mm/kconfig: make BALLOON_COMPACTION depend on MIGRATION

Migration support for balloon memory depends on MIGRATION not COMPACTION.
Compaction is simply another user of page migration.

The last dependency on compaction.c was effectively removed with commit
3d388584d599 ("mm: convert "movable" flag in page->mapping to a page
flag").  Ever since, everything for handling movable_ops page migration
resides in core migration code.

So let's change the dependency and adjust the description + help text.

We'll rename BALLOON_COMPACTION separately next.

Link: https://lkml.kernel.org/r/20260119230133.3551867-22-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>

diff --git a/mm/Kconfig b/mm/Kconfig
index 5f4d6e5b5715903b169bb6f3cc4f7b59e346c73e..c5374f3cf1c81dacab00c083fca04d6bf9255ccb 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -599,17 +599,14 @@ config MEMORY_BALLOON
 #
 # support for memory balloon compaction
 config BALLOON_COMPACTION
-       bool "Allow for balloon memory compaction/migration"
+       bool "Allow for balloon memory migration"
        default y
-       depends on COMPACTION && MEMORY_BALLOON
-       help
-         Memory fragmentation introduced by ballooning might reduce
-         significantly the number of 2MB contiguous memory blocks that can be
-         used within a guest, thus imposing performance penalties associated
-         with the reduced number of transparent huge pages that could be used
-         by the guest workload. Allowing the compaction & migration for memory
-         pages enlisted as being part of memory balloon devices avoids the
-         scenario aforementioned and helps improving memory defragmentation.
+       depends on MIGRATION && MEMORY_BALLOON
+       help
+         Allow for migration of pages inflated in a memory balloon such that
+         they can be allocated from memory areas only available for movable
+         allocations (e.g., ZONE_MOVABLE, CMA) and such that they can be
+         migrated for memory defragmentation purposes by memory compaction.
 
 #
 # support for memory compaction