mm/mmu_context, sched/core: Fix mmu_context.h assumption

mm/mmu_context, sched/core: Fix mmu_context.h assumption

commit 8efd755ac2fe262d4c8d5c9bbe054bb67dae93da upstream.

Some architectures (such as Alpha) rely on include/linux/sched.h definitions
in their mmu_context.h files.

So include sched.h before mmu_context.h.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit dfe513a4e8ddde75ffc6abd3f139c5d65bf925d7)
Orabug: 27333760
CVE: CVE-2017-5754
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>