From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758846AbXLTJC3 (ORCPT ); Thu, 20 Dec 2007 04:02:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754657AbXLTJCK (ORCPT ); Thu, 20 Dec 2007 04:02:10 -0500 Received: from e3.ny.us.ibm.com ([32.97.182.143]:57014 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754011AbXLTJCI (ORCPT ); Thu, 20 Dec 2007 04:02:08 -0500 From: Balbir Singh To: Hugh Dickins Cc: Balbir Singh , LKML , Andrew Morton , KAMEZAWA Hiroyuki Date: Thu, 20 Dec 2007 14:31:52 +0530 Message-Id: <20071220090152.19793.46738.sendpatchset@balbir-laptop> Subject: [PATCH] Memory controller use rcu_read_lock() in mem_cgroup_cache_charge() Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hugh Dickins noticed that we were using rcu_dereference() without rcu_read_lock() in the cache charging routine. The patch below fixes this problem Signed-off-by: Balbir Singh --- mm/memcontrol.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff -puN mm/memcontrol.c~memory-controller-use-rcu-lead-lock mm/memcontrol.c --- linux-2.6.24-rc5/mm/memcontrol.c~memory-controller-use-rcu-lead-lock 2007-12-19 11:52:44.000000000 +0530 +++ linux-2.6.24-rc5-balbir/mm/memcontrol.c 2007-12-20 14:01:45.000000000 +0530 @@ -717,16 +717,20 @@ int mem_cgroup_charge(struct page *page, int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask) { + int ret = 0; struct mem_cgroup *mem; if (!mm) mm = &init_mm; + rcu_read_lock(); mem = rcu_dereference(mm->mem_cgroup); + css_get(&mem->css); + rcu_read_unlock(); if (mem->control_type == MEM_CGROUP_TYPE_ALL) - return mem_cgroup_charge_common(page, mm, gfp_mask, + ret = mem_cgroup_charge_common(page, mm, gfp_mask, MEM_CGROUP_CHARGE_TYPE_CACHE); - else - return 0; + css_put(&mem->css); + return ret; } /* _ -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL