And the follow up documentation patch: --- >From 51bef05e4cbf97a749e6c0245114eceb21d05d61 Mon Sep 17 00:00:00 2001 From: Michal Hocko <mhocko@xxxxxxx> Date: Mon, 21 Nov 2011 15:39:45 +0100 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 <mhocko@xxxxxxx> --- mm/hugetlb.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index f76c7ea..611cdc8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2348,6 +2348,9 @@ 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, -- 1.7.7.1 -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>