[PATCH 1/1] mm/migrate: de-duplicate migrate_reason strings

John Hubbard
2021-09-22T04:18:14Z

In order to remove the need to manually keep three different files in
synch, provide a common definition of the mapping between enum
migrate_reason, and the associated strings for each enum item.

1. Use the tracing system's mapping of enums to strings, by redefining
and reusing the MIGRATE_REASON and supporting macros, and using that to
populate the string array in mm/debug.c.

2. Move enum migrate_reason to migrate_mode.h. This is not strictly
necessary for this patch, but migrate mode and migrate reason go
together, so this will slightly clarify things.

Cc: Weizhao Ouyang <o451686892@gmail.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
include/linux/migrate.h | 19 +------------------
include/linux/migrate_mode.h | 13 +++++++++++++
mm/debug.c | 20 +++++++++++---------
3 files changed, 25 insertions(+), 27 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index c8077e936691..3d154fe03c96 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -19,24 +19,7 @@ struct migration_target_control;
*/
#define MIGRATEPAGE_SUCCESS 0

-/*
- * Keep sync with:
- * - macro MIGRATE_REASON in include/trace/events/migrate.h
- * - migrate_reason_names[MR_TYPES] in mm/debug.c
- */
-enum migrate_reason {
- MR_COMPACTION,
- MR_MEMORY_FAILURE,
- MR_MEMORY_HOTPLUG,
- MR_SYSCALL, /* also applies to cpusets */
- MR_MEMPOLICY_MBIND,
- MR_NUMA_MISPLACED,
- MR_CONTIG_RANGE,
- MR_LONGTERM_PIN,
- MR_DEMOTION,
- MR_TYPES
-};
-
+/* Defined in mm/debug.c: */
extern const char *migrate_reason_names[MR_TYPES];

#ifdef CONFIG_MIGRATION
diff --git a/include/linux/migrate_mode.h b/include/linux/migrate_mode.h
index 883c99249033..f37cc03f9369 100644
--- a/include/linux/migrate_mode.h
+++ b/include/linux/migrate_mode.h
@@ -19,4 +19,17 @@ enum migrate_mode {
MIGRATE_SYNC_NO_COPY,
};

+enum migrate_reason {
+ MR_COMPACTION,
+ MR_MEMORY_FAILURE,
+ MR_MEMORY_HOTPLUG,
+ MR_SYSCALL, /* also applies to cpusets */
+ MR_MEMPOLICY_MBIND,
+ MR_NUMA_MISPLACED,
+ MR_CONTIG_RANGE,
+ MR_LONGTERM_PIN,
+ MR_DEMOTION,
+ MR_TYPES
+};
+
#endif /* MIGRATE_MODE_H_INCLUDED */
diff --git a/mm/debug.c b/mm/debug.c
index fae0f81ad831..4333b6784a20 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -16,17 +16,19 @@
#include <linux/ctype.h>

#include "internal.h"
+#include <trace/events/migrate.h>
+
+/*
+ * Define EM() and EMe() so that MIGRATE_REASON from trace/events/migrate.h can
+ * be used to populate migrate_reason_names[].
+ */
+#undef EM
+#undef EMe
+#define EM(a, b) b,
+#define EMe(a, b) b

const char *migrate_reason_names[MR_TYPES] = {
- "compaction",
- "memory_failure",
- "memory_hotplug",
- "syscall_or_cpuset",
- "mempolicy_mbind",
- "numa_misplaced",
- "contig_range",
- "longterm_pin",
- "demotion",
+ MIGRATE_REASON
};

const struct trace_print_flags pageflag_names[] = {
--
2.33.0