Re: [PATCH v2 5/9] mm, page_owner: track and print last migrate reason

[Vlastimil Babka <vbabka@suse.cz>]

On 11/25/2015 09:13 AM, Joonsoo Kim wrote:
>> +	if (page_ext->last_migrate_reason != -1) {
>> +		ret += snprintf(kbuf + ret, count - ret,
>> +			"Page has been migrated, last migrate reason: %s\n",
>> +			migrate_reason_names[page_ext->last_migrate_reason]);
>> +		if (ret >= count)
>> +			goto err;
>> +	}
>> +
> 
> migrate_reason_names is defined if CONFIG_MIGRATION is enabled so
> it would cause build failure in case of !CONFIG_MIGRATION and
> CONFIG_PAGE_OWNER.
> 
> Thanks.

Ugh right, linking gives warnings... Thanks.
I think instead of adding #ifdefs here, let's move migrate_reason_names to
mm/debug.c as we gradually do with these things. Also enum
migrate_reason is defined regardless of CONFIG_MIGRATION, so match that
for migrate_reason_names as well.

------8<------
>From 7b650fd613ed382aaa6f11f4b779e883a6af10aa Mon Sep 17 00:00:00 2001
From: Vlastimil Babka <vbabka@suse.cz>
Date: Thu, 26 Nov 2015 11:31:09 +0100
Subject: mm, page_owner: track and print last migrate reason-fix

Move migrate_reason_names from mm/migrate.c to mm/debug.c so that link doesn't
warn with CONFIG_MIGRATION disabled.

---
 include/linux/migrate.h |  2 +-
 mm/debug.c              | 11 +++++++++++
 mm/migrate.c            | 10 ----------
 3 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index ab92a8cf4c93..8fdc033e527a 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -27,7 +27,7 @@ enum migrate_reason {
 	MR_TYPES
 };
 
-/* In mm/migrate.c; also keep sync with include/trace/events/migrate.h */
+/* In mm/debug.c; also keep sync with include/trace/events/migrate.h */
 extern char * migrate_reason_names[MR_TYPES];
 
 #ifdef CONFIG_MIGRATION
diff --git a/mm/debug.c b/mm/debug.c
index d9718fc8377a..a4cd0c093ff6 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -9,6 +9,17 @@
 #include <linux/mm.h>
 #include <linux/trace_events.h>
 #include <linux/memcontrol.h>
+#include <linux/migrate.h>
+
+char *migrate_reason_names[MR_TYPES] = {
+	"compaction",
+	"memory_failure",
+	"memory_hotplug",
+	"syscall_or_cpuset",
+	"mempolicy_mbind",
+	"numa_misplaced",
+	"cma",
+};
 
 static const struct trace_print_flags pageflag_names[] = {
 	{1UL << PG_locked,		"locked"	},
diff --git a/mm/migrate.c b/mm/migrate.c
index 12e9ab9de446..1c11b73cd834 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -47,16 +47,6 @@
 
 #include "internal.h"
 
-char *migrate_reason_names[MR_TYPES] = {
-	"compaction",
-	"memory_failure",
-	"memory_hotplug",
-	"syscall_or_cpuset",
-	"mempolicy_mbind",
-	"numa_misplaced",
-	"cma",
-};
-
 /*
  * migrate_prep() needs to be called before we start compiling a list of pages
  * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
-- 
2.6.3