linux-kernel - [PATCH 1/4] pull out the page pre-release and sanity check logic for reuse

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1220467452-15794-2-git-send-email-apw@shadowen.org>
Date:	Wed,  3 Sep 2008 19:44:09 +0100
From:	Andy Whitcroft <apw@...dowen.org>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Mel Gorman <mel@....ul.ie>, Andy Whitcroft <apw@...dowen.org>
Subject: [PATCH 1/4] pull out the page pre-release and sanity check logic for reuse

When we are about to release a page we perform a number of actions
on that page.  We clear down any anonymous mappings, confirm that
the page is safe to release, check for freeing locks, before mapping
the page should that be required.  Pull this processing out into a
helper function for reuse in a later patch.

Note that we do not convert the similar cleardown in free_hot_cold_page()
as the optimiser is unable to squash the loops during the inline.

Signed-off-by: Andy Whitcroft <apw@...dowen.org>
---
 mm/page_alloc.c |   43 ++++++++++++++++++++++++++++++-------------
 1 files changed, 30 insertions(+), 13 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f52fcf1..b2a2c2b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -489,6 +489,35 @@ static inline int free_pages_check(struct page *page)
 }
 
 /*
+ * Prepare this page for release to the buddy.  Sanity check the page.
+ * Returns 1 if the page is safe to free.
+ */
+static inline int free_page_prepare(struct page *page, int order)
+{
+	int i;
+	int reserved = 0;
+
+	if (PageAnon(page))
+		page->mapping = NULL;
+
+	for (i = 0 ; i < (1 << order) ; ++i)
+		reserved += free_pages_check(page + i);
+	if (reserved)
+		return 0;
+
+	if (!PageHighMem(page)) {
+		debug_check_no_locks_freed(page_address(page),
+							PAGE_SIZE << order);
+		debug_check_no_obj_freed(page_address(page),
+					   PAGE_SIZE << order);
+	}
+	arch_free_page(page, order);
+	kernel_map_pages(page, 1 << order, 0);
+
+	return 1;
+}
+
+/*
  * Frees a list of pages. 
  * Assumes all pages on list are in same zone, and of same order.
  * count is the number of pages to free.
@@ -529,22 +558,10 @@ static void free_one_page(struct zone *zone, struct page *page, int order)
 static void __free_pages_ok(struct page *page, unsigned int order)
 {
 	unsigned long flags;
-	int i;
-	int reserved = 0;
 
-	for (i = 0 ; i < (1 << order) ; ++i)
-		reserved += free_pages_check(page + i);
-	if (reserved)
+	if (!free_page_prepare(page, order))
 		return;
 
-	if (!PageHighMem(page)) {
-		debug_check_no_locks_freed(page_address(page),PAGE_SIZE<<order);
-		debug_check_no_obj_freed(page_address(page),
-					   PAGE_SIZE << order);
-	}
-	arch_free_page(page, order);
-	kernel_map_pages(page, 1 << order, 0);
-
 	local_irq_save(flags);
 	__count_vm_events(PGFREE, 1 << order);
 	free_one_page(page_zone(page), page, order);
-- 
1.6.0.rc1.258.g80295

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/