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Diffstat (limited to 'mm/swap.c')
-rw-r--r--mm/swap.c77
1 files changed, 52 insertions, 25 deletions
diff --git a/mm/swap.c b/mm/swap.c
index 62b78a6e224f..c899502d3e36 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -31,6 +31,7 @@
#include <linux/memcontrol.h>
#include <linux/gfp.h>
#include <linux/uio.h>
+#include <linux/hugetlb.h>
#include "internal.h"
@@ -81,6 +82,19 @@ static void __put_compound_page(struct page *page)
static void put_compound_page(struct page *page)
{
+ /*
+ * hugetlbfs pages cannot be split from under us. If this is a
+ * hugetlbfs page, check refcount on head page and release the page if
+ * the refcount becomes zero.
+ */
+ if (PageHuge(page)) {
+ page = compound_head(page);
+ if (put_page_testzero(page))
+ __put_compound_page(page);
+
+ return;
+ }
+
if (unlikely(PageTail(page))) {
/* __split_huge_page_refcount can run under us */
struct page *page_head = compound_trans_head(page);
@@ -184,38 +198,51 @@ bool __get_page_tail(struct page *page)
* proper PT lock that already serializes against
* split_huge_page().
*/
- unsigned long flags;
bool got = false;
- struct page *page_head = compound_trans_head(page);
+ struct page *page_head;
- if (likely(page != page_head && get_page_unless_zero(page_head))) {
+ /*
+ * If this is a hugetlbfs page it cannot be split under us. Simply
+ * increment refcount for the head page.
+ */
+ if (PageHuge(page)) {
+ page_head = compound_head(page);
+ atomic_inc(&page_head->_count);
+ got = true;
+ } else {
+ unsigned long flags;
+
+ page_head = compound_trans_head(page);
+ if (likely(page != page_head &&
+ get_page_unless_zero(page_head))) {
+
+ /* Ref to put_compound_page() comment. */
+ if (PageSlab(page_head)) {
+ if (likely(PageTail(page))) {
+ __get_page_tail_foll(page, false);
+ return true;
+ } else {
+ put_page(page_head);
+ return false;
+ }
+ }
- /* Ref to put_compound_page() comment. */
- if (PageSlab(page_head)) {
+ /*
+ * page_head wasn't a dangling pointer but it
+ * may not be a head page anymore by the time
+ * we obtain the lock. That is ok as long as it
+ * can't be freed from under us.
+ */
+ flags = compound_lock_irqsave(page_head);
+ /* here __split_huge_page_refcount won't run anymore */
if (likely(PageTail(page))) {
__get_page_tail_foll(page, false);
- return true;
- } else {
- put_page(page_head);
- return false;
+ got = true;
}
+ compound_unlock_irqrestore(page_head, flags);
+ if (unlikely(!got))
+ put_page(page_head);
}
-
- /*
- * page_head wasn't a dangling pointer but it
- * may not be a head page anymore by the time
- * we obtain the lock. That is ok as long as it
- * can't be freed from under us.
- */
- flags = compound_lock_irqsave(page_head);
- /* here __split_huge_page_refcount won't run anymore */
- if (likely(PageTail(page))) {
- __get_page_tail_foll(page, false);
- got = true;
- }
- compound_unlock_irqrestore(page_head, flags);
- if (unlikely(!got))
- put_page(page_head);
}
return got;
}