+ mm-page_owner-use-migrate_reason_none-instead-of-1-for-last_migrate_reason.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/page_owner: use MIGRATE_REASON_NONE instead of -1 for last_migrate_reason
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-page_owner-use-migrate_reason_none-instead-of-1-for-last_migrate_reason.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_owner-use-migrate_reason_none-instead-of-1-for-last_migrate_reason.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Ye Liu <ye.liu@linux.dev>
Subject: mm/page_owner: use MIGRATE_REASON_NONE instead of -1 for last_migrate_reason
Date: Tue, 23 Jun 2026 14:52:27 +0800

The last_migrate_reason field uses -1 as a sentinel value to mean "no
migration has happened".  Replace the four bare -1 occurrences with a
local MIGRATE_REASON_NONE define so the intent is explicit and the magic
number is eliminated.

No functional change.

Link: https://lore.kernel.org/20260623065234.31866-3-ye.liu@linux.dev
Signed-off-by: Ye Liu <ye.liu@linux.dev>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_owner.c |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

--- a/mm/page_owner.c~mm-page_owner-use-migrate_reason_none-instead-of-1-for-last_migrate_reason
+++ a/mm/page_owner.c
@@ -21,6 +21,13 @@
  */
 #define PAGE_OWNER_STACK_DEPTH (16)
 
+/*
+ * Used to indicate that a page has never been migrated, as the valid
+ * migrate_reason values are non-negative enum members (MR_* in
+ * include/linux/migrate_mode.h).
+ */
+#define MIGRATE_REASON_NONE (-1)
+
 struct page_owner {
 	unsigned short order;
 	short last_migrate_reason;
@@ -339,7 +346,7 @@ noinline void __set_page_owner(struct pa
 	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, MIGRATE_REASON_NONE,
 				   ts_nsec, current->pid, current->tgid,
 				   current->comm);
 	inc_stack_record_count(handle, gfp_mask, 1 << order);
@@ -596,7 +603,7 @@ print_page_owner(char __user *buf, size_
 	if (ret >= count)
 		goto err;
 
-	if (page_owner->last_migrate_reason != -1) {
+	if (page_owner->last_migrate_reason != MIGRATE_REASON_NONE) {
 		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 +674,7 @@ void __dump_page_owner(const struct page
 		stack_depot_print(handle);
 	}
 
-	if (page_owner->last_migrate_reason != -1)
+	if (page_owner->last_migrate_reason != MIGRATE_REASON_NONE)
 		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 +833,7 @@ static void init_pages_in_zone(struct zo
 
 			/* Found early allocated page */
 			__update_page_owner_handle(page, early_handle, 0, 0,
-						   -1, local_clock(), current->pid,
+						   MIGRATE_REASON_NONE, local_clock(), current->pid,
 						   current->tgid, current->comm);
 			count++;
 ext_put_continue:
_

Patches currently in -mm which might be from ye.liu@linux.dev are

mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch
mm-page_owner-use-migrate_reason_none-instead-of-1-for-last_migrate_reason.patch
mm-page_owner-hoist-config_memcg-to-function-level-for-print_page_owner_memcg.patch
mm-page_owner-add-missing-newline-to-count_threshold-format-string.patch
mm-page_owner-move-free_ts_nsec-output-to-free-section-in-__dump_page_owner.patch
mm-page_owner-drop-redundant-page_owner-prefix-from-static-symbols.patch