[PATCH -next v2 5/7] mm/mglru: extend lru_gen_shrink_lruvec to support root reclaim

[Chen Ridong <chenridong@huaweicloud.com>]

From: Chen Ridong <chenridong@huawei.com>

The upcoming patch will integrate shrink_many and shrink_node_memcgs.
Currently, lru_gen_shrink_lruvec only supports non-root reclaim invoked
from shrink_node_memcgs. This patch extends it to also handle root reclaim.

Since the initial setup for root reclaim is already completed in
lru_gen_shrink_node, we can simply call try_to_shrink_lruvec within
lru_gen_shrink_lruvec for root reclaim.

Signed-off-by: Chen Ridong <chenridong@huawei.com>
---
 mm/vmscan.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index e55c7835cab5..3a266f6456af 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4820,7 +4820,15 @@ static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc
 {
 	struct blk_plug plug;
 
-	VM_WARN_ON_ONCE(root_reclaim(sc));
+	/*
+	 * For root reclaim, the initial setup has already been completed externally;
+	 * proceed directly with the shrinking operation.
+	 */
+	if (root_reclaim(sc)) {
+		try_to_shrink_lruvec(lruvec, sc);
+		return;
+	}
+
 	VM_WARN_ON_ONCE(!sc->may_writepage || !sc->may_unmap);
 
 	lru_add_drain();
-- 
2.34.1