From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4267C433E0 for ; Wed, 24 Jun 2020 01:29:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 491312098B for ; Wed, 24 Jun 2020 01:29:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fieldses.org header.i=@fieldses.org header.b="ONFYh/dH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388422AbgFXB3C (ORCPT ); Tue, 23 Jun 2020 21:29:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387842AbgFXB3C (ORCPT ); Tue, 23 Jun 2020 21:29:02 -0400 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C8CEC061573 for ; Tue, 23 Jun 2020 18:29:02 -0700 (PDT) Received: by fieldses.org (Postfix, from userid 2815) id B6A999238; Tue, 23 Jun 2020 21:29:01 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org B6A999238 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1592962141; bh=iAGgI5588NX5gPvO7FsqFjqFQ8ZS8KJ28FbnQFG3Lhk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ONFYh/dHz3IQBn2Ut8hXriQSVgkVPs2DyZ2GcrwUZ8bI5mA2VBCBCZSne3P8h0AhR ijP3f9TPNMqfSkTeKZ0kzzOgRl5pOotxaNKz37t1SQIAJbvBim34ZsiEbRHEWVVbhQ FjwAB5sJAPcVI5QHAFksF48lXNilQkomrY2ObWRg= Date: Tue, 23 Jun 2020 21:29:01 -0400 From: "J. Bruce Fields" To: Luo Xiaogang Cc: chuck.lever@oracle.com, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] nfsd: fix kernel crash when load nfsd in docker Message-ID: <20200624012901.GC18460@fieldses.org> References: <20200615071211.31326-1-lxgrxd@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200615071211.31326-1-lxgrxd@163.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Mon, Jun 15, 2020 at 03:12:11PM +0800, Luo Xiaogang wrote: > We load nfsd module in the docker container, kernel crash as following. > > The 'current->nsproxy->net_ns->gen->ptr[nfsd_net_id]' is overflow in the > nfsd_init_net. > > We should use the net_ns which is being init in the nfsd_init_net, > not the 'current->nsproxy->net_ns'. Thanks! Actually, I think my problem was that net init and exit are just the wrong place to be doing this--I moved them to nfsd start/stop instead. And then that exposed the fact that I had an inode leak. Do the following two patches help? --b. >From 16f954bd5c481596a63271a91963bf260e2f3f46 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Tue, 23 Jun 2020 16:00:33 -0400 Subject: [PATCH 1/2] nfsd4: fix nfsdfs reference count loop We don't drop the reference on the nfsdfs filesystem with mntput(nn->nfsd_mnt) until nfsd_exit_net(), but that won't be called until the nfsd module's unloaded, and we can't unload the module as long as there's a reference on nfsdfs. So this prevents module unloading. Signed-off-by: J. Bruce Fields --- fs/nfsd/nfs4state.c | 8 +++++++- fs/nfsd/nfsctl.c | 22 ++++++++++++---------- fs/nfsd/nfsd.h | 3 +++ 3 files changed, 22 insertions(+), 11 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index bb3d2c32664a..cce2510b2cca 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -7912,9 +7912,14 @@ nfs4_state_start_net(struct net *net) struct nfsd_net *nn = net_generic(net, nfsd_net_id); int ret; - ret = nfs4_state_create_net(net); + ret = get_nfsdfs(net); if (ret) return ret; + ret = nfs4_state_create_net(net); + if (ret) { + mntput(nn->nfsd_mnt); + return ret; + } locks_start_grace(net, &nn->nfsd4_manager); nfsd4_client_tracking_init(net); if (nn->track_reclaim_completes && nn->reclaim_str_hashtbl_size == 0) @@ -7984,6 +7989,7 @@ nfs4_state_shutdown_net(struct net *net) nfsd4_client_tracking_exit(net); nfs4_state_destroy_net(net); + mntput(nn->nfsd_mnt); } void diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index b68e96681522..cf98a81ca1ea 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1424,6 +1424,18 @@ static struct file_system_type nfsd_fs_type = { }; MODULE_ALIAS_FS("nfsd"); +int get_nfsdfs(struct net *net) +{ + struct nfsd_net *nn = net_generic(net, nfsd_net_id); + struct vfsmount *mnt; + + mnt = vfs_kern_mount(&nfsd_fs_type, SB_KERNMOUNT, "nfsd", NULL); + if (IS_ERR(mnt)) + return PTR_ERR(mnt); + nn->nfsd_mnt = mnt; + return 0; +} + #ifdef CONFIG_PROC_FS static int create_proc_exports_entry(void) { @@ -1451,7 +1463,6 @@ unsigned int nfsd_net_id; static __net_init int nfsd_init_net(struct net *net) { int retval; - struct vfsmount *mnt; struct nfsd_net *nn = net_generic(net, nfsd_net_id); retval = nfsd_export_init(net); @@ -1478,16 +1489,8 @@ static __net_init int nfsd_init_net(struct net *net) init_waitqueue_head(&nn->ntf_wq); seqlock_init(&nn->boot_lock); - mnt = vfs_kern_mount(&nfsd_fs_type, SB_KERNMOUNT, "nfsd", NULL); - if (IS_ERR(mnt)) { - retval = PTR_ERR(mnt); - goto out_mount_err; - } - nn->nfsd_mnt = mnt; return 0; -out_mount_err: - nfsd_reply_cache_shutdown(nn); out_drc_error: nfsd_idmap_shutdown(net); out_idmap_error: @@ -1500,7 +1503,6 @@ static __net_exit void nfsd_exit_net(struct net *net) { struct nfsd_net *nn = net_generic(net, nfsd_net_id); - mntput(nn->nfsd_mnt); nfsd_reply_cache_shutdown(nn); nfsd_idmap_shutdown(net); nfsd_export_shutdown(net); diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h index 36cdd81b6688..57c832d1b30f 100644 --- a/fs/nfsd/nfsd.h +++ b/fs/nfsd/nfsd.h @@ -90,6 +90,8 @@ void nfsd_destroy(struct net *net); bool i_am_nfsd(void); +int get_nfsdfs(struct net *); + struct nfsdfs_client { struct kref cl_ref; void (*cl_release)(struct kref *kref); @@ -100,6 +102,7 @@ struct dentry *nfsd_client_mkdir(struct nfsd_net *nn, struct nfsdfs_client *ncl, u32 id, const struct tree_descr *); void nfsd_client_rmdir(struct dentry *dentry); + #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) #ifdef CONFIG_NFSD_V2_ACL extern const struct svc_version nfsd_acl_version2; -- 2.26.2 >From 51de3b460b39e862f7dcfd4d600e8de0afe73e29 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Tue, 23 Jun 2020 21:01:19 -0400 Subject: [PATCH 2/2] nfsd: fix nfsdfs inode reference count leak I don't understand this code well, but I'm seeing a warning about a still-referenced inode on unmount, and every other similar filesystem does a dput() here. Signed-off-by: J. Bruce Fields --- fs/nfsd/nfsctl.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index cf98a81ca1ea..cd05732f8eaa 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1335,6 +1335,7 @@ void nfsd_client_rmdir(struct dentry *dentry) WARN_ON_ONCE(ret); fsnotify_rmdir(dir, dentry); d_delete(dentry); + dput(dentry); inode_unlock(dir); } -- 2.26.2