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authorMichal Hocko <mhocko@suse.cz>2012-01-10 15:07:21 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-10 16:30:42 -0800
commitef009b25f4f8a77d2b32067d424d5ac757dcdc5b (patch)
tree4972dac6ca66279277da1b328d9f6d32bcf08dd0 /mm/hugetlb.c
parenta734bcc812146cfba530e1adaf609fce1357982e (diff)
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>
Diffstat (limited to 'mm/hugetlb.c')
-rw-r--r--mm/hugetlb.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2c551b28ba6..49e693b7fd0 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,