From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sowmini Varadhan Subject: Re: WARN_ON in commit 0ffdaf5 "net/sock: add WARN_ON(parent->sk) in sock_graft()" Date: Fri, 4 Aug 2017 07:19:29 -0400 Message-ID: <20170804111929.GD16796@oracle.com> References: <598456CE.7020702@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: davem@davemloft.net, netdev@vger.kernel.org To: Guoqing Jiang Return-path: Received: from userp1040.oracle.com ([156.151.31.81]:35936 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751342AbdHDLTk (ORCPT ); Fri, 4 Aug 2017 07:19:40 -0400 Content-Disposition: inline In-Reply-To: <598456CE.7020702@suse.com> Sender: netdev-owner@vger.kernel.org List-ID: On (08/04/17 19:13), Guoqing Jiang wrote: > > HI, > > With commit 0ffdaf5b41cf4435ece14d1d3e977ce69012a20d "net/sock: add > WARN_ON(parent->sk) in sock_graft()", > I can see the WARN_ON is triggered easily by dlm subsystem. > > tcp_accept_from_sock() in fs/dlm/lowcomms.c has the following snippet: > > 1. result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family, > SOCK_STREAM, IPPROTO_TCP, &newsock); > sk is set by the path "sock_create_kern -> __sock_creat -> > pf->create => inet_create -> sock_init_data" > ... > 2. result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK, true); > Then sock_graft is called by "con->sock->ops->accept => inet_accept > -> sock_graft " > > Does it mean call accept() after the just created socket is not a acceptable > behavior? Any comment will be appreciate, thanks. > It means that you have a sk leak, just like rds-tcp did. See https://patchwork.ozlabs.org/patch/780356/ for a discussion. You should be calling sock_create_lite, instead of sock_create_kern. The ->sk that triggers the WARN_ON is the one that is leaking (you will see that the ->sk befrore the ->accept (i.e., the one set up by sock_create_kern) is different than the one after ->accept) --Sowmini