Merge tag 'gfs2-4.8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2...

[cascardo/linux.git] / arch / arm64 / mm / pageattr.c

diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index ca6d268..8def55e 100644 (file)
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -139,4 +139,43 @@ void __kernel_map_pages(struct page *page, int numpages, int enable)
                                        __pgprot(0),
                                        __pgprot(PTE_VALID));
 }
-#endif
+#ifdef CONFIG_HIBERNATION
+/*
+ * When built with CONFIG_DEBUG_PAGEALLOC and CONFIG_HIBERNATION, this function
+ * is used to determine if a linear map page has been marked as not-valid by
+ * CONFIG_DEBUG_PAGEALLOC. Walk the page table and check the PTE_VALID bit.
+ * This is based on kern_addr_valid(), which almost does what we need.
+ *
+ * Because this is only called on the kernel linear map,  p?d_sect() implies
+ * p?d_present(). When debug_pagealloc is enabled, sections mappings are
+ * disabled.
+ */
+bool kernel_page_present(struct page *page)
+{
+       pgd_t *pgd;
+       pud_t *pud;
+       pmd_t *pmd;
+       pte_t *pte;
+       unsigned long addr = (unsigned long)page_address(page);
+
+       pgd = pgd_offset_k(addr);
+       if (pgd_none(*pgd))
+               return false;
+
+       pud = pud_offset(pgd, addr);
+       if (pud_none(*pud))
+               return false;
+       if (pud_sect(*pud))
+               return true;
+
+       pmd = pmd_offset(pud, addr);
+       if (pmd_none(*pmd))
+               return false;
+       if (pmd_sect(*pmd))
+               return true;
+
+       pte = pte_offset_kernel(pmd, addr);
+       return pte_valid(*pte);
+}
+#endif /* CONFIG_HIBERNATION */
+#endif /* CONFIG_DEBUG_PAGEALLOC */