From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 1AE8C29DF7 for ; Tue, 15 Apr 2014 23:19:19 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay2.corp.sgi.com (Postfix) with ESMTP id E6BE5304077 for ; Tue, 15 Apr 2014 21:19:18 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by cuda.sgi.com with ESMTP id LGMoKAyEkJ1yCiEi (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Tue, 15 Apr 2014 21:19:16 -0700 (PDT) From: NeilBrown Date: Wed, 16 Apr 2014 14:03:36 +1000 Subject: [PATCH 12/19] NET: set PF_FSTRANS while holding rtnl_lock Message-ID: <20140416040336.10604.81658.stgit@notabene.brown> In-Reply-To: <20140416033623.10604.69237.stgit@notabene.brown> References: <20140416033623.10604.69237.stgit@notabene.brown> MIME-Version: 1.0 List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: linux-mm@kvack.org, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org, xfs@oss.sgi.com As rtnl_mutex can be taken while holding sk_lock, and sk_lock can be taken while performing memory reclaim (at least when loop-back NFS is active), any memory allocation under rtnl_mutex must avoid __GFP_FS, which is most easily done by setting PF_MEMALLOC. CPU0 CPU1 ---- ---- lock(rtnl_mutex); lock(sk_lock-AF_INET); lock(rtnl_mutex); lock(sk_lock-AF_INET); *** DEADLOCK *** 1/ rtnl_mutex is taken while holding sk_lock: [] rtnl_lock+0x12/0x20 [] ip_mc_leave_group+0x2a/0x160 [] do_ip_setsockopt.isra.18+0x96b/0xed0 [] ip_setsockopt+0x27/0x90 [] udp_setsockopt+0x16/0x30 [] sock_common_setsockopt+0xf/0x20 [] SyS_setsockopt+0x5e/0xc0 2/ memory is allocated under rtnl_mutex: [] kobject_set_name_vargs+0x21/0x70 [] dev_set_name+0x42/0x50 [] netdev_register_kobject+0x57/0x130 [] register_netdevice+0x354/0x550 [] register_netdev+0x15/0x30 Signed-off-by: NeilBrown --- net/core/rtnetlink.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 120eecc0f5a4..6870211e93a6 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -61,15 +61,18 @@ struct rtnl_link { }; static DEFINE_MUTEX(rtnl_mutex); +static int rtnl_pflags; void rtnl_lock(void) { mutex_lock(&rtnl_mutex); + current_set_flags_nested(&rtnl_pflags, PF_FSTRANS); } EXPORT_SYMBOL(rtnl_lock); void __rtnl_unlock(void) { + current_restore_flags_nested(&rtnl_pflags, PF_FSTRANS); mutex_unlock(&rtnl_mutex); } @@ -82,7 +85,11 @@ EXPORT_SYMBOL(rtnl_unlock); int rtnl_trylock(void) { - return mutex_trylock(&rtnl_mutex); + if (mutex_trylock(&rtnl_mutex)) { + current_set_flags_nested(&rtnl_pflags, PF_FSTRANS); + return 1; + } + return 0; } EXPORT_SYMBOL(rtnl_trylock); _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs