[PATCH v3 2/4] mm: vmscan: propagate real error code from per-node proactive reclaim

[Ridong <ridong.chen@linux.dev>]

From: Ridong Chen <chenridong@xiaomi.com>

It has been observed that per-node proactive reclaim always returns
-EAGAIN when any error occurs. As discussed in the mailing list [1],
the interface should distinguish between cases where no reclaimable
memory is left and where another entity is concurrently using the
same interface. Propagate the real error code, consistent with how
memcg proactive reclaim handles errors.

[1] https://lore.kernel.org/all/20250717235604.2atyx2aobwowpge3@offworld/T/#m3514718be82a31b05726a49da9b61fbfc69a589e

Fixes: b980077899ea ("mm: introduce per-node proactive reclaim interface")
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Qi Zheng <qi.zheng@linux.dev>
Reviewed-by: Barry Song <baohua@kernel.org>
Signed-off-by: Ridong Chen <chenridong@xiaomi.com>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2c689682b952..4b62d6304c49 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -8023,7 +8023,7 @@ static ssize_t reclaim_store(struct device *dev,
 	int ret, nid = dev->id;
 
 	ret = user_proactive_reclaim((char *)buf, NULL, NODE_DATA(nid));
-	return ret ? -EAGAIN : count;
+	return ret ? ret : count;
 }
 
 static DEVICE_ATTR_WO(reclaim);
-- 
2.34.1