The last_migrate_reason field uses -1 as a sentinel value to mean "no
migration has happened".  Replace the four bare -1 occurrences by
adding a proper MR_NEVER member to enum migrate_reason, defining a
corresponding "never_migrated" string in the MIGRATE_REASON trace
macro, and removing the local MIGRATE_REASON_NONE define.

No functional change.

Signed-off-by: Ye Liu <[email protected]>
---
 include/linux/migrate_mode.h   | 1 +
 include/trace/events/migrate.h | 3 ++-
 mm/page_owner.c                | 8 ++++----
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/include/linux/migrate_mode.h b/include/linux/migrate_mode.h
index 265c4328b36a..05102d4d2490 100644
--- a/include/linux/migrate_mode.h
+++ b/include/linux/migrate_mode.h
@@ -25,6 +25,7 @@ enum migrate_reason {
        MR_LONGTERM_PIN,
        MR_DEMOTION,
        MR_DAMON,
+       MR_NEVER,               /* page has never been migrated */
        MR_TYPES
 };
 
diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h
index cd01dd7b3640..11bc0aa14c7e 100644
--- a/include/trace/events/migrate.h
+++ b/include/trace/events/migrate.h
@@ -23,7 +23,8 @@
        EM( MR_CONTIG_RANGE,    "contig_range")                 \
        EM( MR_LONGTERM_PIN,    "longterm_pin")                 \
        EM( MR_DEMOTION,        "demotion")                     \
-       EMe(MR_DAMON,           "damon")
+       EM( MR_DAMON,           "damon")                        \
+       EMe(MR_NEVER,           "never_migrated")
 
 /*
  * First define the enums in the above macros to be exported to userspace
diff --git a/mm/page_owner.c b/mm/page_owner.c
index 342549891a8d..c2f43ab860eb 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -339,7 +339,7 @@ noinline void __set_page_owner(struct page *page, unsigned 
short order,
        depot_stack_handle_t handle;
 
        handle = save_stack(gfp_mask);
-       __update_page_owner_handle(page, handle, order, gfp_mask, -1,
+       __update_page_owner_handle(page, handle, order, gfp_mask, MR_NEVER,
                                   ts_nsec, current->pid, current->tgid,
                                   current->comm);
        inc_stack_record_count(handle, gfp_mask, 1 << order);
@@ -596,7 +596,7 @@ print_page_owner(char __user *buf, size_t count, unsigned 
long pfn,
        if (ret >= count)
                goto err;
 
-       if (page_owner->last_migrate_reason != -1) {
+       if (page_owner->last_migrate_reason != MR_NEVER) {
                ret += scnprintf(kbuf + ret, count - ret,
                        "Page has been migrated, last migrate reason: %s\n",
                        migrate_reason_names[page_owner->last_migrate_reason]);
@@ -667,7 +667,7 @@ void __dump_page_owner(const struct page *page)
                stack_depot_print(handle);
        }
 
-       if (page_owner->last_migrate_reason != -1)
+       if (page_owner->last_migrate_reason != MR_NEVER)
                pr_alert("page has been migrated, last migrate reason: %s\n",
                        migrate_reason_names[page_owner->last_migrate_reason]);
        page_ext_put(page_ext);
@@ -826,7 +826,7 @@ static void init_pages_in_zone(struct zone *zone)
 
                        /* Found early allocated page */
                        __update_page_owner_handle(page, early_handle, 0, 0,
-                                                  -1, local_clock(), 
current->pid,
+                                                  MR_NEVER, local_clock(), 
current->pid,
                                                   current->tgid, 
current->comm);
                        count++;
 ext_put_continue:
-- 
2.43.0


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