remove_pte_table() is prepared to handle the case where either the
start or the end of the range is not PAGE aligned.
This cannot actually happen:

__populate_section_memmap enforces the range to be PMD aligned,
so as long as the size of the struct page remains multiple of 8,
the vmemmap range will be aligned to PAGE_SIZE.

Drop the dead code and place a VM_BUG_ON in vmemmap_{populate,free}
to catch nasty cases.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
Suggested-by: David Hildenbrand <redacted>
---
  arch/x86/mm/init_64.c | 48 ++++++++++++-------------------------------
  1 file changed, 13 insertions(+), 35 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index b5a3fa4033d3..b0e1d215c83e 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c

@@ -962,7 +962,6 @@ remove_pte_table(pte_t *pte_start, unsigned long addr, unsigned long end,
  {
  	unsigned long next, pages = 0;
  	pte_t *pte;
-	void *page_addr;
  	phys_addr_t phys_addr;
  
  	pte = pte_start + pte_index(addr);

@@ -983,42 +982,15 @@ remove_pte_table(pte_t *pte_start, unsigned long addr, unsigned long end,
  		if (phys_addr < (phys_addr_t)0x40000000)
  			return;
  
-		if (PAGE_ALIGNED(addr) && PAGE_ALIGNED(next)) {
-			/*
-			 * Do not free direct mapping pages since they were
-			 * freed when offlining, or simplely not in use.
-			 */
-			if (!direct)
-				free_pagetable(pte_page(*pte), 0);
-
-			spin_lock(&init_mm.page_table_lock);
-			pte_clear(&init_mm, addr, pte);
-			spin_unlock(&init_mm.page_table_lock);
+		if (!direct)
+			free_pagetable(pte_page(*pte), 0);
  
-			/* For non-direct mapping, pages means nothing. */
-			pages++;
-		} else {
-			/*
-			 * If we are here, we are freeing vmemmap pages since
-			 * direct mapped memory ranges to be freed are aligned.
-			 *
-			 * If we are not removing the whole page, it means
-			 * other page structs in this page are being used and
-			 * we canot remove them. So fill the unused page_structs
-			 * with 0xFD, and remove the page when it is wholly
-			 * filled with 0xFD.
-			 */
-			memset((void *)addr, PAGE_INUSE, next - addr);
-
-			page_addr = page_address(pte_page(*pte));
-			if (!memchr_inv(page_addr, PAGE_INUSE, PAGE_SIZE)) {
-				free_pagetable(pte_page(*pte), 0);
+		spin_lock(&init_mm.page_table_lock);
+		pte_clear(&init_mm, addr, pte);
+		spin_unlock(&init_mm.page_table_lock);
  
-				spin_lock(&init_mm.page_table_lock);
-				pte_clear(&init_mm, addr, pte);
-				spin_unlock(&init_mm.page_table_lock);
-			}
-		}
+		/* For non-direct mapping, pages means nothing. */
+		pages++;
  	}
  
  	/* Call free_pte_table() in remove_pmd_table(). */

@@ -1197,6 +1169,9 @@ remove_pagetable(unsigned long start, unsigned long end, bool direct,
  void __ref vmemmap_free(unsigned long start, unsigned long end,
  		struct vmem_altmap *altmap)
  {
+	VM_BUG_ON(!IS_ALIGNED(start, PAGE_SIZE));
+	VM_BUG_ON(!IS_ALIGNED(end, PAGE_SIZE));
+
  	remove_pagetable(start, end, false, altmap);
  }
  

@@ -1556,6 +1531,9 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
  {
  	int err;
  
+	VM_BUG_ON(!IS_ALIGNED(start, PAGE_SIZE));
+	VM_BUG_ON(!IS_ALIGNED(end, PAGE_SIZE));
+
  	if (end - start < PAGES_PER_SECTION * sizeof(struct page))
  		err = vmemmap_populate_basepages(start, end, node, NULL);
  	else if (boot_cpu_has(X86_FEATURE_PSE))