Messages in this thread Patch in this message | | | From | Peter Xu <> | Subject | [PATCH RFC 07/10] mm/hugetlb: Make hugetlb_follow_page_mask() RCU-safe | Date | Sun, 30 Oct 2022 17:29:26 -0400 |
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RCU makes sure the pte_t* won't go away from under us. Please refer to the comment above huge_pte_offset() for more information.
Signed-off-by: Peter Xu <peterx@redhat.com> --- mm/hugetlb.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 9869c12e6460..85214095fb85 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6229,10 +6229,12 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, if (WARN_ON_ONCE(flags & FOLL_PIN)) return NULL; + /* For huge_pte_offset() */ + rcu_read_lock(); retry: pte = huge_pte_offset(mm, haddr, huge_page_size(h)); if (!pte) - return NULL; + goto out_rcu; ptl = huge_pte_lock(h, mm, pte); entry = huge_ptep_get(pte); @@ -6266,6 +6268,8 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, } out: spin_unlock(ptl); +out_rcu: + rcu_read_unlock(); return page; } -- 2.37.3
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