From b27caeb46c9a8a0a023f90abe38fa2738856dc88 Mon Sep 17 00:00:00 2001
From: Ridong Chen <chenridong@xiaomi.com>
Date: Fri, 24 Jul 2026 11:34:33 +0800
Subject: [PATCH] mm: vmscan: propagate real error code from per-node proactive
 reclaim

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.

Link: https://lore.kernel.org/20260724033435.2573323-3-ridong.chen@linux.dev
Link: https://lore.kernel.org/all/20250717235604.2atyx2aobwowpge3@offworld/T/#m3514718be82a31b05726a49da9b61fbfc69a589e [1]
Fixes: b980077899ea ("mm: introduce per-node proactive reclaim interface")
Signed-off-by: Ridong Chen <chenridong@xiaomi.com>
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>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kairui Song <kasong@tencent.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zhongkun He <hezhongkun.hzk@bytedance.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index af0c42daa77d..b93bca48359a 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -8026,7 +8026,7 @@ 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);