From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 4374E29DF7 for ; Tue, 15 Apr 2014 23:19:03 -0500 (CDT) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay1.corp.sgi.com (Postfix) with ESMTP id 2C0008F8052 for ; Tue, 15 Apr 2014 21:19:03 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by cuda.sgi.com with ESMTP id TYT7kMHLLaWZ8aLE (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Tue, 15 Apr 2014 21:19:02 -0700 (PDT) From: NeilBrown Date: Wed, 16 Apr 2014 14:03:36 +1000 Subject: [PATCH 10/19] NET: set PF_FSTRANS while holding sk_lock Message-ID: <20140416040336.10604.96000.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 sk_lock can be taken while reclaiming memory (in nfsd for loop-back NFS mounts, and presumably in nfs), and memory can be allocated while holding sk_lock, at least via: inet_listen -> inet_csk_listen_start ->reqsk_queue_alloc So to avoid deadlocks, always set PF_FSTRANS while holding sk_lock. This deadlock was found by lockdep. Signed-off-by: NeilBrown --- include/net/sock.h | 1 + net/core/sock.c | 2 ++ 2 files changed, 3 insertions(+) diff --git a/include/net/sock.h b/include/net/sock.h index b9586a137cad..27c355637e44 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -324,6 +324,7 @@ struct sock { #define sk_v6_rcv_saddr __sk_common.skc_v6_rcv_saddr socket_lock_t sk_lock; + unsigned int sk_pflags; /* process flags before taking lock */ struct sk_buff_head sk_receive_queue; /* * The backlog queue is special, it is always used with diff --git a/net/core/sock.c b/net/core/sock.c index cf9bd24e4099..8bc677ef072e 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2341,6 +2341,7 @@ void lock_sock_nested(struct sock *sk, int subclass) /* * The sk_lock has mutex_lock() semantics here: */ + current_set_flags_nested(&sk->sk_pflags, PF_FSTRANS); mutex_acquire(&sk->sk_lock.dep_map, subclass, 0, _RET_IP_); local_bh_enable(); } @@ -2352,6 +2353,7 @@ void release_sock(struct sock *sk) * The sk_lock has mutex_unlock() semantics: */ mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); + current_restore_flags_nested(&sk->sk_pflags, PF_FSTRANS); spin_lock_bh(&sk->sk_lock.slock); if (sk->sk_backlog.tail) _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs