[PATCH 05/10] x86/mm: stop marking vmemmap as SECTION_INFO

["David Hildenbrand (Arm)" <david@kernel.org>]

We added the whole bootmem registration machinery in commit 04753278769f
("memory hotplug: register section/node id to free").

The main use case was to remember to which memory section memmap pages
belonged, so the memmap could be handled accordingly when freeing
memory.

However, all that machinery is not required anymore: a memory section
can only get offlined if *all* pages can get offlined; and it can only
get unplugged once offline. If some of these pages are unmovable memmap
pages: bad luck, doesn't work. Offlining will fail.

Further, a lot of this machinery was required for pre-vmemmap support.
Now we only support the vmemmap with memory hotplug.

So the whole machinery is useless today. Let's start by removing the
last pieces by first stopping to mark vmemmap pages as SECTION_INFO.
In free_vmemmap_pages(), we can now always just free the reserved pages
directly.

Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
---
 arch/x86/mm/init_64.c | 30 ++++--------------------------
 1 file changed, 4 insertions(+), 26 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 320e742b0bb3f..82bb0384b8ab0 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1024,19 +1024,12 @@ static void __meminit free_vmemmap_pages(struct page *page, unsigned int order,
 {
 	unsigned long nr_pages = 1u << order;
 
-	if (altmap) {
+	if (altmap)
 		vmem_altmap_free(altmap, nr_pages);
-	} else if (PageReserved(page)) {
-		if (IS_ENABLED(CONFIG_HAVE_BOOTMEM_INFO_NODE) &&
-		    bootmem_type(page) == SECTION_INFO) {
-			while (nr_pages--)
-				put_page_bootmem(page++);
-		} else {
-			free_reserved_pages(page, order);
-		}
-	} else {
+	else if (PageReserved(page))
+		free_reserved_pages(page, order);
+	else
 		__free_pages(page, order);
-	}
 }
 
 static void __meminit free_pte_table(pte_t *pte_start, pmd_t *pmd)
@@ -1593,12 +1586,8 @@ void register_page_bootmem_memmap(unsigned long section_nr,
 	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
-	unsigned int nr_pmd_pages;
-	struct page *page;
 
 	for (; addr < end; addr = next) {
-		pte_t *pte = NULL;
-
 		pgd = pgd_offset_k(addr);
 		if (pgd_none(*pgd)) {
 			next = (addr + PAGE_SIZE) & PAGE_MASK;
@@ -1630,19 +1619,8 @@ void register_page_bootmem_memmap(unsigned long section_nr,
 			next = (addr + PAGE_SIZE) & PAGE_MASK;
 			get_page_bootmem(section_nr, pmd_page(*pmd),
 					 MIX_SECTION_INFO);
-
-			pte = pte_offset_kernel(pmd, addr);
-			if (pte_none(*pte))
-				continue;
-			get_page_bootmem(section_nr, pte_page(*pte),
-					 SECTION_INFO);
 		} else {
 			next = pmd_addr_end(addr, end);
-			nr_pmd_pages = (next - addr) >> PAGE_SHIFT;
-			page = pmd_page(*pmd);
-			while (nr_pmd_pages--)
-				get_page_bootmem(section_nr, page++,
-						 SECTION_INFO);
 		}
 	}
 }

-- 
2.43.0