+#ifdef CONFIG_DEBUG_PAGEALLOC
+
+static int __change_page_attr(struct page *page, pgprot_t prot)
+{
+ pte_t *kpte;
+ pmd_t *kpmd;
+ unsigned long address;
+
+ BUG_ON(PageHighMem(page));
+ address = (unsigned long)page_address(page);
+
+ if (v_mapped_by_bats(address) || v_mapped_by_tlbcam(address))
+ return 0;
+ if (!get_pteptr(&init_mm, address, &kpte, &kpmd))
+ return -EINVAL;
+ set_pte_at(&init_mm, address, kpte, mk_pte(page, prot));
+ wmb();
+ flush_HPTE(0, address, pmd_val(*kpmd));
+ pte_unmap(kpte);
+
+ return 0;
+}
+
+/*
+ * Change the page attributes of an page in the linear mapping.
+ *
+ * THIS CONFLICTS WITH BAT MAPPINGS, DEBUG USE ONLY
+ */
+static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
+{
+ int i, err = 0;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ for (i = 0; i < numpages; i++, page++) {
+ err = __change_page_attr(page, prot);
+ if (err)
+ break;
+ }
+ local_irq_restore(flags);
+ return err;
+}
+
+
+void kernel_map_pages(struct page *page, int numpages, int enable)
+{
+ if (PageHighMem(page))
+ return;
+
+ change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
+}
+#endif /* CONFIG_DEBUG_PAGEALLOC */