From: Yosry Ahmed <yosry.ahmed@linux.dev>
Date: Fri, 16 Jan 2026 20:52:47 +0000 (+0000)
Subject: mm: restore per-memcg proactive reclaim with !CONFIG_NUMA
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=16aca2c98a6fdf071e5a1a765a295995d7c7e346;p=thirdparty%2Fkernel%2Flinux.git

mm: restore per-memcg proactive reclaim with !CONFIG_NUMA

Commit 2b7226af730c ("mm/memcg: make memory.reclaim interface generic")
moved proactive reclaim logic from memory.reclaim handler to a generic
user_proactive_reclaim() helper to be used for per-node proactive reclaim.

However, user_proactive_reclaim() was only defined under CONFIG_NUMA, with
a stub always returning 0 otherwise.  This broke memory.reclaim on
!CONFIG_NUMA configs, causing it to report success without actually
attempting reclaim.

Move the definition of user_proactive_reclaim() outside CONFIG_NUMA, and
instead define a stub for __node_reclaim() in the !CONFIG_NUMA case.
__node_reclaim() is only called from user_proactive_reclaim() when a write
is made to sys/devices/system/node/nodeX/reclaim, which is only defined
with CONFIG_NUMA.

Link: https://lkml.kernel.org/r/20260116205247.928004-1-yosry.ahmed@linux.dev
Fixes: 2b7226af730c ("mm/memcg: make memory.reclaim interface generic")
Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/internal.h b/mm/internal.h
index e430da900430..f35dbcf99a86 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -538,16 +538,8 @@ extern unsigned long highest_memmap_pfn;
 bool folio_isolate_lru(struct folio *folio);
 void folio_putback_lru(struct folio *folio);
 extern void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason);
-#ifdef CONFIG_NUMA
 int user_proactive_reclaim(char *buf,
 			   struct mem_cgroup *memcg, pg_data_t *pgdat);
-#else
-static inline int user_proactive_reclaim(char *buf,
-			   struct mem_cgroup *memcg, pg_data_t *pgdat)
-{
-	return 0;
-}
-#endif
 
 /*
  * in mm/rmap.c:
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 670fe9fae5ba..614ccf39fe3f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -7707,6 +7707,17 @@ int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)
 	return ret;
 }
 
+#else
+
+static unsigned long __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask,
+				    unsigned long nr_pages,
+				    struct scan_control *sc)
+{
+	return 0;
+}
+
+#endif
+
 enum {
 	MEMORY_RECLAIM_SWAPPINESS = 0,
 	MEMORY_RECLAIM_SWAPPINESS_MAX,
@@ -7814,8 +7825,6 @@ int user_proactive_reclaim(char *buf,
 	return 0;
 }
 
-#endif
-
 /**
  * check_move_unevictable_folios - Move evictable folios to appropriate zone
  * lru list