summaryrefslogtreecommitdiffstats
path: root/mm/huge_memory.c
diff options
context:
space:
mode:
Diffstat (limited to 'mm/huge_memory.c')
-rw-r--r--mm/huge_memory.c24
1 files changed, 16 insertions, 8 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 33a5dc49281..51f069303ab 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1243,6 +1243,10 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
return ERR_PTR(-EFAULT);
+ /* Full NUMA hinting faults to serialise migration in fault paths */
+ if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
+ goto out;
+
page = pmd_page(*pmd);
VM_BUG_ON(!PageHead(page));
if (flags & FOLL_TOUCH) {
@@ -1323,23 +1327,27 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
/* If the page was locked, there are no parallel migrations */
if (page_locked)
goto clear_pmdnuma;
+ }
- /*
- * Otherwise wait for potential migrations and retry. We do
- * relock and check_same as the page may no longer be mapped.
- * As the fault is being retried, do not account for it.
- */
+ /*
+ * If there are potential migrations, wait for completion and retry. We
+ * do not relock and check_same as the page may no longer be mapped.
+ * Furtermore, even if the page is currently misplaced, there is no
+ * guarantee it is still misplaced after the migration completes.
+ */
+ if (!page_locked) {
spin_unlock(ptl);
wait_on_page_locked(page);
page_nid = -1;
goto out;
}
- /* Page is misplaced, serialise migrations and parallel THP splits */
+ /*
+ * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
+ * to serialises splits
+ */
get_page(page);
spin_unlock(ptl);
- if (!page_locked)
- lock_page(page);
anon_vma = page_lock_anon_vma_read(page);
/* Confirm the PMD did not change while page_table_lock was released */