mm: rename CONFIG_BALLOON_COMPACTION to CONFIG_BALLOON_MIGRATION

While compaction depends on migration, the other direction is not the
case.  So let's make it clearer that this is all about migration of
balloon pages.

Adjust all comments/docs in the core to talk about "migration" instead of
"compaction".

While at it add some "/* CONFIG_BALLOON_MIGRATION */".

Link: https://lkml.kernel.org/r/20260119230133.3551867-23-david@kernel.org
Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Eugenio Pérez <eperezma@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jerrin Shaji George <jerrin.shaji-george@broadcom.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

5 files changed, 12 insertions, 12 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index c5374f3cf1c8..cd6896c1ba7d 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -597,8 +597,8 @@ config MEMORY_BALLOON
 	bool
 
 #
-# support for memory balloon compaction
-config BALLOON_COMPACTION
+# support for memory balloon page migration
+config BALLOON_MIGRATION
 	bool "Allow for balloon memory migration"
 	default y
 	depends on MIGRATION && MEMORY_BALLOON
diff --git a/mm/balloon.c b/mm/balloon.c
index 0f068b97e5d8..96a8f1e20bc6 100644
--- a/mm/balloon.c
+++ b/mm/balloon.c
@@ -29,7 +29,7 @@ static void balloon_page_insert(struct balloon_dev_info *balloon,
 {
 	lockdep_assert_held(&balloon_pages_lock);
 	__SetPageOffline(page);
-	if (IS_ENABLED(CONFIG_BALLOON_COMPACTION)) {
+	if (IS_ENABLED(CONFIG_BALLOON_MIGRATION)) {
 		SetPageMovableOps(page);
 		set_page_private(page, (unsigned long)balloon);
 	}
@@ -46,7 +46,7 @@ static void balloon_page_insert(struct balloon_dev_info *balloon,
 static void balloon_page_finalize(struct page *page)
 {
 	lockdep_assert_held(&balloon_pages_lock);
-	if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
+	if (IS_ENABLED(CONFIG_BALLOON_MIGRATION))
 		set_page_private(page, 0);
 	/* PageOffline is sticky until the page is freed to the buddy. */
 }
@@ -148,7 +148,7 @@ struct page *balloon_page_alloc(void)
 {
 	gfp_t gfp_flags = __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
 
-	if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
+	if (IS_ENABLED(CONFIG_BALLOON_MIGRATION))
 		gfp_flags |= GFP_HIGHUSER_MOVABLE;
 	else
 		gfp_flags |= GFP_HIGHUSER;
@@ -227,7 +227,7 @@ struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
 }
 EXPORT_SYMBOL_GPL(balloon_page_dequeue);
 
-#ifdef CONFIG_BALLOON_COMPACTION
+#ifdef CONFIG_BALLOON_MIGRATION
 static struct balloon_dev_info *balloon_page_device(struct page *page)
 {
 	return (struct balloon_dev_info *)page_private(page);
@@ -341,4 +341,4 @@ static int __init balloon_init(void)
 }
 core_initcall(balloon_init);
 
-#endif /* CONFIG_BALLOON_COMPACTION */
+#endif /* CONFIG_BALLOON_MIGRATION */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 389989a28abe..bc805029da51 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -946,8 +946,8 @@ static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long start_pfn
  * We rely on "present pages" instead of "managed pages", as the latter is
  * highly unreliable and dynamic in virtualized environments, and does not
  * consider boot time allocations. For example, memory ballooning adjusts the
- * managed pages when inflating/deflating the balloon, and balloon compaction
- * can even migrate inflated pages between zones.
+ * managed pages when inflating/deflating the balloon, and balloon page
+ * migration can even migrate inflated pages between zones.
  *
  * Using "present pages" is better but some things to keep in mind are:
  *
diff --git a/mm/migrate.c b/mm/migrate.c
index 4750a2ba15fe..1bf2cf8c44dd 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -88,7 +88,7 @@ static const struct movable_operations *page_movable_ops(struct page *page)
 	 * back to the buddy.
 	 */
 	if (PageOffline(page))
-		/* Only balloon compaction sets PageOffline pages movable. */
+		/* Only balloon page migration sets PageOffline pages movable. */
 		return offline_movable_ops;
 	if (PageZsmalloc(page))
 		return zsmalloc_movable_ops;
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 6ae8891c9693..e96a344ab597 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1422,9 +1422,9 @@ const char * const vmstat_text[] = {
 #ifdef CONFIG_MEMORY_BALLOON
 	[I(BALLOON_INFLATE)]			= "balloon_inflate",
 	[I(BALLOON_DEFLATE)]			= "balloon_deflate",
-#ifdef CONFIG_BALLOON_COMPACTION
+#ifdef CONFIG_BALLOON_MIGRATION
 	[I(BALLOON_MIGRATE)]			= "balloon_migrate",
-#endif
+#endif /* CONFIG_BALLOON_MIGRATION */
 #endif /* CONFIG_MEMORY_BALLOON */
 #ifdef CONFIG_DEBUG_TLBFLUSH
 	[I(NR_TLB_REMOTE_FLUSH)]		= "nr_tlb_remote_flush",