From patchwork Mon Oct 30 14:54:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vasily Averin X-Patchwork-Id: 10032717 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 024A7603B4 for ; Mon, 30 Oct 2017 14:55:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E36BB283AF for ; Mon, 30 Oct 2017 14:54:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D769128478; Mon, 30 Oct 2017 14:54:59 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E86B5283AF for ; Mon, 30 Oct 2017 14:54:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752062AbdJ3Oy5 (ORCPT ); Mon, 30 Oct 2017 10:54:57 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:40131 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751894AbdJ3Oy4 (ORCPT ); Mon, 30 Oct 2017 10:54:56 -0400 Received: from [172.16.24.21] (msk-vpn.virtuozzo.com [195.214.232.6]) by relay.sw.ru (8.13.4/8.13.4) with ESMTP id v9UEskDM003101; Mon, 30 Oct 2017 17:54:46 +0300 (MSK) From: Vasily Averin Subject: [PATCH] lockd: fix lockd shutdown race with signal To: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jeff Layton , "J. Bruce Fields" , David Jeffery Message-ID: Date: Mon, 30 Oct 2017 17:54:46 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 Content-Language: en-US Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Commit efda760fe95ea ("lockd: fix lockd shutdown race") is incorrect, it removes grace a) for init_net only b) only on stop of lockd kernel thread If we start nfsd from another net namespace lockd_up_net() calls set_grace_period() that adds lockd_manager into per-netns list. Then we stop nfsd server. If lockd have another users it will not be destroyed and lock_manager will not be removed from list. If lockd had no other users then lockd kernel thread will be stopped, but "remove" lock_manager strongly from init_net. When nfsd in net namespace will started again we get "list_add double add" error. Reproducer: - do not start nfsd on host - create new net namespace # unshare -n -m ; mount -t nfsd nfsd /proc/fs/nfsd - start nfsd from newly created net namespace # echo 1 > /proc/fs/nfsd/threads - stop and restart it again # echo 0 > /proc/fs/nfsd/thread # echo 1 > /proc/fs/nfsd/thread Result: "list_add double add" in set_grace_period() [ 414.644407] NFSD: attempt to initialize umh client tracking in a container ignored. [ 414.644533] NFSD: attempt to initialize legacy client tracking in a container ignored. [ 414.644562] NFSD: Unable to initialize client recovery tracking! (-22) [ 414.644585] NFSD: starting 90-second grace period (net ffff8df8f0243140) <<< 1st start [ 423.788079] nfsd: last server has exited, flushing export cache <<< stop [ 426.735772] list_add double add: new=ffff8df8f1db1310, prev=ffff8df93cac9348, next=ffff8df8f1db1310. [ 426.735833] ------------[ cut here ]------------ <<< 2nd start [ 426.735855] kernel BUG at lib/list_debug.c:31! [ 426.735876] invalid opcode: 0000 [#1] SMP [ 426.736011] CPU: 5 PID: 1423 Comm: bash Not tainted 4.14.0-rc6+ #2 [ 426.736011] Hardware name: Virtuozzo KVM, BIOS 1.9.1-5.3.2.vz7.7 04/01/2014 [ 426.736011] task: ffff8df8f2278040 task.stack: ffffa70b40ce4000 [ 426.736011] RIP: 0010:__list_add_valid+0x66/0x70 [ 426.736011] RSP: 0018:ffffa70b40ce7ce8 EFLAGS: 00010282 [ 426.736011] RAX: 0000000000000058 RBX: ffff8df8f1db1310 RCX: 0000000000000000 [ 426.736011] RDX: 0000000000000000 RSI: ffff8df93fd4e138 RDI: ffff8df93fd4e138 [ 426.736011] RBP: ffffa70b40ce7ce8 R08: 00000000000002ba R09: 0000000000000000 [ 426.736011] R10: 0000000000000010 R11: 00000000ffffffff R12: ffff8df93cac9348 [ 426.736011] R13: ffff8df8f1db1310 R14: ffff8df8f0243140 R15: 0000000000000000 [ 426.736011] FS: 00007f8c9389db40(0000) GS:ffff8df93fd40000(0000) knlGS:0000000000000000 [ 426.736011] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 426.736011] CR2: 00007f8c936848d0 CR3: 000000007ca88003 CR4: 00000000001606e0 [ 426.736011] Call Trace: [ 426.736011] locks_start_grace+0x40/0x70 [grace] [ 426.736011] set_grace_period+0x44/0x90 [lockd] [ 426.736011] lockd_up+0x2b2/0x350 [lockd] [ 426.736011] nfsd_svc+0x256/0x2b0 [nfsd] [ 426.736011] ? write_pool_threads+0x2b0/0x2b0 [nfsd] [ 426.736011] write_threads+0x80/0xe0 [nfsd] [ 426.736011] ? simple_transaction_get+0xb5/0xd0 [ 426.736011] nfsctl_transaction_write+0x48/0x80 [nfsd] [ 426.736011] __vfs_write+0x37/0x170 [ 426.736011] ? selinux_file_permission+0x105/0x120 [ 426.736011] ? security_file_permission+0x3b/0xc0 [ 426.736011] vfs_write+0xb1/0x1a0 [ 426.736011] SyS_write+0x55/0xc0 Before commit efda760fe95ea "lockd: fix lockd shutdown race" lock_manager was removed from correct net namespace. This patch reverts efda760fe95ea "lockd: fix lockd shutdown race" and introduces stop_grace() function that is called in all rollback cases and correctly removes lock_manager. The patch still resolves the problem fixed by reverted patch: now final final locks_end_grace() is called not before but after stop of lockd kernel thread. Fixes commit efda760fe95e ("lockd: fix lockd shutdown race") Signed-off-by: Vasily Averin --- fs/lockd/svc.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c index c1573860..d14e0f9 100644 --- a/fs/lockd/svc.c +++ b/fs/lockd/svc.c @@ -127,6 +127,16 @@ static void restart_grace(void) } } +static void stop_grace(struct net *net) +{ + struct lockd_net *ln = net_generic(net, lockd_net_id); + + if (ln->nlmsvc_users == 0) { + cancel_delayed_work_sync(&ln->grace_period_end); + locks_end_grace(&ln->lockd_manager); + } +} + /* * This is the lockd kernel thread */ @@ -135,8 +145,6 @@ lockd(void *vrqstp) { int err = 0; struct svc_rqst *rqstp = vrqstp; - struct net *net = &init_net; - struct lockd_net *ln = net_generic(net, lockd_net_id); /* try_to_freeze() is called from svc_recv() */ set_freezable(); @@ -181,8 +189,6 @@ lockd(void *vrqstp) if (nlmsvc_ops) nlmsvc_invalidate_all(); nlm_shutdown_hosts(); - cancel_delayed_work_sync(&ln->grace_period_end); - locks_end_grace(&ln->lockd_manager); return 0; } @@ -480,6 +486,7 @@ int lockd_up(struct net *net) error = lockd_start_svc(serv); if (error < 0) { lockd_down_net(serv, net); + stop_grace(net); goto err_put; } nlmsvc_users++; @@ -504,8 +511,10 @@ lockd_down(struct net *net) mutex_lock(&nlmsvc_mutex); lockd_down_net(nlmsvc_rqst->rq_server, net); if (nlmsvc_users) { - if (--nlmsvc_users) + if (--nlmsvc_users) { + stop_grace(net); goto out; + } } else { printk(KERN_ERR "lockd_down: no users! task=%p\n", nlmsvc_task); @@ -517,6 +526,7 @@ lockd_down(struct net *net) BUG(); } kthread_stop(nlmsvc_task); + stop_grace(net); dprintk("lockd_down: service stopped\n"); lockd_svc_exit_thread(); dprintk("lockd_down: service destroyed\n");