From 9c67a20704e763f9cb8cd262c3e45de7bd2816bc Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Fri, 16 Dec 2022 10:52:29 -0500 Subject: mm/hugetlb: introduce hugetlb_walk() huge_pte_offset() is the main walker function for hugetlb pgtables. The name is not really representing what it does, though. Instead of renaming it, introduce a wrapper function called hugetlb_walk() which will use huge_pte_offset() inside. Assert on the locks when walking the pgtable. Note, the vma lock assertion will be a no-op for private mappings. Document the last special case in the page_vma_mapped_walk() path where we don't need any more lock to call hugetlb_walk(). Taking vma lock there is not needed because either: (1) potential callers of hugetlb pvmw holds i_mmap_rwsem already (from one rmap_walk()), or (2) the caller will not walk a hugetlb vma at all so the hugetlb code path not reachable (e.g. in ksm or uprobe paths). It's slightly implicit for future page_vma_mapped_walk() callers on that lock requirement. But anyway, when one day this rule breaks, one will get a straightforward warning in hugetlb_walk() with lockdep, then there'll be a way out. [akpm@linux-foundation.org: coding-style cleanups] Link: https://lkml.kernel.org/r/20221216155229.2043750-1-peterx@redhat.com Signed-off-by: Peter Xu Reviewed-by: Mike Kravetz Reviewed-by: John Hubbard Reviewed-by: David Hildenbrand Cc: Andrea Arcangeli Cc: James Houghton Cc: Jann Horn Cc: Miaohe Lin Cc: Muchun Song Cc: Nadav Amit Cc: Rik van Riel Signed-off-by: Andrew Morton --- fs/userfaultfd.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'fs/userfaultfd.c') diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 3b1797e0448a5d..15a5bf765d4327 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -252,14 +252,12 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, unsigned long flags, unsigned long reason) { - struct mm_struct *mm = ctx->mm; pte_t *ptep, pte; bool ret = true; - mmap_assert_locked(mm); - - ptep = huge_pte_offset(mm, address, vma_mmu_pagesize(vma)); + mmap_assert_locked(ctx->mm); + ptep = hugetlb_walk(vma, address, vma_mmu_pagesize(vma)); if (!ptep) goto out; -- cgit 1.2.3-korg