Commit ef009b25 authored Jan 10, 2012 by Michal Hocko Committed by Linus Torvalds Jan 10, 2012

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@suse.cz>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent a734bcc8

mm/hugetlb.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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,