linux-kernel - [PATCH v2] mm: numa_memblks: introduce numa_add_reserved

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Message-Id: <20250328092132.2695299-1-wangyuquan1236@phytium.com.cn>
Date: Fri, 28 Mar 2025 17:21:32 +0800
From: Yuquan Wang <wangyuquan1236@...tium.com.cn>
To: Jonathan.Cameron@...wei.com,
	dan.j.williams@...el.com,
	rppt@...nel.org,
	rafael@...nel.org,
	lenb@...nel.org,
	akpm@...ux-foundation.org,
	alison.schofield@...el.com,
	rrichter@....com,
	bfaccini@...dia.com,
	haibo1.xu@...el.com,
	david@...hat.com
Cc: linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	chenbaozi@...tium.com.cn,
	Yuquan Wang <wangyuquan1236@...tium.com.cn>
Subject: [PATCH v2] mm: numa_memblks: introduce numa_add_reserved_memblk

With numa_add_reserved_memblk(), kernel could add numa_memblk into
numa_reserved_meminfo directly.

acpi_parse_cfmws() currently adds empty CFMWS ranges to numa_meminfo
with the expectation that numa_cleanup_meminfo moves them to
numa_reserved_meminfo. There is no need for that indirection when it is
known in advance that these unpopulated ranges are meant for
numa_reserved_meminfo in suppot of future hotplug / CXL provisioning.

Signed-off-by: Yuquan Wang <wangyuquan1236@...tium.com.cn>
---

Changes in v2 (Thanks to Dan):
- Use numa_add_reserved_memblk() to replace numa_add_memblk() in acpi_parse_cfmws()
- Add comments to describe the usage of numa_add_reserved_memblk()
- Provide a more explicit commit message

 drivers/acpi/numa/srat.c     |  2 +-
 include/linux/numa_memblks.h |  1 +
 mm/numa_memblks.c            | 22 ++++++++++++++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c
index 00ac0d7bb8c9..70f1a7c6b54a 100644
--- a/drivers/acpi/numa/srat.c
+++ b/drivers/acpi/numa/srat.c
@@ -458,7 +458,7 @@ static int __init acpi_parse_cfmws(union acpi_subtable_headers *header,
 		return -EINVAL;
 	}
 
-	if (numa_add_memblk(node, start, end) < 0) {
+	if (numa_add_reserved_memblk(node, start, end) < 0) {
 		/* CXL driver must handle the NUMA_NO_NODE case */
 		pr_warn("ACPI NUMA: Failed to add memblk for CFMWS node %d [mem %#llx-%#llx]\n",
 			node, start, end);
diff --git a/include/linux/numa_memblks.h b/include/linux/numa_memblks.h
index dd85613cdd86..991076cba7c5 100644
--- a/include/linux/numa_memblks.h
+++ b/include/linux/numa_memblks.h
@@ -22,6 +22,7 @@ struct numa_meminfo {
 };
 
 int __init numa_add_memblk(int nodeid, u64 start, u64 end);
+int __init numa_add_reserved_memblk(int nid, u64 start, u64 end);
 void __init numa_remove_memblk_from(int idx, struct numa_meminfo *mi);
 
 int __init numa_cleanup_meminfo(struct numa_meminfo *mi);
diff --git a/mm/numa_memblks.c b/mm/numa_memblks.c
index ff4054f4334d..541a99c4071a 100644
--- a/mm/numa_memblks.c
+++ b/mm/numa_memblks.c
@@ -200,6 +200,28 @@ int __init numa_add_memblk(int nid, u64 start, u64 end)
 	return numa_add_memblk_to(nid, start, end, &numa_meminfo);
 }
 
+/**
+ * numa_add_reserved_memblk - Add one numa_memblk to numa_reserved_meminfo
+ * @nid: NUMA node ID of the new memblk
+ * @start: Start address of the new memblk
+ * @end: End address of the new memblk
+ *
+ * Add a new memblk to the numa_reserved_meminfo.
+ *
+ * Usage Case: numa_cleanup_meminfo() reconciles all numa_memblk instances
+ * against memblock_type information and moves any that intersect reserved
+ * ranges to numa_reserved_meminfo. However, when that information is known
+ * ahead of time, we use numa_add_reserved_memblk() to add the numa_memblk
+ * to numa_reserved_meminfo directly.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int __init numa_add_reserved_memblk(int nid, u64 start, u64 end)
+{
+	return numa_add_memblk_to(nid, start, end, &numa_reserved_meminfo);
+}
+
 /**
  * numa_cleanup_meminfo - Cleanup a numa_meminfo
  * @mi: numa_meminfo to clean up
-- 
2.34.1