1 files changed, 45 insertions, 5 deletions

diff --git a/kernel/resource.c b/kernel/resource.c
index f9bb5481501a..b9fa2a4ce089 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1388,6 +1388,47 @@ void __release_region(struct resource *parent, resource_size_t start,
 EXPORT_SYMBOL(__release_region);
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
+static void append_child_to_parent(struct resource *new_parent, struct resource *new_child)
+{
+	struct resource *child;
+
+	child = new_parent->child;
+	if (child) {
+		while (child->sibling)
+			child = child->sibling;
+		child->sibling = new_child;
+	} else {
+		new_parent->child = new_child;
+	}
+	new_child->parent = new_parent;
+	new_child->sibling = NULL;
+}
+
+/*
+ * Reparent all child resources that no longer belong to "low" after a split to
+ * "high". Note that "high" does not have any children, because "low" is the
+ * original resource and "high" is a new resource. Treat "low" as the original
+ * resource being split and defer its range adjustment to __adjust_resource().
+ */
+static void reparent_children_after_split(struct resource *low,
+					  struct resource *high,
+					  resource_size_t split_addr)
+{
+	struct resource *child, *next, **p;
+
+	p = &low->child;
+	while ((child = *p)) {
+		next = child->sibling;
+		if (child->start > split_addr) {
+			/* unlink child */
+			*p = next;
+			append_child_to_parent(high, child);
+		} else {
+			p = &child->sibling;
+		}
+	}
+}
+
 /**
  * release_mem_region_adjustable - release a previously reserved memory region
  * @start: resource start address
@@ -1397,15 +1438,13 @@ EXPORT_SYMBOL(__release_region);
  * is released from a currently busy memory resource.  The requested region
  * must either match exactly or fit into a single busy resource entry.  In
  * the latter case, the remaining resource is adjusted accordingly.
- * Existing children of the busy memory resource must be immutable in the
- * request.
  *
  * Note:
  * - Additional release conditions, such as overlapping region, can be
  *   supported after they are confirmed as valid cases.
- * - When a busy memory resource gets split into two entries, the code
- *   assumes that all children remain in the lower address entry for
- *   simplicity.  Enhance this logic when necessary.
+ * - When a busy memory resource gets split into two entries, its children are
+ *   reassigned to the correct parent based on their range. If a child memory
+ *   resource overlaps with more than one parent, enhance the logic as needed.
  */
 void release_mem_region_adjustable(resource_size_t start, resource_size_t size)
 {
@@ -1482,6 +1521,7 @@ retry:
 			new_res->parent = res->parent;
 			new_res->sibling = res->sibling;
 			new_res->child = NULL;
+			reparent_children_after_split(res, new_res, end);
 
 			if (WARN_ON_ONCE(__adjust_resource(res, res->start,
 							   start - res->start)))