return ERR_PTR(-EFAULT);
/* Full NUMA hinting faults to serialise migration in fault paths */
- if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
+ if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
goto out;
page = pmd_page(*pmd);
bool migrated = false;
int flags = 0;
+ /* A PROT_NONE fault should not end up here */
+ BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
+
ptl = pmd_lock(mm, pmdp);
if (unlikely(!pmd_same(pmd, *pmdp)))
goto out_unlock;
* check_same as the page may no longer be mapped.
*/
if (unlikely(pmd_trans_migrating(*pmdp))) {
+ page = pmd_page(*pmdp);
spin_unlock(ptl);
- wait_migrate_huge_page(vma->anon_vma, pmdp);
+ wait_on_page_locked(page);
goto out;
}
* Avoid grouping on DSO/COW pages in specific and RO pages
* in general, RO pages shouldn't hurt as much anyway since
* they can be in shared cache state.
+ *
+ * FIXME! This checks "pmd_dirty()" as an approximation of
+ * "is this a read-only page", since checking "pmd_write()"
+ * is even more broken. We haven't actually turned this into
+ * a writable page, so pmd_write() will always be false.
*/
- if (!pmd_write(pmd))
+ if (!pmd_dirty(pmd))
flags |= TNF_NO_GROUP;
/*
/*
* Migrate the THP to the requested node, returns with page unlocked
- * and pmd_numa cleared.
+ * and access rights restored.
*/
spin_unlock(ptl);
migrated = migrate_misplaced_transhuge_page(mm, vma,
goto out;
clear_pmdnuma:
BUG_ON(!PageLocked(page));
- pmd = pmd_mknonnuma(pmd);
+ pmd = pmd_modify(pmd, vma->vm_page_prot);
set_pmd_at(mm, haddr, pmdp, pmd);
- VM_BUG_ON(pmd_numa(*pmdp));
update_mmu_cache_pmd(vma, addr, pmdp);
unlock_page(page);
out_unlock:
if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
pmd_t entry;
ret = 1;
- if (!prot_numa) {
+
+ /*
+ * Avoid trapping faults against the zero page. The read-only
+ * data is likely to be read-cached on the local CPU and
+ * local/remote hits to the zero page are not interesting.
+ */
+ if (prot_numa && is_huge_zero_pmd(*pmd)) {
+ spin_unlock(ptl);
+ return ret;
+ }
+
+ if (!prot_numa || !pmd_protnone(*pmd)) {
entry = pmdp_get_and_clear_notify(mm, addr, pmd);
- if (pmd_numa(entry))
- entry = pmd_mknonnuma(entry);
entry = pmd_modify(entry, newprot);
ret = HPAGE_PMD_NR;
set_pmd_at(mm, addr, pmd, entry);
BUG_ON(pmd_write(entry));
- } else {
- struct page *page = pmd_page(*pmd);
-
- /*
- * 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 (!is_huge_zero_page(page) &&
- !pmd_numa(*pmd)) {
- pmdp_set_numa(mm, addr, pmd);
- ret = HPAGE_PMD_NR;
- }
}
spin_unlock(ptl);
}
pte_t *pte, entry;
BUG_ON(PageCompound(page+i));
/*
- * Note that pmd_numa is not transferred deliberately
- * to avoid any possibility that pte_numa leaks to
- * a PROT_NONE VMA by accident.
+ * Note that NUMA hinting access restrictions are not
+ * transferred to avoid any possibility of altering
+ * permissions across VMAs.
*/
entry = mk_pte(page + i, vma->vm_page_prot);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);