mm: migrate: Add a tracepoint for migrate_pages

The pgmigrate_success and pgmigrate_fail vmstat counters tells the user
about migration activity but not the type or the reason. This patch adds
a tracepoint to identify the type of page migration and why the page is
being migrated.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>

8 files changed, 82 insertions, 10 deletions

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index ce7e6671968b..9d1c159e2427 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -7,6 +7,15 @@
 
 typedef struct page *new_page_t(struct page *, unsigned long private, int **);
 
+enum migrate_reason {
+        MR_COMPACTION,
+        MR_MEMORY_FAILURE,
+        MR_MEMORY_HOTPLUG,
+        MR_SYSCALL,             /* also applies to cpusets */
+        MR_MEMPOLICY_MBIND,
+        MR_CMA
+};
+
 #ifdef CONFIG_MIGRATION
 
 extern void putback_lru_pages(struct list_head *l);
@@ -14,7 +23,7 @@ extern int migrate_page(struct address_space *,
                         struct page *, struct page *, enum migrate_mode);
 extern int migrate_pages(struct list_head *l, new_page_t x,
                         unsigned long private, bool offlining,
-                        enum migrate_mode mode);
+                        enum migrate_mode mode, int reason);
 extern int migrate_huge_page(struct page *, new_page_t x,
                         unsigned long private, bool offlining,
                         enum migrate_mode mode);
@@ -35,7 +44,7 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping,
 static inline void putback_lru_pages(struct list_head *l) {}
 static inline int migrate_pages(struct list_head *l, new_page_t x,
                 unsigned long private, bool offlining,
-                enum migrate_mode mode) { return -ENOSYS; }
+                enum migrate_mode mode, int reason) { return -ENOSYS; }
 static inline int migrate_huge_page(struct page *page, new_page_t x,
                 unsigned long private, bool offlining,
                 enum migrate_mode mode) { return -ENOSYS; }
diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h
new file mode 100644
index 000000000000..ec2a6ccfd7e5
--- /dev/null
+++ b/include/trace/events/migrate.h
@@ -0,0 +1,51 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM migrate
+
+#if !defined(_TRACE_MIGRATE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MIGRATE_H
+
+#define MIGRATE_MODE                                            \
+        {MIGRATE_ASYNC,         "MIGRATE_ASYNC"},               \
+        {MIGRATE_SYNC_LIGHT,    "MIGRATE_SYNC_LIGHT"},          \
+        {MIGRATE_SYNC,          "MIGRATE_SYNC"}         
+
+#define MIGRATE_REASON                                          \
+        {MR_COMPACTION,         "compaction"},                  \
+        {MR_MEMORY_FAILURE,     "memory_failure"},              \
+        {MR_MEMORY_HOTPLUG,     "memory_hotplug"},              \
+        {MR_SYSCALL,            "syscall_or_cpuset"},           \
+        {MR_MEMPOLICY_MBIND,    "mempolicy_mbind"},             \
+        {MR_CMA,                "cma"}
+
+TRACE_EVENT(mm_migrate_pages,
+
+        TP_PROTO(unsigned long succeeded, unsigned long failed,
+                 enum migrate_mode mode, int reason),
+
+        TP_ARGS(succeeded, failed, mode, reason),
+
+        TP_STRUCT__entry(
+                __field(        unsigned long,          succeeded)
+                __field(        unsigned long,          failed)
+                __field(        enum migrate_mode,      mode)
+                __field(        int,                    reason)
+        ),
+
+        TP_fast_assign(
+                __entry->succeeded      = succeeded;
+                __entry->failed         = failed;
+                __entry->mode           = mode;
+                __entry->reason         = reason;
+        ),
+
+        TP_printk("nr_succeeded=%lu nr_failed=%lu mode=%s reason=%s",
+                __entry->succeeded,
+                __entry->failed,
+                __print_symbolic(__entry->mode, MIGRATE_MODE),
+                __print_symbolic(__entry->reason, MIGRATE_REASON))
+);
+
+#endif /* _TRACE_MIGRATE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/mm/compaction.c b/mm/compaction.c
index 00ad88395216..2c077a78487c 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -990,7 +990,8 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
                 nr_migrate = cc->nr_migratepages;
                 err = migrate_pages(&cc->migratepages, compaction_alloc,
                                 (unsigned long)cc, false,
-                                cc->sync ? MIGRATE_SYNC_LIGHT : MIGRATE_ASYNC);
+                                cc->sync ? MIGRATE_SYNC_LIGHT : MIGRATE_ASYNC,
+                                MR_COMPACTION);
                 update_nr_listpages(cc);
                 nr_remaining = cc->nr_migratepages;
 
