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authorAndrea Arcangeli2011-11-02 13:37:15 -0700
committerLinus Torvalds2011-11-02 16:06:57 -0700
commit3526741f0964c88bc2ce511e1078359052bf225b (patch)
treed651d4826523ffeebc92e7863a918de955c15840 /arch
parent8596468487e2062cae2aad56e973784e03959245 (diff)
powerpc: gup_hugepte() support THP based tail recounting
Up to this point the code assumed old refcounting for hugepages (pre-thp). This updates the code directly to the thp mapcount tail page refcounting. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/mm/hugetlbpage.c24
1 files changed, 23 insertions, 1 deletions
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 78b14abded65..a618ef01bfad 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -385,12 +385,23 @@ follow_huge_pmd(struct mm_struct *mm, unsigned long address,
return NULL;
}
+static inline void get_huge_page_tail(struct page *page)
+{
+ /*
+ * __split_huge_page_refcount() cannot run
+ * from under us.
+ */
+ VM_BUG_ON(page_mapcount(page) < 0);
+ VM_BUG_ON(atomic_read(&page->_count) != 0);
+ atomic_inc(&page->_mapcount);
+}
+
static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
unsigned long mask;
unsigned long pte_end;
- struct page *head, *page;
+ struct page *head, *page, *tail;
pte_t pte;
int refs;
@@ -413,6 +424,7 @@ static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long add
head = pte_page(pte);
page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
+ tail = page;
do {
VM_BUG_ON(compound_head(page) != head);
pages[*nr] = page;
@@ -431,6 +443,16 @@ static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long add
*nr -= refs;
while (refs--)
put_page(head);
+ } else {
+ /*
+ * Any tail page need their mapcount reference taken
+ * before we return.
+ */
+ while (refs--) {
+ if (PageTail(tail))
+ get_huge_page_tail(tail);
+ tail++;
+ }
}
return 1;