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-rw-r--r--mm/hugetlb.c32
1 files changed, 30 insertions, 2 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ee6655e47213..9b79806be17b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6985,10 +6985,38 @@ struct page * __weak
follow_huge_pud(struct mm_struct *mm, unsigned long address,
pud_t *pud, int flags)
{
- if (flags & (FOLL_GET | FOLL_PIN))
+ struct page *page = NULL;
+ spinlock_t *ptl;
+ pte_t pte;
+
+ if (WARN_ON_ONCE(flags & FOLL_PIN))
return NULL;
- return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
+retry:
+ ptl = huge_pte_lock(hstate_sizelog(PUD_SHIFT), mm, (pte_t *)pud);
+ if (!pud_huge(*pud))
+ goto out;
+ pte = huge_ptep_get((pte_t *)pud);
+ if (pte_present(pte)) {
+ page = pud_page(*pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
+ if (WARN_ON_ONCE(!try_grab_page(page, flags))) {
+ page = NULL;
+ goto out;
+ }
+ } else {
+ if (is_hugetlb_entry_migration(pte)) {
+ spin_unlock(ptl);
+ __migration_entry_wait(mm, (pte_t *)pud, ptl);
+ goto retry;
+ }
+ /*
+ * hwpoisoned entry is treated as no_page_table in
+ * follow_page_mask().
+ */
+ }
+out:
+ spin_unlock(ptl);
+ return page;
}
struct page * __weak