mm/balloon_compaction: centralize adjust_managed_page_count() handling

Let's centralize it, by allowing for the driver to enable this handling
through a new flag (bool for now) in the balloon device info.

Note that we now adjust the counter when adding/removing a page into the
balloon list: when removing a page to deflate it, it will now happen
before the driver communicated with hypervisor, not afterwards.

This shouldn't make a difference in practice.

Link: https://lkml.kernel.org/r/20260119230133.3551867-7-david@kernel.org
Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org>
Acked-by: Liam R. Howlett <Liam.Howlett@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: Lorenzo Stoakes <lorenzo.stoakes@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>

1 files changed, 1 insertions, 12 deletions

diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
index 15f873f733a4..7fd8b3d7e763 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -165,7 +165,6 @@ static long cmm_alloc_pages(long nr)
 
 		balloon_page_enqueue(&b_dev_info, page);
 		atomic_long_inc(&loaned_pages);
-		adjust_managed_page_count(page, -1);
 		nr--;
 	}
 
@@ -190,7 +189,6 @@ static long cmm_free_pages(long nr)
 		if (!page)
 			break;
 		plpar_page_set_active(page);
-		adjust_managed_page_count(page, 1);
 		__free_page(page);
 		atomic_long_dec(&loaned_pages);
 		nr--;
@@ -516,16 +514,6 @@ static int cmm_migratepage(struct balloon_dev_info *b_dev_info,
 	}
 
 	/*
-	 * When we migrate a page to a different zone, we have to fixup the
-	 * count of both involved zones as we adjusted the managed page count
-	 * when inflating.
-	 */
-	if (page_zone(page) != page_zone(newpage)) {
-		adjust_managed_page_count(page, 1);
-		adjust_managed_page_count(newpage, -1);
-	}
-
-	/*
 	 * activate/"deflate" the old page. We ignore any errors just like the
 	 * other callers.
 	 */
@@ -551,6 +539,7 @@ static int cmm_init(void)
 		return -EOPNOTSUPP;
 
 	balloon_devinfo_init(&b_dev_info);
+	b_dev_info.adjust_managed_page_count = true;
 	if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
 		b_dev_info.migratepage = cmm_migratepage;