From: David Hildenbrand (Arm) <david@kernel.org>
Date: Fri, 20 Mar 2026 22:13:38 +0000 (+0100)
Subject: mm/sparse: remove !CONFIG_SPARSEMEM_VMEMMAP leftovers for CONFIG_MEMORY_HOTPLUG
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=119c31caa59e84931cca713a00a58be61bfa7baa;p=thirdparty%2Fkernel%2Flinux.git

mm/sparse: remove !CONFIG_SPARSEMEM_VMEMMAP leftovers for CONFIG_MEMORY_HOTPLUG

CONFIG_MEMORY_HOTPLUG now depends on CONFIG_SPARSEMEM_VMEMMAP.  So let's
remove the !CONFIG_SPARSEMEM_VMEMMAP leftovers that are dead code.

Adjust the comment above fill_subsection_map() accordingly.

Link: https://lkml.kernel.org/r/20260320-sparsemem_cleanups-v2-6-096addc8800d@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/sparse.c b/mm/sparse.c
index 93252112860e3..875f718a4c797 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -657,7 +657,6 @@ void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
 	}
 }
 
-#ifdef CONFIG_SPARSEMEM_VMEMMAP
 static struct page * __meminit populate_section_memmap(unsigned long pfn,
 		unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
 		struct dev_pagemap *pgmap)
@@ -729,73 +728,11 @@ static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
 
 	return rc;
 }
-#else
-static struct page * __meminit populate_section_memmap(unsigned long pfn,
-		unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
-		struct dev_pagemap *pgmap)
-{
-	return kvmalloc_node(array_size(sizeof(struct page),
-					PAGES_PER_SECTION), GFP_KERNEL, nid);
-}
-
-static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
-		struct vmem_altmap *altmap)
-{
-	kvfree(pfn_to_page(pfn));
-}
-
-static void free_map_bootmem(struct page *memmap)
-{
-	unsigned long maps_section_nr, removing_section_nr, i;
-	unsigned long type, nr_pages;
-	struct page *page = virt_to_page(memmap);
-
-	nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
-		>> PAGE_SHIFT;
-
-	for (i = 0; i < nr_pages; i++, page++) {
-		type = bootmem_type(page);
-
-		BUG_ON(type == NODE_INFO);
-
-		maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
-		removing_section_nr = bootmem_info(page);
-
-		/*
-		 * When this function is called, the removing section is
-		 * logical offlined state. This means all pages are isolated
-		 * from page allocator. If removing section's memmap is placed
-		 * on the same section, it must not be freed.
-		 * If it is freed, page allocator may allocate it which will
-		 * be removed physically soon.
-		 */
-		if (maps_section_nr != removing_section_nr)
-			put_page_bootmem(page);
-	}
-}
-
-static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
-{
-	return 0;
-}
-
-static bool is_subsection_map_empty(struct mem_section *ms)
-{
-	return true;
-}
-
-static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
-{
-	return 0;
-}
-#endif /* CONFIG_SPARSEMEM_VMEMMAP */
 
 /*
- * To deactivate a memory region, there are 3 cases to handle across
- * two configurations (SPARSEMEM_VMEMMAP={y,n}):
+ * To deactivate a memory region, there are 3 cases to handle:
  *
- * 1. deactivation of a partial hot-added section (only possible in
- *    the SPARSEMEM_VMEMMAP=y case).
+ * 1. deactivation of a partial hot-added section:
  *      a) section was present at memory init.
  *      b) section was hot-added post memory init.
  * 2. deactivation of a complete hot-added section.
@@ -803,8 +740,6 @@ static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
  *
  * For 1, when subsection_map does not empty we will not be freeing the
  * usage map, but still need to free the vmemmap range.
- *
- * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified
  */
 static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
 		struct vmem_altmap *altmap)