Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757923AbXITRIT (ORCPT ); Thu, 20 Sep 2007 13:08:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753434AbXITRIL (ORCPT ); Thu, 20 Sep 2007 13:08:11 -0400 Received: from mtagate8.de.ibm.com ([195.212.29.157]:2866 "EHLO mtagate8.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751839AbXITRIK (ORCPT ); Thu, 20 Sep 2007 13:08:10 -0400 Message-ID: <46F2A8F6.4080508@fr.ibm.com> Date: Thu, 20 Sep 2007 19:08:06 +0200 From: Cedric Le Goater User-Agent: Thunderbird 2.0.0.5 (X11/20070727) MIME-Version: 1.0 To: Cedric Le Goater CC: Pavel Emelyanov , Andrew Morton , linux-kernel@vger.kernel.org, "Serge E. Hallyn" , "Eric W. Biederman" , Oleg Nesterov , "Paul E. McKenney" Subject: Re: 2.6.23-rc6-mm1 - make access to tasks nsproxy ligther (fix) References: <20070918011841.2381bd93.akpm@linux-foundation.org> <46F2324E.9020707@fr.ibm.com> <46F23681.2030400@openvz.org> <46F2396D.7090404@fr.ibm.com> In-Reply-To: <46F2396D.7090404@fr.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3629 Lines: 123 Cedric Le Goater wrote: > Pavel Emelyanov wrote: >> Looks sane :) >> >> [snip] >> >>> Index: 2.6.23-rc6-mm1/kernel/exit.c >>> =================================================================== >>> --- 2.6.23-rc6-mm1.orig/kernel/exit.c >>> +++ 2.6.23-rc6-mm1/kernel/exit.c >>> @@ -408,6 +408,8 @@ void daemonize(const char *name, ...) >>> current->fs = fs; >>> atomic_inc(&fs->count); >>> >>> + if (current->nsproxy != init_task.nsproxy) >>> + get_nsproxy(init_task.nsproxy); >>> switch_task_namespaces(current, init_task.nsproxy); >> shouldn't we make the switch under this if() as well? > > right. we can probably simplify switch_task_namespaces() and remove : > > if (ns == new) > return; > > I'll cook a better one today. So I removed this test in * daemonize() bc it is already done * sys_unshare() bc the nsproxy is always new one * exit_task_namespaces() bc it is called with NULL and the task will die right after that. C. make-access-to-tasks-nsproxy-lighter.patch breaks unshare() when called from unshare(), switch_task_namespaces() takes an extra refcount on the nsproxy, leading to a memory leak of nsproxy objects. Now the problem is that we still need that extra ref when called from daemonize(). Here's an ugly fix for it. Signed-off-by: Cedric Le Goater Cc: Serge E. Hallyn Cc: Pavel Emelyanov Cc: Eric W. Biederman Cc: Oleg Nesterov Cc: Paul E. McKenney --- include/linux/nsproxy.h | 5 +++++ kernel/exit.c | 5 ++++- kernel/nsproxy.c | 9 --------- 3 files changed, 9 insertions(+), 10 deletions(-) Index: 2.6.23-rc6-mm1/kernel/nsproxy.c =================================================================== --- 2.6.23-rc6-mm1.orig/kernel/nsproxy.c +++ 2.6.23-rc6-mm1/kernel/nsproxy.c @@ -25,11 +25,6 @@ static struct kmem_cache *nsproxy_cachep struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy); -static inline void get_nsproxy(struct nsproxy *ns) -{ - atomic_inc(&ns->count); -} - /* * creates a copy of "orig" with refcount 1. */ @@ -205,11 +200,7 @@ void switch_task_namespaces(struct task_ might_sleep(); ns = p->nsproxy; - if (ns == new) - return; - if (new) - get_nsproxy(new); rcu_assign_pointer(p->nsproxy, new); if (ns && atomic_dec_and_test(&ns->count)) { Index: 2.6.23-rc6-mm1/kernel/exit.c =================================================================== --- 2.6.23-rc6-mm1.orig/kernel/exit.c +++ 2.6.23-rc6-mm1/kernel/exit.c @@ -408,7 +408,10 @@ void daemonize(const char *name, ...) current->fs = fs; atomic_inc(&fs->count); - switch_task_namespaces(current, init_task.nsproxy); + if (current->nsproxy != init_task.nsproxy) { + get_nsproxy(init_task.nsproxy); + switch_task_namespaces(current, init_task.nsproxy); + } exit_files(current); current->files = init_task.files; Index: 2.6.23-rc6-mm1/include/linux/nsproxy.h =================================================================== --- 2.6.23-rc6-mm1.orig/include/linux/nsproxy.h +++ 2.6.23-rc6-mm1/include/linux/nsproxy.h @@ -77,6 +77,11 @@ static inline void put_nsproxy(struct ns } } +static inline void get_nsproxy(struct nsproxy *ns) +{ + atomic_inc(&ns->count); +} + #ifdef CONFIG_CONTAINER_NS int ns_container_clone(struct task_struct *tsk); #else - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/