+ mmpage_ext-derive-the-node-from-the-pfn.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm,page_ext: derive the node from the pfn
has been added to the -mm mm-unstable branch.  Its filename is
     mmpage_ext-derive-the-node-from-the-pfn.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mmpage_ext-derive-the-node-from-the-pfn.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Oscar Salvador <osalvador@suse.de>
Subject: mm,page_ext: derive the node from the pfn
Date: Mon, 16 Jun 2025 15:51:53 +0200

page_ext is the only user of 'status_change_nid', which is set in
online/offline operations, to know to which node we are adding/removing
memory.

Prior to call any notifiers, the memmap is initialized via, which among
other things, sets the node the pages belong to, to all corresponging
pages.  This means that there is no need to keep using 'status_change_nid'
since we can derive the node from the pfn.  This will allow us to finally
drop 'status_change_nid' from the memory_notify struct.

Link: https://lkml.kernel.org/r/20250616135158.450136-11-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_ext.c |   17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

--- a/mm/page_ext.c~mmpage_ext-derive-the-node-from-the-pfn
+++ a/mm/page_ext.c
@@ -369,25 +369,15 @@ static void __invalidate_page_ext(unsign
 }
 
 static int __meminit online_page_ext(unsigned long start_pfn,
-				unsigned long nr_pages,
-				int nid)
+				unsigned long nr_pages)
 {
+	int nid = pfn_to_nid(start_pfn);
 	unsigned long start, end, pfn;
 	int fail = 0;
 
 	start = SECTION_ALIGN_DOWN(start_pfn);
 	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
 
-	if (nid == NUMA_NO_NODE) {
-		/*
-		 * In this case, "nid" already exists and contains valid memory.
-		 * "start_pfn" passed to us is a pfn which is an arg for
-		 * online__pages(), and start_pfn should exist.
-		 */
-		nid = pfn_to_nid(start_pfn);
-		VM_BUG_ON(!node_online(nid));
-	}
-
 	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION)
 		fail = init_section_page_ext(pfn, nid);
 	if (!fail)
@@ -435,8 +425,7 @@ static int __meminit page_ext_callback(s
 
 	switch (action) {
 	case MEM_GOING_ONLINE:
-		ret = online_page_ext(mn->start_pfn,
-				   mn->nr_pages, mn->status_change_nid);
+		ret = online_page_ext(mn->start_pfn, mn->nr_pages);
 		break;
 	case MEM_OFFLINE:
 		offline_page_ext(mn->start_pfn,
_

Patches currently in -mm which might be from osalvador@suse.de are

mmslub-do-not-special-case-n_normal-nodes-for-slab_nodes.patch
mmmemory_hotplug-remove-status_change_nid_normal-and-update-documentation.patch
mmmemory_hotplug-implement-numa-node-notifier.patch
mmslub-use-node-notifier-instead-of-memory-notifier.patch
mmmemory-tiers-use-node-notifier-instead-of-memory-notifier.patch
driverscxl-use-node-notifier-instead-of-memory-notifier.patch
drivershmat-use-node-notifier-instead-of-memory-notifier.patch
kernelcpuset-use-node-notifier-instead-of-memory-notifier.patch
mmmempolicy-use-node-notifier-instead-of-memory-notifier.patch
mmpage_ext-derive-the-node-from-the-pfn.patch
mmmemory_hotplug-drop-status_change_nid-parameter-from-memory_notify.patch