From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx167.postini.com [74.125.245.167]) by kanga.kvack.org (Postfix) with SMTP id 748576B0031 for ; Tue, 6 Aug 2013 20:55:14 -0400 (EDT) Message-ID: <52019ACF.1020006@huawei.com> Date: Wed, 7 Aug 2013 08:54:39 +0800 From: Jianguo Wu MIME-Version: 1.0 Subject: Re: [PATCH] mm/mempolicy: return NULL if node is NUMA_NO_NODE in get_task_policy References: <52007660.7070907@huawei.com> <20130806140326.1d0d75874e6be221a432c3bc@linux-foundation.org> In-Reply-To: <20130806140326.1d0d75874e6be221a432c3bc@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Mel Gorman , KOSAKI Motohiro , Rik van Riel , Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hanjun Guo Hi Andrew, On 2013/8/7 5:03, Andrew Morton wrote: > On Tue, 6 Aug 2013 12:06:56 +0800 Jianguo Wu wrote: > >> If node == NUMA_NO_NODE, pol is NULL, we should return NULL instead of >> do "if (!pol->mode)" check. >> >> Signed-off-by: Jianguo Wu >> --- >> mm/mempolicy.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/mm/mempolicy.c b/mm/mempolicy.c >> index 4baf12e..e0e3398 100644 >> --- a/mm/mempolicy.c >> +++ b/mm/mempolicy.c >> @@ -129,6 +129,8 @@ static struct mempolicy *get_task_policy(struct task_struct *p) >> node = numa_node_id(); >> if (node != NUMA_NO_NODE) >> pol = &preferred_node_policy[node]; >> + else >> + return NULL; >> >> /* preferred_node_policy is not initialised early in boot */ >> if (!pol->mode) > > Well yes, it'll dereference a null pointer > > This is neater, I think: > Yes, this is more readable, Thanks. > --- a/mm/mempolicy.c~mm-mempolicy-return-null-if-node-is-numa_no_node-in-get_task_policy > +++ a/mm/mempolicy.c > @@ -123,16 +123,19 @@ static struct mempolicy preferred_node_p > static struct mempolicy *get_task_policy(struct task_struct *p) > { > struct mempolicy *pol = p->mempolicy; > - int node; > > if (!pol) { > - node = numa_node_id(); > - if (node != NUMA_NO_NODE) > - pol = &preferred_node_policy[node]; > + int node = numa_node_id(); > > - /* preferred_node_policy is not initialised early in boot */ > - if (!pol->mode) > - pol = NULL; > + if (node != NUMA_NO_NODE) { > + pol = &preferred_node_policy[node]; > + /* > + * preferred_node_policy is not initialised early in > + * boot > + */ > + if (!pol->mode) > + pol = NULL; > + } > } > > return pol; > _ > > > . > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org