From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
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@xxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
---
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -105,6 +105,10 @@ static inline int PageTransHuge(struct p
VM_BUG_ON(PageTail(page));
return PageHead(page);
}
+static inline int PageTransCompound(struct page *page)
+{
+ return PageCompound(page);
+}
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
#define HPAGE_PMD_SHIFT ({ BUG(); 0; })
#define HPAGE_PMD_MASK ({ BUG(); 0; })
@@ -122,6 +126,7 @@ static inline int split_huge_page(struct
#define wait_split_huge_page(__anon_vma, __pmd) \
do { } while (0)
#define PageTransHuge(page) 0
+#define PageTransCompound(page) 0
static inline int hugepage_madvise(unsigned long *vm_flags)
{
BUG_ON(0);
diff --git a/mm/migrate.c b/mm/migrate.c
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -100,6 +100,7 @@ static int remove_migration_pte(struct p
goto out;
pmd = pmd_offset(pud, addr);
+ VM_BUG_ON(pmd_trans_huge(*pmd));
if (!pmd_present(*pmd))
goto out;
@@ -556,6 +557,9 @@ static int unmap_and_move(new_page_t get
/* 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;
@@ -816,6 +820,10 @@ static int do_move_page_to_node_array(st
if (PageReserved(page) || PageKsm(page))
goto put_and_set;
+ if (unlikely(PageTransCompound(page)))
+ if (unlikely(split_huge_page(page)))
+ goto put_and_set;
+
pp->page = page;
err = page_to_nid(page);
--
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