linux-kernel - [PATCH 2/3] slub: reduce failure of this_cpu_cmpxchg in put_cpu

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: <1340389359-2407-2-git-send-email-js1304@gmail.com>
Date:	Sat, 23 Jun 2012 03:22:38 +0900
From:	Joonsoo Kim <js1304@...il.com>
To:	Pekka Enberg <penberg@...nel.org>
Cc:	Christoph Lameter <cl@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Joonsoo Kim <js1304@...il.com>
Subject: [PATCH 2/3] slub: reduce failure of this_cpu_cmpxchg in put_cpu_partial() after unfreezing

In current implementation, after unfreezing, we doesn't touch oldpage,
so it remain 'NOT NULL'. When we call this_cpu_cmpxchg()
with this old oldpage, this_cpu_cmpxchg() is mostly be failed.

We can change value of oldpage to NULL after unfreezing,
because unfreeze_partial() ensure that all the cpu partial slabs is removed
from cpu partial list. In this time, we could expect that
this_cpu_cmpxchg is mostly succeed.

Signed-off-by: Joonsoo Kim <js1304@...il.com>

diff --git a/mm/slub.c b/mm/slub.c
index 92f1c0e..531d8ed 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1968,6 +1968,7 @@ int put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)
 				local_irq_save(flags);
 				unfreeze_partials(s);
 				local_irq_restore(flags);
+				oldpage = NULL;
 				pobjects = 0;
 				pages = 0;
 				stat(s, CPU_PARTIAL_DRAIN);
-- 
1.7.9.5

--
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/