From ef009b25f4f8a77d2b32067d424d5ac757dcdc5b Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Tue, 10 Jan 2012 15:07:21 -0800 Subject: [PATCH] hugetlb: clarify hugetlb_instantiation_mutex usage Let's make it clear that we cannot race with other fault handlers due to hugetlb (global) mutex. Also make it clear that we want to keep pte_same checks anayway to have a transition from the global mutex easier. Signed-off-by: Michal Hocko Cc: Hillf Danton Cc: Andrea Arcangeli Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 2c551b2..49e693b 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2349,6 +2349,9 @@ static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma, /* * Hugetlb_cow() should be called with page lock of the original hugepage held. + * Called with hugetlb_instantiation_mutex held and pte_page locked so we + * cannot race with other handlers or page migration. + * Keep the pte_same checks anyway to make transition from the mutex easier. */ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pte_t *ptep, pte_t pte, -- 2.7.4