mm/mempolicy.c: forbid static or relative flags for local NUMA mode

The MPOL_F_STATIC_NODES and MPOL_F_RELATIVE_NODES flags are irrelevant
when setting them for MPOL_LOCAL NUMA memory policy via set_mempolicy or
mbind.

Return the "invalid argument" from set_mempolicy and mbind whenever any
of these flags is passed along with MPOL_LOCAL.

It is consistent with MPOL_PREFERRED passed with empty nodemask.

It slightly shortens the execution time in paths where these flags are
used e.g.  when trying to rebind the NUMA nodes for changes in cgroups
cpuset mems (mpol_rebind_preferred()) or when just printing the mempolicy
structure (/proc/PID/numa_maps).  Isolated tests done.

Link: http://lkml.kernel.org/r/20161027163037.4089-1-kwapulinski.piotr@gmail.comSigned-off-by: NPiotr Kwapulinski <kwapulinski.piotr@gmail.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Liang Chen <liangchen.linux@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Nathan Zimmer <nzimmer@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/mempolicy.c

@@ -276,7 +276,9 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags,
 				return ERR_PTR(-EINVAL);
 		}
 	} else if (mode == MPOL_LOCAL) {
-		if (!nodes_empty(*nodes))
+		if (!nodes_empty(*nodes) ||
+		    (flags & MPOL_F_STATIC_NODES) ||
+		    (flags & MPOL_F_RELATIVE_NODES))
 			return ERR_PTR(-EINVAL);
 		mode = MPOL_PREFERRED;
 	} else if (nodes_empty(*nodes))