The patch titled
shared page table for hugetlb page - v2 (comments)
has been added to the -mm tree. Its filename is
shared-page-table-for-hugetlb-page-v2-comments.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: shared page table for hugetlb page - v2 (comments)
From: "Chen, Kenneth W" <kenneth.w.chen@xxxxxxxxx>
Signed-off-by: Ken Chen <kenneth.w.chen@xxxxxxxxx>
Cc: Dave McCracken <dmccr@xxxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Cc: Adam Litke <agl@xxxxxxxxxx>
Cc: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
Cc: William Lee Irwin III <wli@xxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/i386/mm/hugetlbpage.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff -puN arch/i386/mm/hugetlbpage.c~shared-page-table-for-hugetlb-page-v2-comments arch/i386/mm/hugetlbpage.c
--- a/arch/i386/mm/hugetlbpage.c~shared-page-table-for-hugetlb-page-v2-comments
+++ a/arch/i386/mm/hugetlbpage.c
@@ -58,6 +58,11 @@ static void pmd_share(struct vm_area_str
spin_lock(&svma->vm_mm->page_table_lock);
spte = huge_pte_offset(svma->vm_mm, addr);
+ /*
+ * if a valid hugetlb pte is found, take a reference count
+ * on the pte page. We can then safely populate it into
+ * pud at a later point.
+ */
if (spte)
get_page(virt_to_page(spte));
spin_unlock(&svma->vm_mm->page_table_lock);
@@ -77,6 +82,16 @@ static void pmd_share(struct vm_area_str
spin_unlock(&vma->vm_mm->page_table_lock);
}
+/*
+ * unmap huge page backed by shared pte.
+ *
+ * Hugetlb pte page is ref counted at the time of mapping. If pte is shared
+ * indicated by page_count > 1, unmap is achieved by clearing pud and
+ * decrementing the ref count. If count == 1, the pte page is not shared.
+ *
+ * returns: 1 successfully unmapped a shared pte page
+ * 0 the underlying pte page is not shared, or it is the last user
+ */
int huge_pte_put(struct vm_area_struct *vma, unsigned long *addr, pte_t *ptep)
{
pgd_t *pgd = pgd_offset(vma->vm_mm, *addr);
_
Patches currently in -mm which might be from kenneth.w.chen@xxxxxxxxx are
shared-page-table-for-hugetlb-page-v2.patch
shared-page-table-for-hugetlb-page-v2-tidy.patch
shared-page-table-for-hugetlb-page-v2-comments.patch
clean-up-unused-kiocb-variables.patch
-
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