[PATCH v6 10/10] mm,memory_hotplug: Drop status_change_nid parameter from memory_notify

Oscar Salvador
2025-06-09T09:22:48Z

The 'status_change_nid' field was used to track changes in the memory
state of a numa node, but that funcionality has been decoupled from
memory_notify and moved to node_notify.
Current consumers of memory_notify are only interested in which node the
memory we are adding belongs to, but we can derive the nid from the pfn
because we call move_pfn_range_to_zone(), which sets the node in the page
via __init_single_page(), before calling in any memory notifier.

Drop the 'status_change_nid' parameter from 'memory_notify' struct and update documentation
accordingly.

Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
Documentation/core-api/memory-hotplug.rst | 7 -------
include/linux/memory.h | 1 -
mm/memory_hotplug.c | 2 --
mm/page_ext.c | 16 +++-------------
4 files changed, 3 insertions(+), 23 deletions(-)

diff --git a/Documentation/core-api/memory-hotplug.rst b/Documentation/core-api/memory-hotplug.rst
index b19c3be7437d..74897713c4f8 100644
--- a/Documentation/core-api/memory-hotplug.rst
+++ b/Documentation/core-api/memory-hotplug.rst
@@ -59,17 +59,10 @@ The third argument (arg) passes a pointer of struct memory_notify::
struct memory_notify {
unsigned long start_pfn;
unsigned long nr_pages;
- int status_change_nid;
}

- start_pfn is start_pfn of online/offline memory.
- nr_pages is # of pages of online/offline memory.
-- status_change_nid is set node id when N_MEMORY of nodemask is (will be)
- set/clear. It means a new(memoryless) node gets new memory by online and a
- node loses all memory. If this is -1, then nodemask status is not changed.
-
- If status_changed_nid* >= 0, callback should create/discard structures for the
- node if necessary.

The callback routine shall return one of the values
NOTIFY_DONE, NOTIFY_OK, NOTIFY_BAD, NOTIFY_STOP
diff --git a/include/linux/memory.h b/include/linux/memory.h
index a9ccd6579422..de8b898ada3f 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -109,7 +109,6 @@ struct memory_notify {
unsigned long altmap_nr_pages;
unsigned long start_pfn;
unsigned long nr_pages;
- int status_change_nid;
};

struct notifier_block;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 0550f3061fc4..07d7bdb65761 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1186,7 +1186,6 @@ int online_pages(unsigned long pfn, unsigned long nr_pages,

mem_arg.start_pfn = pfn;
mem_arg.nr_pages = nr_pages;
- mem_arg.status_change_nid = node_arg.nid;
cancel_mem_notifier_on_err = true;
ret = memory_notify(MEM_GOING_ONLINE, &mem_arg);
ret = notifier_to_errno(ret);
@@ -1987,7 +1986,6 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages,

mem_arg.start_pfn = start_pfn;
mem_arg.nr_pages = nr_pages;
- mem_arg.status_change_nid = node_arg.nid;
cancel_mem_notifier_on_err = true;
ret = memory_notify(MEM_GOING_OFFLINE, &mem_arg);
ret = notifier_to_errno(ret);
diff --git a/mm/page_ext.c b/mm/page_ext.c
index c351fdfe9e9a..f08353802fa6 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -369,25 +369,15 @@ static void __invalidate_page_ext(unsigned long pfn)
}

static int __meminit online_page_ext(unsigned long start_pfn,
- unsigned long nr_pages,
- int nid)
+ unsigned long nr_pages)
{
unsigned long start, end, pfn;
int fail = 0;
+ int nid = pfn_to_nid(start_pfn);

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)
@@ -436,7 +426,7 @@ static int __meminit page_ext_callback(struct notifier_block *self,
switch (action) {
case MEM_GOING_ONLINE:
ret = online_page_ext(mn->start_pfn,
- mn->nr_pages, mn->status_change_nid);
+ mn->nr_pages);
break;
case MEM_OFFLINE:
offline_page_ext(mn->start_pfn,
--
2.49.0