue is resovled

Signed-off-by: Mamatha Inamdar <minamdar@redhat.com>

Approved-by: Steve Best <sbest@redhat.com>
Approved-by: Tony Camuso <tcamuso@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Patrick Talbert <ptalbert@redhat.com>

Author: ptalbert

arch/powerpc/platforms/powernv/vas-window.c

@@ -1310,8 +1310,8 @@ int vas_win_close(struct vas_window *vwin)
 	/* if send window, drop reference to matching receive window */
 	if (window->tx_win) {
 		if (window->user_win) {
-			put_vas_user_win_ref(&vwin->task_ref);
 			mm_context_remove_vas_window(vwin->task_ref.mm);
+			put_vas_user_win_ref(&vwin->task_ref);
 		}
 		put_rx_win(window->rxwin);
 	}

arch/powerpc/platforms/pseries/vas.c

@@ -540,8 +540,8 @@ static int vas_deallocate_window(struct vas_window *vwin)
 	vascaps[win->win_type].nr_open_windows--;
 	mutex_unlock(&vas_pseries_mutex);
 
-	put_vas_user_win_ref(&vwin->task_ref);
 	mm_context_remove_vas_window(vwin->task_ref.mm);
+	put_vas_user_win_ref(&vwin->task_ref);
 
 	kfree(win);
 	return 0;