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x86/mm: Fix freeing of PMD-sized vmemmap pages

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Commit bf9e4e30f3 ("x86/mm: use pagetable_free()"), switched from
freeing non-boot page tables through __free_pages() to
pagetable_free().

However, the function is also called to free vmemmap pages.

Given that vmemmap pages are not page tables, already the page_ptdesc(page)
is wrong. But worse, pagetable_free() calls:

	__free_pages(page, compound_order(page));

Since vmemmap pages are not compound pages (see vmemmap_alloc_block())
-- except for HVO, which doesn't apply here -- only first page of a
PMD-sized vmemmap page is freed, leaking the other ones.

Fix it by properly decoupling pagetable and vmemmap freeing.
free_pagetable() no longer has to mess with SECTION_INFO, as only the
vmemmap is marked like that in register_page_bootmem_memmap().

The indentation in remove_pmd_table() is messed up. Fix that while
touching it.

Bootmem info handling will soon be fixed up. For now, handle it
similar to free_pagetable(), just avoiding the ifdef.

[ dhansen: changelog munging. More imperative voice ]

Fixes: bf9e4e30f3 ("x86/mm: use pagetable_free()")
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: Lance Yang <lance.yang@linux.dev>
Link: https://lore.kernel.org/20260429-vmemmap-v2-1-8dfcacffd877@kernel.org
Link: https://patch.msgid.link/20260429-vmemmap-v2-1-8dfcacffd877@kernel.org
Cc: stable@vger.kernel.org
This commit is contained in:
David Hildenbrand (Arm) 2026-04-29 12:49:14 +02:00 committed by Dave Hansen
parent 952ac097ce
commit 39406c05f8
1 changed files with 26 additions and 14 deletions
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40
arch/x86/mm/init_64.c
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@ -1014,7 +1014,7 @@ static void __meminit free_pagetable(struct page *page, int order)
#ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE
enum bootmem_type type = bootmem_type(page);
if (type == SECTION_INFO || type == MIX_SECTION_INFO) {
if (type == MIX_SECTION_INFO) {
while (nr_pages--)
put_page_bootmem(page++);
} else {
@ -1028,13 +1028,24 @@ static void __meminit free_pagetable(struct page *page, int order)
}
}
static void __meminit free_hugepage_table(struct page *page,
static void __meminit free_vmemmap_pages(struct page *page, unsigned int order,
struct vmem_altmap *altmap)
{
if (altmap)
vmem_altmap_free(altmap, PMD_SIZE / PAGE_SIZE);
else
free_pagetable(page, get_order(PMD_SIZE));
unsigned long nr_pages = 1u << order;
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, nr_pages);
}
} else {
__free_pages(page, order);
}
}
static void __meminit free_pte_table(pte_t *pte_start, pmd_t *pmd)
@ -1118,7 +1129,8 @@ remove_pte_table(pte_t *pte_start, unsigned long addr, unsigned long end,
return;
if (!direct)
free_pagetable(pte_page(*pte), 0);
/* We never populate base pages from the altmap. */
free_vmemmap_pages(pte_page(*pte), 0, NULL);
spin_lock(&init_mm.page_table_lock);
pte_clear(&init_mm, addr, pte);
@ -1153,19 +1165,19 @@ remove_pmd_table(pmd_t *pmd_start, unsigned long addr, unsigned long end,
if (IS_ALIGNED(addr, PMD_SIZE) &&
IS_ALIGNED(next, PMD_SIZE)) {
if (!direct)
free_hugepage_table(pmd_page(*pmd),
altmap);
free_vmemmap_pages(pmd_page(*pmd),
PMD_ORDER, altmap);
spin_lock(&init_mm.page_table_lock);
pmd_clear(pmd);
spin_unlock(&init_mm.page_table_lock);
pages++;
} else if (vmemmap_pmd_is_unused(addr, next)) {
free_hugepage_table(pmd_page(*pmd),
altmap);
spin_lock(&init_mm.page_table_lock);
pmd_clear(pmd);
spin_unlock(&init_mm.page_table_lock);
free_vmemmap_pages(pmd_page(*pmd), PMD_ORDER,
altmap);
spin_lock(&init_mm.page_table_lock);
pmd_clear(pmd);
spin_unlock(&init_mm.page_table_lock);
}
continue;
}