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 6c5899b9034a..ddb68a169e45 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1558,7 +1558,8 @@ int soft_offline_page(struct page *page, int flags)
                                             page_is_file_cache(page));
                 list_add(&page->lru, &pagelist);
                 ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL,
-                                                        false, MIGRATE_SYNC);
+                                                        false, MIGRATE_SYNC,
+                                                        MR_MEMORY_FAILURE);
                 if (ret) {
                         putback_lru_pages(&pagelist);
                         pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index e4eeacae2b91..e598bd15c041 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -812,7 +812,8 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
                  * migrate_pages returns # of failed pages.
                  */
                 ret = migrate_pages(&source, alloc_migrate_target, 0,
-                                                        true, MIGRATE_SYNC);
+                                                        true, MIGRATE_SYNC,
+                                                        MR_MEMORY_HOTPLUG);
                 if (ret)
                         putback_lru_pages(&source);
         }
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d04a8a54c294..66e90ecc2350 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -961,7 +961,8 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
 
         if (!list_empty(&pagelist)) {
                 err = migrate_pages(&pagelist, new_node_page, dest,
-                                                        false, MIGRATE_SYNC);
+                                                        false, MIGRATE_SYNC,
+                                                        MR_SYSCALL);
                 if (err)
                         putback_lru_pages(&pagelist);
         }
@@ -1202,7 +1203,8 @@ static long do_mbind(unsigned long start, unsigned long len,
                 if (!list_empty(&pagelist)) {
                         nr_failed = migrate_pages(&pagelist, new_vma_page,
                                                 (unsigned long)vma,
-                                                false, MIGRATE_SYNC);
+                                                false, MIGRATE_SYNC,
+                                                MR_MEMPOLICY_MBIND);
                         if (nr_failed)
                                 putback_lru_pages(&pagelist);
                 }
diff --git a/mm/migrate.c b/mm/migrate.c
index 04687f69cc17..27be9c923dc1 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -38,6 +38,9 @@
 
 #include <asm/tlbflush.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/migrate.h>
+
 #include "internal.h"
 
 /*
@@ -958,7 +961,7 @@ out:
  */
 int migrate_pages(struct list_head *from,
                 new_page_t get_new_page, unsigned long private, bool offlining,
-                enum migrate_mode mode)
+                enum migrate_mode mode, int reason)
 {
         int retry = 1;
         int nr_failed = 0;
@@ -1004,6 +1007,8 @@ out:
                 count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);
         if (nr_failed)
                 count_vm_events(PGMIGRATE_FAIL, nr_failed);
+        trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason);
+
         if (!swapwrite)
                 current->flags &= ~PF_SWAPWRITE;
 
@@ -1145,7 +1150,8 @@ set_status:
         err = 0;
         if (!list_empty(&pagelist)) {
                 err = migrate_pages(&pagelist, new_page_node,
-                                (unsigned long)pm, 0, MIGRATE_SYNC);
+                                (unsigned long)pm, 0, MIGRATE_SYNC,
+                                MR_SYSCALL);
                 if (err)
                         putback_lru_pages(&pagelist);
         }
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7bb35ac0964a..5953dc2d196f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5707,7 +5707,8 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
 
                 ret = migrate_pages(&cc->migratepages,
                                     alloc_migrate_target,
-                                    0, false, MIGRATE_SYNC);
+                                    0, false, MIGRATE_SYNC,
+                                    MR_CMA);
         }
 
         putback_lru_pages(&cc->migratepages);