static void __put_single_page(struct page *page)
{
__page_cache_release(page);
- free_hot_cold_page(page, 0);
+ free_hot_cold_page(page, false);
}
static void __put_compound_page(struct page *page)
(*dtor)(page);
}
-static void put_compound_page(struct page *page)
+/**
+ * Two special cases here: we could avoid taking compound_lock_irqsave
+ * and could skip the tail refcounting(in _mapcount).
+ *
+ * 1. Hugetlbfs page:
+ *
+ * PageHeadHuge will remain true until the compound page
+ * is released and enters the buddy allocator, and it could
+ * not be split by __split_huge_page_refcount().
+ *
+ * So if we see PageHeadHuge set, and we have the tail page pin,
+ * then we could safely put head page.
+ *
+ * 2. Slab THP page:
+ *
+ * PG_slab is cleared before the slab frees the head page, and
+ * tail pin cannot be the last reference left on the head page,
+ * because the slab code is free to reuse the compound page
+ * after a kfree/kmem_cache_free without having to check if
+ * there's any tail pin left. In turn all tail pinsmust be always
+ * released while the head is still pinned by the slab code
+ * and so we know PG_slab will be still set too.
+ *
+ * So if we see PageSlab set, and we have the tail page pin,
+ * then we could safely put head page.
+ */
+static __always_inline
+void put_unrefcounted_compound_page(struct page *page_head, struct page *page)
{
- struct page *page_head;
-
- if (likely(!PageTail(page))) {
- if (put_page_testzero(page)) {
- /*
- * By the time all refcounts have been released
- * split_huge_page cannot run anymore from under us.
- */
- if (PageHead(page))
- __put_compound_page(page);
- else
- __put_single_page(page);
- }
- return;
- }
-
- /* __split_huge_page_refcount can run under us */
- page_head = compound_head(page);
-
/*
- * THP can not break up slab pages so avoid taking
- * compound_lock() and skip the tail page refcounting (in
- * _mapcount) too. Slab performs non-atomic bit ops on
- * page->flags for better performance. In particular
- * slab_unlock() in slub used to be a hot path. It is still
- * hot on arches that do not support
- * this_cpu_cmpxchg_double().
- *
- * If "page" is part of a slab or hugetlbfs page it cannot be
- * splitted and the head page cannot change from under us. And
- * if "page" is part of a THP page under splitting, if the
- * head page pointed by the THP tail isn't a THP head anymore,
- * we'll find PageTail clear after smp_rmb() and we'll treat
- * it as a single page.
+ * If @page is a THP tail, we must read the tail page
+ * flags after the head page flags. The
+ * __split_huge_page_refcount side enforces write memory barriers
+ * between clearing PageTail and before the head page
+ * can be freed and reallocated.
*/
- if (!__compound_tail_refcounted(page_head)) {
+ smp_rmb();
+ if (likely(PageTail(page))) {
/*
- * If "page" is a THP tail, we must read the tail page
- * flags after the head page flags. The
- * split_huge_page side enforces write memory barriers
- * between clearing PageTail and before the head page
- * can be freed and reallocated.
+ * __split_huge_page_refcount cannot race
+ * here, see the comment above this function.
*/
- smp_rmb();
- if (likely(PageTail(page))) {
- /*
- * __split_huge_page_refcount cannot race
- * here.
- */
- VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
- VM_BUG_ON_PAGE(page_mapcount(page) != 0, page);
- if (put_page_testzero(page_head)) {
- /*
- * If this is the tail of a slab
- * compound page, the tail pin must
- * not be the last reference held on
- * the page, because the PG_slab
- * cannot be cleared before all tail
- * pins (which skips the _mapcount
- * tail refcounting) have been
- * released. For hugetlbfs the tail
- * pin may be the last reference on
- * the page instead, because
- * PageHeadHuge will not go away until
- * the compound page enters the buddy
- * allocator.
- */
- VM_BUG_ON_PAGE(PageSlab(page_head), page_head);
- __put_compound_page(page_head);
- }
- return;
- } else
+ VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
+ VM_BUG_ON_PAGE(page_mapcount(page) != 0, page);
+ if (put_page_testzero(page_head)) {
/*
- * __split_huge_page_refcount run before us,
- * "page" was a THP tail. The split page_head
- * has been freed and reallocated as slab or
- * hugetlbfs page of smaller order (only
- * possible if reallocated as slab on x86).
+ * If this is the tail of a slab THP page,
+ * the tail pin must not be the last reference
+ * held on the page, because the PG_slab cannot
+ * be cleared before all tail pins (which skips
+ * the _mapcount tail refcounting) have been
+ * released.
+ *
+ * If this is the tail of a hugetlbfs page,
+ * the tail pin may be the last reference on
+ * the page instead, because PageHeadHuge will
+ * not go away until the compound page enters
+ * the buddy allocator.
