Merge tag 'x86-urgent-2022-05-15' of git://git.kernel.org/pub/scm/lin…

…ux/kernel/git/tip/tip

Pull x86 fix from Thomas Gleixner:
 "A single fix for the handling of unpopulated sub-pmd spaces.

  The copy & pasta from the corresponding s390 code screwed up the
  address calculation for marking the sub-pmd ranges via memset by
  omitting the ALIGN_DOWN() to calculate the proper start address.

  It's a mystery why this code is not generic and shared because there
  is nothing architecture specific in there, but that's too intrusive
  for a backportable fix"

* tag 'x86-urgent-2022-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: Fix marking of unused sub-pmd ranges

arch/x86/mm/init_64.c

@@ -902,6 +902,8 @@ static void __meminit vmemmap_use_sub_pmd(unsigned long start, unsigned long end
 
 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_sub_pmd(unsigned long start, unsigned long
 	 * 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