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authorAndrea Arcangeli <aarcange@redhat.com>2011-01-14 00:46:32 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-14 02:32:39 +0100
commit9180706344487700b40da9eca5dedd3d11cb33b4 (patch)
treeeb0347efe7e40adc78a271752c7382aa67875d6a /arch/x86
parentthp: compound_lock (diff)
downloadlinux-9180706344487700b40da9eca5dedd3d11cb33b4.tar.xz
linux-9180706344487700b40da9eca5dedd3d11cb33b4.zip
thp: alter compound get_page/put_page
Alter compound get_page/put_page to keep references on subpages too, in order to allow __split_huge_page_refcount to split an hugepage even while subpages have been pinned by one of the get_user_pages() variants. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/mm/gup.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 738e6593799d..06f56fcf9a77 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -105,6 +105,16 @@ static inline void get_head_page_multiple(struct page *page, int nr)
atomic_add(nr, &page->_count);
}
+static inline void get_huge_page_tail(struct page *page)
+{
+ /*
+ * __split_huge_page_refcount() cannot run
+ * from under us.
+ */
+ VM_BUG_ON(atomic_read(&page->_count) < 0);
+ atomic_inc(&page->_count);
+}
+
static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
@@ -128,6 +138,8 @@ static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
do {
VM_BUG_ON(compound_head(page) != head);
pages[*nr] = page;
+ if (PageTail(page))
+ get_huge_page_tail(page);
(*nr)++;
page++;
refs++;