x86/mm: implement free pmd/pte page interfaces

Implement pud_free_pmd_page() and pmd_free_pte_page() on x86, which clear a given pud/pmd entry and free up lower level page table(s). The address range associated with the pud/pmd entry must have been purged by INVLPG. Link: http://lkml.kernel.org/r/[email protected] Fixes: e61ce6a ("mm: change ioremap to set up huge I/O mappings") Signed-off-by: Toshi Kani <[email protected]> Reported-by: Lei Li <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
josf · Mar 23, 2018 · 28ee90f · 28ee90f
1 parent b6bdb75
commit 28ee90f
Showing 1 changed file with 26 additions and 2 deletions.
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
@@ -712,7 +712,22 @@ int pmd_clear_huge(pmd_t *pmd)
  */
 int pud_free_pmd_page(pud_t *pud)
 {
-	return pud_none(*pud);
+	pmd_t *pmd;
+	int i;
+
+	if (pud_none(*pud))
+		return 1;
+
+	pmd = (pmd_t *)pud_page_vaddr(*pud);
+
+	for (i = 0; i < PTRS_PER_PMD; i++)
+		if (!pmd_free_pte_page(&pmd[i]))
+			return 0;
+
+	pud_clear(pud);
+	free_page((unsigned long)pmd);
+
+	return 1;
 }
 
 /**
@@ -724,6 +739,15 @@ int pud_free_pmd_page(pud_t *pud)
  */
 int pmd_free_pte_page(pmd_t *pmd)
 {
-	return pmd_none(*pmd);
+	pte_t *pte;
+
+	if (pmd_none(*pmd))
+		return 1;
+
+	pte = (pte_t *)pmd_page_vaddr(*pmd);
+	pmd_clear(pmd);
+	free_page((unsigned long)pte);
+
+	return 1;
 }
 #endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */