goto out_unlock;
page = pmd_page(pmd);
+ BUG_ON(is_huge_zero_page(page));
page_nid = page_to_nid(page);
count_vm_numa_event(NUMA_HINT_FAULTS);
if (page_nid == this_nid)
} else {
struct page *page = pmd_page(*pmd);
- /* only check non-shared pages */
+ /*
+ * Only check non-shared pages. Do not trap faults
+ * against the zero page. The read-only data is likely
+ * to be read-cached on the local CPU cache and it is
+ * less useful to know about local vs remote hits on
+ * the zero page.
+ */
if (page_mapcount(page) == 1 &&
+ !is_huge_zero_page(page) &&
!pmd_numa(*pmd)) {
entry = pmdp_get_and_clear(mm, addr, pmd);
entry = pmd_mknuma(entry);
pte_unmap_unlock(ptep, ptl);
return 0;
}
+ BUG_ON(is_zero_pfn(page_to_pfn(page)));
page_nid = page_to_nid(page);
target_nid = numa_migrate_prep(page, vma, addr, page_nid);