[PATCH] remove set_page_count() outside mm/
set_page_count usage outside mm/ is limited to setting the refcount to 1.
Remove set_page_count from outside mm/, and replace those users with
init_page_count() and set_page_refcounted().
This allows more debug checking, and tighter control on how code is allowed
to play around with page->_count.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 39d49ec..20117a4 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -18,6 +18,7 @@
#include <asm/pgtable.h>
#include <linux/hugetlb.h>
+#include "internal.h"
const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
static unsigned long nr_huge_pages, free_huge_pages;
@@ -106,7 +107,7 @@
return NULL;
}
spin_unlock(&hugetlb_lock);
- set_page_count(page, 1);
+ set_page_refcounted(page);
for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
clear_user_highpage(&page[i], addr);
return page;
@@ -152,7 +153,7 @@
1 << PG_private | 1<< PG_writeback);
}
page[1].lru.next = NULL;
- set_page_count(page, 1);
+ set_page_refcounted(page);
__free_pages(page, HUGETLB_PAGE_ORDER);
}
diff --git a/mm/internal.h b/mm/internal.h
index 7bb3397..d20e3cc 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -13,8 +13,19 @@
#include <linux/mm.h>
-static inline void set_page_refs(struct page *page, int order)
+static inline void set_page_count(struct page *page, int v)
{
+ atomic_set(&page->_count, v);
+}
+
+/*
+ * Turn a non-refcounted page (->_count == 0) into refcounted with
+ * a count of one.
+ */
+static inline void set_page_refcounted(struct page *page)
+{
+ BUG_ON(PageCompound(page) && page_private(page) != (unsigned long)page);
+ BUG_ON(atomic_read(&page->_count));
set_page_count(page, 1);
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e197818..7f65b5a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -442,7 +442,7 @@
if (order == 0) {
__ClearPageReserved(page);
set_page_count(page, 0);
- set_page_refs(page, 0);
+ set_page_refcounted(page);
__free_page(page);
} else {
int loop;
@@ -457,7 +457,7 @@
set_page_count(p, 0);
}
- set_page_refs(page, order);
+ set_page_refcounted(page);
__free_pages(page, order);
}
}
@@ -525,7 +525,7 @@
1 << PG_referenced | 1 << PG_arch_1 |
1 << PG_checked | 1 << PG_mappedtodisk);
set_page_private(page, 0);
- set_page_refs(page, order);
+ set_page_refcounted(page);
kernel_map_pages(page, 1 << order, 1);
return 0;
}
@@ -755,10 +755,8 @@
BUG_ON(PageCompound(page));
BUG_ON(!page_count(page));
- for (i = 1; i < (1 << order); i++) {
- BUG_ON(page_count(page + i));
- set_page_count(page + i, 1);
- }
+ for (i = 1; i < (1 << order); i++)
+ set_page_refcounted(page + i);
}
/*
@@ -1771,7 +1769,7 @@
continue;
page = pfn_to_page(pfn);
set_page_links(page, zone, nid, pfn);
- set_page_count(page, 1);
+ init_page_count(page);
reset_page_mapcount(page);
SetPageReserved(page);
INIT_LIST_HEAD(&page->lru);