[PATCH RFC v2 07/12] mm/hugetlb: Use hugetlb walker lock in hugetlb_follow_page_mask()

Peter Xu
2022-11-18T01:12:48Z

Hugetlb walker lock makes sure the pte_t* won't go away from under us.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
mm/hugetlb.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 5ef883184885..fc49e3ca8acd 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6222,9 +6222,10 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
if (WARN_ON_ONCE(flags & FOLL_PIN))
return NULL;

+ hugetlb_walker_lock();
pte = huge_pte_offset(mm, haddr, huge_page_size(h));
if (!pte)
- return NULL;
+ goto out_unlock;

ptl = huge_pte_lock(h, mm, pte);
entry = huge_ptep_get(pte);
@@ -6247,6 +6248,8 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
}
out:
spin_unlock(ptl);
+out_unlock:
+ hugetlb_walker_unlock();
return page;
}

--
2.37.3