mm/migrate: rename migration reason MR_CMA to MR_CONTIG_RANGE

alloc_contig_range() initiates compaction and eventual migration for the
purpose of either CMA or HugeTLB allocations.  At present, the reason
code remains the same MR_CMA for either of these cases.  Let's make it
MR_CONTIG_RANGE which will appropriately reflect the reason code in both
these cases.

Link: http://lkml.kernel.org/r/20180202091518.18798-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/powerpc/mm/mmu_context_iommu.c

@@ -112,7 +112,7 @@ static int mm_iommu_move_page_from_cma(struct page *page)
 	put_page(page); /* Drop the gup reference */
 
 	ret = migrate_pages(&cma_migrate_pages, new_iommu_non_cma_page,
-				NULL, 0, MIGRATE_SYNC, MR_CMA);
+				NULL, 0, MIGRATE_SYNC, MR_CONTIG_RANGE);
 	if (ret) {
 		if (!list_empty(&cma_migrate_pages))
 			putback_movable_pages(&cma_migrate_pages);

include/linux/migrate.h

@@ -25,7 +25,7 @@ enum migrate_reason {
 	MR_SYSCALL,		/* also applies to cpusets */
 	MR_MEMPOLICY_MBIND,
 	MR_NUMA_MISPLACED,
-	MR_CMA,
+	MR_CONTIG_RANGE,
 	MR_TYPES
 };
 

include/trace/events/migrate.h

@@ -20,7 +20,7 @@
 	EM( MR_SYSCALL,		"syscall_or_cpuset")		\
 	EM( MR_MEMPOLICY_MBIND,	"mempolicy_mbind")		\
 	EM( MR_NUMA_MISPLACED,	"numa_misplaced")		\
-	EMe(MR_CMA,		"cma")
+	EMe(MR_CONTIG_RANGE,	"contig_range")
 
 /*
  * First define the enums in the above macros to be exported to userspace

mm/page_alloc.c

@@ -7591,7 +7591,7 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
 		cc->nr_migratepages -= nr_reclaimed;
 
 		ret = migrate_pages(&cc->migratepages, alloc_migrate_target,
-				    NULL, 0, cc->mode, MR_CMA);
+				    NULL, 0, cc->mode, MR_CONTIG_RANGE);
 	}
 	if (ret < 0) {
 		putback_movable_pages(&cc->migratepages);