freezer: take kernel_execve into consideration

Kernel threads can become userland processes by calling kernel_execve().

In particular, this may happen right after the try_to_freeze_tasks()
called with FREEZER_USER_SPACE has returned, so try_to_freeze_tasks()
needs to take userspace processes into consideration even if it is
called with FREEZER_KERNEL_THREADS.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/power/process.c

@@ -120,7 +120,7 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space)
 				cancel_freezing(p);
 				continue;
 			}
-			if (is_user_space(p) == !freeze_user_space)
+			if (freeze_user_space && !is_user_space(p))
 				continue;
 
 			freeze_process(p);
@@ -147,7 +147,7 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space)
 				TIMEOUT / HZ, todo);
 		read_lock(&tasklist_lock);
 		do_each_thread(g, p) {
-			if (is_user_space(p) == !freeze_user_space)
+			if (freeze_user_space && !is_user_space(p))
 				continue;
 
 			task_lock(p);