[PATCH 5.17 074/114] x86/mm: Fix marking of unused sub-pmd ranges

[Greg Kroah-Hartman]

From: Adrian-Ken Rueegsegger <ken@xxxxxxxxxxx>

commit 280abe14b6e0a38de9cc86fe6a019523aadd8f70 upstream.

The unused part precedes the new range spanned by the start, end parameters
of vmemmap_use_new_sub_pmd(). This means it actually goes from
ALIGN_DOWN(start, PMD_SIZE) up to start.

Use the correct address when applying the mark using memset.

Fixes: 8d400913c231 ("x86/vmemmap: handle unpopulated sub-pmd ranges")
Signed-off-by: Adrian-Ken Rueegsegger <ken@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20220509090637.24152-2-ken@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/x86/mm/init_64.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -902,6 +902,8 @@ static void __meminit vmemmap_use_sub_pm
 
 static void __meminit vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end)
 {
+	const unsigned long page = ALIGN_DOWN(start, PMD_SIZE);
+
 	vmemmap_flush_unused_pmd();
 
 	/*
@@ -914,8 +916,7 @@ static void __meminit vmemmap_use_new_su
 	 * Mark with PAGE_UNUSED the unused parts of the new memmap range
 	 */
 	if (!IS_ALIGNED(start, PMD_SIZE))
-		memset((void *)start, PAGE_UNUSED,
-			start - ALIGN_DOWN(start, PMD_SIZE));
+		memset((void *)page, PAGE_UNUSED, start - page);
 
 	/*
 	 * We want to avoid memset(PAGE_UNUSED) when populating the vmemmap of