sched/headers: Prepare to remove the <linux/mm_types.h> dependency from <linux/sched.h>

Update code that relied on sched.h including various MM types for them.

This will allow us to remove the <linux/mm_types.h> include from <linux/sched.h>.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

lib/is_single_threaded.c

@@ -10,6 +10,7 @@
  * 2 of the Licence, or (at your option) any later version.
  */
 #include <linux/sched/signal.h>
+#include <linux/sched/mm.h>
 
 /*
  * Returns true if the task does not share ->mm with another thread/process.