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From: "David Hildenbrand (Arm)" <david@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	 Oscar Salvador <osalvador@suse.de>,
	 Axel Rasmussen <axelrasmussen@google.com>,
	Yuanchu Xie <yuanchu@google.com>,  Wei Xu <weixugc@google.com>,
	Lorenzo Stoakes <ljs@kernel.org>,
	 "Liam R. Howlett" <Liam.Howlett@oracle.com>,
	 Vlastimil Babka <vbabka@kernel.org>,
	Mike Rapoport <rppt@kernel.org>,
	 Suren Baghdasaryan <surenb@google.com>,
	Michal Hocko <mhocko@suse.com>,
	 Sidhartha Kumar <sidhartha.kumar@oracle.com>,
	linux-mm@kvack.org,  linux-cxl@vger.kernel.org,
	linux-riscv@lists.infradead.org,
	 "David Hildenbrand (Arm)" <david@kernel.org>
Subject: [PATCH v2 06/15] mm/sparse: remove !CONFIG_SPARSEMEM_VMEMMAP leftovers for CONFIG_MEMORY_HOTPLUG
Date: Fri, 20 Mar 2026 23:13:38 +0100	[thread overview]
Message-ID: <20260320-sparsemem_cleanups-v2-6-096addc8800d@kernel.org> (raw)
In-Reply-To: <20260320-sparsemem_cleanups-v2-0-096addc8800d@kernel.org>

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.

Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
---
 mm/sparse.c | 69 ++-----------------------------------------------------------
 1 file changed, 2 insertions(+), 67 deletions(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index 93252112860e..875f718a4c79 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)

-- 
2.43.0



  parent reply	other threads:[~2026-03-20 22:14 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-20 22:13 [PATCH v2 00/15] mm: memory hot(un)plug and SPARSEMEM cleanups David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 01/15] mm/memory_hotplug: fix possible race in scan_movable_pages() David Hildenbrand (Arm)
2026-03-23 13:26   ` Lorenzo Stoakes (Oracle)
2026-03-23 13:40     ` David Hildenbrand (Arm)
2026-03-23 14:00       ` Lorenzo Stoakes (Oracle)
2026-03-20 22:13 ` [PATCH v2 02/15] mm/memory_hotplug: remove for_each_valid_pfn() usage David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 03/15] mm/sparse: remove WARN_ONs from (online|offline)_mem_sections() David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 04/15] mm/Kconfig: make CONFIG_MEMORY_HOTPLUG depend on CONFIG_SPARSEMEM_VMEMMAP David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 05/15] mm/memory_hotplug: simplify check_pfn_span() David Hildenbrand (Arm)
2026-03-20 22:13 ` David Hildenbrand (Arm) [this message]
2026-03-20 22:13 ` [PATCH v2 07/15] mm/bootmem_info: remove handling for !CONFIG_SPARSEMEM_VMEMMAP David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 08/15] mm/bootmem_info: avoid using sparse_decode_mem_map() David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 09/15] mm/sparse: remove sparse_decode_mem_map() David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 10/15] mm/sparse: remove CONFIG_MEMORY_HOTPLUG-specific usemap allocation handling David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 11/15] mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 12/15] mm/sparse: drop set_section_nid() from sparse_add_section() David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 13/15] mm/sparse: move sparse_init_one_section() to internal.h David Hildenbrand (Arm)
2026-03-23  8:49   ` David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 14/15] mm/sparse: move __section_mark_present() " David Hildenbrand (Arm)
2026-03-20 22:13 ` [PATCH v2 15/15] mm/sparse: move memory hotplug bits to sparse-vmemmap.c David Hildenbrand (Arm)
2026-03-27  2:58 ` [PATCH v2 00/15] mm: memory hot(un)plug and SPARSEMEM cleanups Andrew Morton

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