linux-kernel - [PATCH 07/10] zsmalloc: add obj_handle_is

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]

Date:	Thu, 11 Sep 2014 16:53:58 -0400
From:	Dan Streetman <ddstreet@...e.org>
To:	Minchan Kim <minchan@...nel.org>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Nitin Gupta <ngupta@...are.org>,
	Seth Jennings <sjennings@...iantweb.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Streetman <ddstreet@...e.org>
Subject: [PATCH 07/10] zsmalloc: add obj_handle_is_free()

Add function obj_handle_is_free() which scans through the entire
singly-linked list of free objects inside the provided zspage to
determine if the provided object handle is free or not.  This is
required by zspage reclaiming, which needs to evict each object
that is currently in use by the zs_pool owner, but has no other
way to determine if an object is in use.

Signed-off-by: Dan Streetman <ddstreet@...e.org>
Cc: Minchan Kim <minchan@...nel.org>
---
 mm/zsmalloc.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 3dc7dae..ab72390 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -605,6 +605,33 @@ static unsigned long obj_idx_to_offset(struct page *page,
 	return off + obj_idx * class_size;
 }
 
+static bool obj_handle_is_free(struct page *first_page,
+			struct size_class *class, unsigned long handle)
+{
+	unsigned long obj, idx, offset;
+	struct page *page;
+	struct link_free *link;
+
+	BUG_ON(!is_first_page(first_page));
+
+	obj = (unsigned long)first_page->freelist;
+
+	while (obj) {
+		if (obj == handle)
+			return true;
+
+		obj_handle_to_location(obj, &page, &idx);
+		offset = obj_idx_to_offset(page, idx, class->size);
+
+		link = (struct link_free *)kmap_atomic(page) +
+					offset / sizeof(*link);
+		obj = (unsigned long)link->next;
+		kunmap_atomic(link);
+	}
+
+	return false;
+}
+
 static void obj_free(unsigned long obj, struct page *page, unsigned long offset)
 {
 	struct page *first_page = get_first_page(page);
-- 
1.8.3.1

--
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/