[PATCH v2] mm/balloon: expose per-node balloon pages in node meminfo

[Hao Ge <hao.ge@linux.dev>]

Commit 835de37603ef ("meminfo: add a per node counter for balloon
drivers") added NR_BALLOON_PAGES and exposed it in /proc/meminfo.
However, the per-node view at /sys/devices/system/node/nodeX/meminfo
was not updated, even though the counter is already tracked per-node.

Add it to node_read_meminfo() so users can see balloon usage per
NUMA node without having to parse the raw vmstat file.

Signed-off-by: Hao Ge <hao.ge@linux.dev>
---
v2: Move Balloon field after Unaccepted to match /proc/meminfo ordering
    (suggested by David Hildenbrand)
---
 drivers/base/node.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index d7647d077b66..85c20aa3c7f2 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -523,6 +523,7 @@ static ssize_t node_read_meminfo(struct device *dev,
 #ifdef CONFIG_UNACCEPTED_MEMORY
 			     "Node %d Unaccepted:     %8lu kB\n"
 #endif
+			     "Node %d Balloon:        %8lu kB\n"
 			     ,
 			     nid, K(node_page_state(pgdat, NR_FILE_DIRTY)),
 			     nid, K(node_page_state(pgdat, NR_WRITEBACK)),
@@ -556,6 +557,8 @@ static ssize_t node_read_meminfo(struct device *dev,
 			     ,
 			     nid, K(sum_zone_node_page_state(nid, NR_UNACCEPTED))
 #endif
+			     ,
+			     nid, K(node_page_state(pgdat, NR_BALLOON_PAGES))
 			    );
 	len += hugetlb_report_node_meminfo(buf, len, nid);
 	return len;
-- 
2.25.1