*/
- goto out_put_single;
- }
+ VM_BUG_ON_PAGE(PageSlab(page_head), page_head);
+ __put_compound_page(page_head);
+ }
+ } else
+ /*
+ * __split_huge_page_refcount run before us,
+ * @page was a THP tail. The split @page_head
+ * has been freed and reallocated as slab or
+ * hugetlbfs page of smaller order (only
+ * possible if reallocated as slab on x86).
+ */
+ if (put_page_testzero(page))
+ __put_single_page(page);
+}
+static __always_inline
+void put_refcounted_compound_page(struct page *page_head, struct page *page)
+{
if (likely(page != page_head && get_page_unless_zero(page_head))) {
unsigned long flags;
/*
- * page_head wasn't a dangling pointer but it may not
+ * @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.
compound_unlock_irqrestore(page_head, flags);
if (put_page_testzero(page_head)) {
/*
- * The head page may have been freed
+ * The @page_head may have been freed
* and reallocated as a compound page
* of smaller order and then freed
* again. All we know is that it
__put_single_page(page_head);
}
} else {
- /* page_head is a dangling pointer */
+ /* @page_head is a dangling pointer */
VM_BUG_ON_PAGE(PageTail(page), page);
goto out_put_single;
}
}
+static void put_compound_page(struct page *page)
+{
+ struct page *page_head;
+
+ /*
+ * We see the PageCompound set and PageTail not set, so @page maybe:
+ * 1. hugetlbfs head page, or
+ * 2. THP head page.
+ */
+ if (likely(!PageTail(page))) {
+ if (put_page_testzero(page)) {
+ /*
+ * By the time all refcounts have been released
+ * split_huge_page cannot run anymore from under us.
+ */
+ if (PageHead(page))
+ __put_compound_page(page);
+ else
+ __put_single_page(page);
+ }
+ return;
+ }
+
+ /*
+ * We see the PageCompound set and PageTail set, so @page maybe:
+ * 1. a tail hugetlbfs page, or
+ * 2. a tail THP page, or
+ * 3. a split THP page.
+ *
+ * Case 3 is possible, as we may race with
+ * __split_huge_page_refcount tearing down a THP page.
+ */
+ page_head = compound_head_by_tail(page);
+ if (!__compound_tail_refcounted(page_head))
+ put_unrefcounted_compound_page(page_head, page);
+ else
+ put_refcounted_compound_page(page_head, page);
+}
+
void put_page(struct page *page)
{
if (unlikely(PageCompound(page)))
page_cache_get(page);
local_irq_save(flags);
- pvec = &__get_cpu_var(lru_rotate_pvecs);
+ pvec = this_cpu_ptr(&lru_rotate_pvecs);
if (!pagevec_add(pvec, page))
pagevec_move_tail(pvec);
local_irq_restore(flags);
EXPORT_SYMBOL(mark_page_accessed);
/*
- * Queue the page for addition to the LRU via pagevec. The decision on whether
- * to add the page to the [in]active [file|anon] list is deferred until the
- * pagevec is drained. This gives a chance for the caller of __lru_cache_add()
- * have the page added to the active list using mark_page_accessed().
+ * Used to mark_page_accessed(page) that is not visible yet and when it is
+ * still safe to use non-atomic ops
*/
-void __lru_cache_add(struct page *page)
+void init_page_accessed(struct page *page)
+{
+ if (!PageReferenced(page))
+ __SetPageReferenced(page);
+}
+EXPORT_SYMBOL(init_page_accessed);
+
+static void __lru_cache_add(struct page *page)
{
struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
pagevec_add(pvec, page);
put_cpu_var(lru_add_pvec);
}
-EXPORT_SYMBOL(__lru_cache_add);
+
+/**
+ * lru_cache_add: add a page to the page lists
+ * @page: the page to add
+ */
+void lru_cache_add_anon(struct page *page)
+{
+ if (PageActive(page))
+ ClearPageActive(page);
+ __lru_cache_add(page);
+}
+
+void lru_cache_add_file(struct page *page)
+{
+ if (PageActive(page))
+ ClearPageActive(page);
+ __lru_cache_add(page);
+}
+EXPORT_SYMBOL(lru_cache_add_file);
/**
* lru_cache_add - add a page to a page list
* @page: the page to be added to the LRU.
+ *
+ * Queue the page for addition to the LRU via pagevec. The decision on whether
+ * to add the page to the [in]active [file|anon] list is deferred until the
+ * pagevec is drained. This gives a chance for the caller of lru_cache_add()
+ * have the page added to the active list using mark_page_accessed().
*/
void lru_cache_add(struct page *page)
{
* grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
* will free it.
*/
-void release_pages(struct page **pages, int nr, int cold)
+void release_pages(struct page **pages, int nr, bool cold)
{
int i;
LIST_HEAD(pages_to_free);
}
/* Clear Active bit in case of parallel mark_page_accessed */
- ClearPageActive(page);
+ __ClearPageActive(page);
list_add(&page->lru, &pages_to_free);
}
git.openpandora.org / pandora-kernel.git / blobdiff