thp: pmd_trans_huge migrate bugcheck
No pmd_trans_huge should ever materialize in migration ptes areas, because
we split the hugepage before migration ptes are instantiated.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/migrate.c b/mm/migrate.c
index 690d0de..1a531b7 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -113,6 +113,8 @@
goto out;
pmd = pmd_offset(pud, addr);
+ if (pmd_trans_huge(*pmd))
+ goto out;
if (!pmd_present(*pmd))
goto out;
@@ -632,6 +634,9 @@
/* page was freed from under us. So we are done. */
goto move_newpage;
}
+ if (unlikely(PageTransHuge(page)))
+ if (unlikely(split_huge_page(page)))
+ goto move_newpage;
/* prepare cgroup just returns 0 or -ENOMEM */
rc = -EAGAIN;
@@ -1063,7 +1068,7 @@
if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma))
goto set_status;
- page = follow_page(vma, pp->addr, FOLL_GET);
+ page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT);
err = PTR_ERR(page);
if (IS_ERR(page))