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x86/mm: stop marking vmemmap as SECTION_INFO

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We added the whole bootmem registration machinery in commit 0475327876
("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.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-5-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand (Arm)
2026-07-16 16:51:04 +02:00
committed by Andrew Morton
parent f4436442e5
commit 7bfc04d6bd
1 changed files with 4 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

30
arch/x86/mm/init_64.c
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@@ -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);
}
}
}