[PATCH v3 1/1] mm: numa_memblks: introduce numa_add_reserved_memblk

[PATCH v3 1/1] mm: numa_memblks: introduce numa_add_reserved_memblk

[Yuquan Wang]

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 support of future hotplug / CXL provisioning.

Introduce and use numa_add_reserved_memblk() to add the empty CFMWS
ranges directly.

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

Changes in v3 (Thanks to Dan & huacai):
- The previous version failed to build on loongarch, now this issue is resolved.

 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 0a725e46d017..751774f0b4e5 100644
--- a/drivers/acpi/numa/srat.c
+++ b/drivers/acpi/numa/srat.c
@@ -453,7 +453,7 @@ 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

Re: [PATCH v3 1/1] mm: numa_memblks: introduce numa_add_reserved_memblk

[Alison Schofield]

On Thu, May 08, 2025 at 10:27:19AM +0800, Yuquan Wang wrote:
> 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 support of future hotplug / CXL provisioning.
> 
> Introduce and use numa_add_reserved_memblk() to add the empty CFMWS
> ranges directly.
> 
> Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>

Reviewed-by: Alison Schofield <alison.schofield@intel.com>

Re: [PATCH v3 1/1] mm: numa_memblks: introduce numa_add_reserved_memblk

[Jonathan Cameron]

On Wed, 7 May 2025 21:09:07 -0700
Alison Schofield <alison.schofield@intel.com> wrote:

> On Thu, May 08, 2025 at 10:27:19AM +0800, Yuquan Wang wrote:
> > 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 support of future hotplug / CXL provisioning.
> > 
> > Introduce and use numa_add_reserved_memblk() to add the empty CFMWS
> > ranges directly.
> > 
> > Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>  
> 
> Reviewed-by: Alison Schofield <alison.schofield@intel.com>
> 
> 
> 

Yuquan - I'm guessing this is a misunderstanding of process.
The patch submitter should pick up tags on previous versions.
If any are not picked up in the tag block there should be a clear
explanation of why!

Jonathan

Re: [PATCH v3 1/1] mm: numa_memblks: introduce numa_add_reserved_memblk

[Andrew Morton]

On Thu,  8 May 2025 10:27:19 +0800 Yuquan Wang <wangyuquan1236@phytium.com.cn> wrote:

> 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 support of future hotplug / CXL provisioning.
> 
> Introduce and use numa_add_reserved_memblk() to add the empty CFMWS
> ranges directly.
> 
> ...
>
>  drivers/acpi/numa/srat.c     |  2 +-
>  include/linux/numa_memblks.h |  1 +
>  mm/numa_memblks.c            | 22 ++++++++++++++++++++++

I'm not sure which tree this best belongs to so I'll add it to mm-git. 
If it later pops up in another tree, I'll drop it again.

Re: [PATCH v3 1/1] mm: numa_memblks: introduce numa_add_reserved_memblk

[Guenter Roeck]

Hi,

On Thu, May 08, 2025 at 10:27:19AM +0800, Yuquan Wang wrote:
> 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 support of future hotplug / CXL provisioning.
> 
> Introduce and use numa_add_reserved_memblk() to add the empty CFMWS
> ranges directly.
> 
> Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>

Just on case this has not been reported yet:

Building loongarch:defconfig ... failed
--------------
Error log:
drivers/acpi/numa/srat.c: In function 'acpi_parse_cfmws':
drivers/acpi/numa/srat.c:467:13: error: implicit declaration of function 'numa_add_reserved_memblk' 

Guenter

Re: [PATCH v3 1/1] mm: numa_memblks: introduce numa_add_reserved_memblk

[Xi Ruoyao]

On Tue, 2025-06-03 at 06:06 -0700, Guenter Roeck wrote:
> Hi,
> 
> On Thu, May 08, 2025 at 10:27:19AM +0800, Yuquan Wang wrote:
> > 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 support of future hotplug / CXL
> > provisioning.
> > 
> > Introduce and use numa_add_reserved_memblk() to add the empty CFMWS
> > ranges directly.
> > 
> > Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>
> 
> Just on case this has not been reported yet:
> 
> Building loongarch:defconfig ... failed
> --------------
> Error log:
> drivers/acpi/numa/srat.c: In function 'acpi_parse_cfmws':
> drivers/acpi/numa/srat.c:467:13: error: implicit declaration of
> function 'numa_add_reserved_memblk' 

The fix is queued at
https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson.git/commit/?h=loongarch-next&id=a24f2fb70cb62180486ad4d74f809ff35ddd1cf9


-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University