From 02ec35963bc830f17c2aaa6f1008dcf7745c7c17 Mon Sep 17 00:00:00 2001
From: Nico Pache <npache@redhat.com>
Date: Fri, 14 Mar 2025 15:37:56 -0600
Subject: hv_balloon: update the NR_BALLOON_PAGES state

Update the NR_BALLOON_PAGES counter when pages are added to or removed
from the Hyper-V balloon.

Link: https://lkml.kernel.org/r/20250314213757.244258-4-npache@redhat.com
Signed-off-by: Nico Pache <npache@redhat.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Cc: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Juegren Gross <jgross@suse.com>
Cc: Kanchana P Sridhar <kanchana.p.sridhar@intel.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 drivers/hv/hv_balloon.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index fec2f18679e3..2b4080e51f97 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -1192,6 +1192,7 @@ static void free_balloon_pages(struct hv_dynmem_device *dm,
 		__ClearPageOffline(pg);
 		__free_page(pg);
 		dm->num_pages_ballooned--;
+		mod_node_page_state(page_pgdat(pg), NR_BALLOON_PAGES, -1);
 		adjust_managed_page_count(pg, 1);
 	}
 }
@@ -1221,6 +1222,7 @@ static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
 			return i * alloc_unit;
 
 		dm->num_pages_ballooned += alloc_unit;
+		mod_node_page_state(page_pgdat(pg), NR_BALLOON_PAGES, alloc_unit);
 
 		/*
 		 * If we allocatted 2M pages; split them so we
-- 
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