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mm: rename CONFIG_BALLOON_COMPACTION to CONFIG_BALLOON_MIGRATION

Browse source 
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>
This commit is contained in:
David Hildenbrand (Red Hat) 2026-01-20 00:01:30 +01:00 • committed by Andrew Morton
parent 7cf3318a25
commit cd8e95d80b
11 changed files with 35 additions and 35 deletions
Download patch file Download diff file Expand all files Collapse all files

8
Documentation/admin-guide/mm/memory-hotplug.rst
View file

@ -603,11 +603,11 @@ ZONE_MOVABLE, especially when fine-tuning zone ratios:
memory for metadata and page tables in the direct map; having a lot of offline
memory blocks is not a typical case, though.
- Memory ballooning without balloon compaction is incompatible with
ZONE_MOVABLE. Only some implementations, such as virtio-balloon and
pseries CMM, fully support balloon compaction.
- Memory ballooning without support for balloon memory migration is incompatible
with ZONE_MOVABLE. Only some implementations, such as virtio-balloon and
pseries CMM, fully support balloon memory migration.
Further, the CONFIG_BALLOON_COMPACTION kernel configuration option might be
Further, the CONFIG_BALLOON_MIGRATION kernel configuration option might be
disabled. In that case, balloon inflation will only perform unmovable
allocations and silently create a zone imbalance, usually triggered by
inflation requests from the hypervisor.

8
arch/powerpc/platforms/pseries/cmm.c
View file

@ -494,7 +494,7 @@ static struct notifier_block cmm_mem_nb = {
.priority = CMM_MEM_HOTPLUG_PRI
};
#ifdef CONFIG_BALLOON_COMPACTION
#ifdef CONFIG_BALLOON_MIGRATION
static int cmm_migratepage(struct balloon_dev_info *b_dev_info,
struct page *newpage, struct page *page,
enum migrate_mode mode)
@ -520,10 +520,10 @@ static int cmm_migratepage(struct balloon_dev_info *b_dev_info,
plpar_page_set_active(page);
return 0;
}
#else /* CONFIG_BALLOON_COMPACTION */
#else /* CONFIG_BALLOON_MIGRATION */
int cmm_migratepage(struct balloon_dev_info *b_dev_info, struct page *newpage,
struct page *page, enum migrate_mode mode);
#endif /* CONFIG_BALLOON_COMPACTION */
#endif /* CONFIG_BALLOON_MIGRATION */
/**
* cmm_init - Module initialization
@ -540,7 +540,7 @@ static int cmm_init(void)
balloon_devinfo_init(&b_dev_info);
b_dev_info.adjust_managed_page_count = true;
if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
if (IS_ENABLED(CONFIG_BALLOON_MIGRATION))
b_dev_info.migratepage = cmm_migratepage;
rc = register_oom_notifier(&cmm_oom_nb);

8
drivers/misc/vmw_balloon.c
View file

@ -1719,7 +1719,7 @@ static inline void vmballoon_debugfs_exit(struct vmballoon *b)
#endif /* CONFIG_DEBUG_FS */
#ifdef CONFIG_BALLOON_COMPACTION
#ifdef CONFIG_BALLOON_MIGRATION
/**
* vmballoon_migratepage() - migrates a balloon page.
* @b_dev_info: balloon device information descriptor.
@ -1803,11 +1803,11 @@ out_unlock:
up_read(&b->conf_sem);
return ret;
}
#else /* CONFIG_BALLOON_COMPACTION */
#else /* CONFIG_BALLOON_MIGRATION */
int vmballoon_migratepage(struct balloon_dev_info *b_dev_info,
struct page *newpage, struct page *page,
enum migrate_mode mode);
#endif /* CONFIG_BALLOON_COMPACTION */
#endif /* CONFIG_BALLOON_MIGRATION */
static int __init vmballoon_init(void)
{
@ -1827,7 +1827,7 @@ static int __init vmballoon_init(void)
return error;
balloon_devinfo_init(&balloon.b_dev_info);
if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
if (IS_ENABLED(CONFIG_BALLOON_MIGRATION))
balloon.b_dev_info.migratepage = vmballoon_migratepage;
INIT_LIST_HEAD(&balloon.huge_pages);

6
drivers/virtio/virtio_balloon.c
View file

@ -802,7 +802,7 @@ static void report_free_page_func(struct work_struct *work)
}
}
#ifdef CONFIG_BALLOON_COMPACTION
#ifdef CONFIG_BALLOON_MIGRATION
/*
* virtballoon_migratepage - perform the balloon page migration on behalf of
* a compaction thread. (called under page lock)
@ -851,7 +851,7 @@ static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
mutex_unlock(&vb->balloon_lock);
return 0;
}
#endif /* CONFIG_BALLOON_COMPACTION */
#endif /* CONFIG_BALLOON_MIGRATION */
static unsigned long shrink_free_pages(struct virtio_balloon *vb,
unsigned long pages_to_free)
@ -948,7 +948,7 @@ static int virtballoon_probe(struct virtio_device *vdev)
if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
vb->vb_dev_info.adjust_managed_page_count = true;
#ifdef CONFIG_BALLOON_COMPACTION
#ifdef CONFIG_BALLOON_MIGRATION
vb->vb_dev_info.migratepage = virtballoon_migratepage;
#endif
if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {

12
include/linux/balloon.h
View file

@ -22,9 +22,9 @@
*
* As the page isolation scanning step a compaction thread does is a lockless
* procedure (from a page standpoint), it might bring some racy situations while
* performing balloon page compaction. In order to sort out these racy scenarios
* and safely perform balloon's page compaction and migration we must, always,
* ensure following these simple rules:
* performing balloon page migration. In order to sort out these racy scenarios
* and safely perform balloon's page migration we must, always, ensure following
* these simple rules:
*
* i. Inflation/deflation must set/clear page->private under the
* balloon_pages_lock
@ -45,10 +45,10 @@
/*
* Balloon device information descriptor.
* This struct is used to allow the common balloon compaction interface
* This struct is used to allow the common balloon page migration interface
* procedures to find the proper balloon device holding memory pages they'll
* have to cope for page compaction / migration, as well as it serves the
* balloon driver as a page book-keeper for its registered balloon devices.
* have to cope for page migration, as well as it serves the balloon driver as
* a page book-keeper for its registered balloon devices.
*/
struct balloon_dev_info {
unsigned long isolated_pages; /* # of isolated pages for migration */

4
include/linux/vm_event_item.h
View file

@ -125,9 +125,9 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
#ifdef CONFIG_MEMORY_BALLOON
BALLOON_INFLATE,
BALLOON_DEFLATE,
#ifdef CONFIG_BALLOON_COMPACTION
#ifdef CONFIG_BALLOON_MIGRATION
BALLOON_MIGRATE,
#endif
#endif /* CONFIG_BALLOON_MIGRATION */
#endif
#ifdef CONFIG_DEBUG_TLBFLUSH
NR_TLB_REMOTE_FLUSH, /* cpu tried to flush others' tlbs */

4
mm/Kconfig
View file

@ -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

10
mm/balloon.c
View file

@ -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 */

4
mm/memory_hotplug.c
View file

@ -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:
*

2
mm/migrate.c
View file

@ -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;

4
mm/vmstat.c
View file

@ -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",