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@xxxxxxxxxx> --- fs/userfaultfd.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 07c81ab3fd4d..4e813e68e4f8 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -243,6 +243,9 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, mmap_assert_locked(mm); + /* For huge_pte_offset() */ + rcu_read_lock(); + ptep = huge_pte_offset(mm, address, vma_mmu_pagesize(vma)); if (!ptep) @@ -261,6 +264,7 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, if (!huge_pte_write(pte) && (reason & VM_UFFD_WP)) ret = true; out: + rcu_read_unlock(); return ret; } #else -- 2.37.3
