[merged mm-stable] mm-memory_hotplug-factor-out-node_is_memoryless.patch removed from -mm tree

[merged mm-stable] mm-memory_hotplug-factor-out-node_is_memoryless.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/memory_hotplug: factor out node_is_memoryless()
has been removed from the -mm tree.  Its filename was
     mm-memory_hotplug-factor-out-node_is_memoryless.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Gregory Price <gourry@gourry.net>
Subject: mm/memory_hotplug: factor out node_is_memoryless()
Date: Wed, 2 Sep 2026 15:55:07 -0400

A memoryless node neither spans present pages (populated or ZONE_DEVICE)
nor has an offline-but-added memory block still linked to it in sysfs.

try_offline_node() presently open-codes this memoryless check.

Pull that into a node_is_memoryless() helper and pull the existing
check_no_memblock_for_node_cb() helper ahead of the add/online path so
it's clearer what is happening here.

No functional change.

[akpm@linux-foundation.org: move node_is_memoryless() inside CONFIG_MEMORY_HOTREMOVE]
Link: https://lore.kernel.org/20260902195507.88655-1-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
---

 mm/memory_hotplug.c |   61 ++++++++++++++++++++++--------------------
 1 file changed, 32 insertions(+), 29 deletions(-)

--- a/mm/memory_hotplug.c~mm-memory_hotplug-factor-out-node_is_memoryless
+++ a/mm/memory_hotplug.c
@@ -1785,6 +1785,37 @@ bool mhp_range_allowed(u64 start, u64 si
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
+
+static int check_no_memblock_for_node_cb(struct memory_block *mem, void *arg)
+{
+	int nid = *(int *)arg;
+
+	/*
+	 * If a memory block belongs to multiple nodes, the stored nid is not
+	 * reliable. However, such blocks are always online (e.g., cannot get
+	 * offlined) and, therefore, are still spanned by the node.
+	 */
+	return mem->nid == nid ? -EEXIST : 0;
+}
+
+/* Caller must hold the memory hotplug lock for this check. */
+static bool node_is_memoryless(int nid)
+{
+	/*
+	 * A node still spanning pages (especially ZONE_DEVICE) is not
+	 * memoryless.  A node spans memory after move_pfn_range_to_zone(),
+	 * e.g. once a memory block has been onlined.
+	 */
+	if (node_spanned_pages(nid))
+		return false;
+	/*
+	 * Offline memory blocks may not be spanned by the node yet, but they
+	 * link to it in sysfs and can be onlined later, so the node is not
+	 * memoryless while any remain.
+	 */
+	return !for_each_memory_block(&nid, check_no_memblock_for_node_cb);
+}
+
 /*
  * Scan pfn range [start,end) to find movable/migratable pages (LRU and
  * hugetlb folio, movable_ops pages). Will skip over most unmovable
@@ -2214,18 +2245,6 @@ static int check_cpu_on_node(int nid)
 	return 0;
 }
 
-static int check_no_memblock_for_node_cb(struct memory_block *mem, void *arg)
-{
-	int nid = *(int *)arg;
-
-	/*
-	 * If a memory block belongs to multiple nodes, the stored nid is not
-	 * reliable. However, such blocks are always online (e.g., cannot get
-	 * offlined) and, therefore, are still spanned by the node.
-	 */
-	return mem->nid == nid ? -EEXIST : 0;
-}
-
 /**
  * try_offline_node
  * @nid: the node ID
@@ -2237,23 +2256,7 @@ static int check_no_memblock_for_node_cb
  */
 void try_offline_node(int nid)
 {
-	int rc;
-
-	/*
-	 * If the node still spans pages (especially ZONE_DEVICE), don't
-	 * offline it. A node spans memory after move_pfn_range_to_zone(),
-	 * e.g., after the memory block was onlined.
-	 */
-	if (node_spanned_pages(nid))
-		return;
-
-	/*
-	 * Especially offline memory blocks might not be spanned by the
-	 * node. They will get spanned by the node once they get onlined.
-	 * However, they link to the node in sysfs and can get onlined later.
-	 */
-	rc = for_each_memory_block(&nid, check_no_memblock_for_node_cb);
-	if (rc)
+	if (!node_is_memoryless(nid))
 		return;
 
 	if (check_cpu_on_node(nid))
_

Patches currently in -mm which might be from gourry@gourry.net are

proc-task_mmu-handle-special-pmds-in-clear_refs-and-pagemap.patch
mm-madvise-reclaim-isolated-folios-if-pte-restart-fails.patch
mm-madvise-use-folio_trylock-in-the-cold-pageout-pmd-split.patch
mm-damon-use-damon_get_monitor_folio-for-hugetlb-entries.patch