2014-08-14 22:49:54

by Cong Wang

Subject: [PATCH] nfs: fix kernel warning when removing proc entry

I saw the following kernel warning:

[ 1852.321222] ------------[ cut here ]------------
[ 1852.326527] WARNING: CPU: 0 PID: 118 at fs/proc/generic.c:521 remove_proc_entry+0x154/0x16b()
[ 1852.335630] remove_proc_entry: removing non-empty directory 'fs/nfsfs', leaking at least 'volumes'
[ 1852.344084] CPU: 0 PID: 118 Comm: kworker/u8:2 Not tainted 3.16.0+ #540
[ 1852.350036] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 1852.354992] Workqueue: netns cleanup_net
[ 1852.358701] 0000000000000000 ffff880116f2fbd0 ffffffff819c03e9 ffff880116f2fc18
[ 1852.366474] ffff880116f2fc08 ffffffff810744ee ffffffff811e0e6e ffff8800d4e96238
[ 1852.373507] ffffffff81dbe665 ffff8800d46a5948 0000000000000005 ffff880116f2fc68
[ 1852.380224] Call Trace:
[ 1852.381976] [<ffffffff819c03e9>] dump_stack+0x4d/0x66
[ 1852.385495] [<ffffffff810744ee>] warn_slowpath_common+0x7a/0x93
[ 1852.389869] [<ffffffff811e0e6e>] ? remove_proc_entry+0x154/0x16b
[ 1852.393987] [<ffffffff8107457b>] warn_slowpath_fmt+0x4c/0x4e
[ 1852.397999] [<ffffffff811e0e6e>] remove_proc_entry+0x154/0x16b
[ 1852.402034] [<ffffffff8129c73d>] nfs_fs_proc_net_exit+0x53/0x56
[ 1852.406136] [<ffffffff812a103b>] nfs_net_exit+0x12/0x1d
[ 1852.409774] [<ffffffff81785bc9>] ops_exit_list+0x44/0x55
[ 1852.413529] [<ffffffff81786389>] cleanup_net+0xee/0x182
[ 1852.417198] [<ffffffff81088c9e>] process_one_work+0x209/0x40d
[ 1852.502320] [<ffffffff81088bf7>] ? process_one_work+0x162/0x40d
[ 1852.587629] [<ffffffff810890c1>] worker_thread+0x1f0/0x2c7
[ 1852.673291] [<ffffffff81088ed1>] ? process_scheduled_works+0x2f/0x2f
[ 1852.759470] [<ffffffff8108e079>] kthread+0xc9/0xd1
[ 1852.843099] [<ffffffff8109427f>] ? finish_task_switch+0x3a/0xce
[ 1852.926518] [<ffffffff8108dfb0>] ? __kthread_parkme+0x61/0x61
[ 1853.008565] [<ffffffff819cbeac>] ret_from_fork+0x7c/0xb0
[ 1853.076477] [<ffffffff8108dfb0>] ? __kthread_parkme+0x61/0x61
[ 1853.140653] ---[ end trace 69c4c6617f78e32d ]---

It looks wrong that we add "/proc/net/nfsfs" in nfs_fs_proc_net_init()
while remove "/proc/fs/nfsfs" in nfs_fs_proc_net_exit().

Fixes: commit 65b38851a17 (NFS: Fix /proc/fs/nfsfs/servers and /proc/fs/nfsfs/volumes)
Cc: Eric W. Biederman <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Stanislav Kinsbursky <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
---
fs/nfs/client.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 1c5ff6d..1c57202 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -1429,7 +1429,7 @@ void nfs_fs_proc_net_exit(struct net *net)

remove_proc_entry("volumes", nn->proc_nfsfs);
remove_proc_entry("servers", nn->proc_nfsfs);
- remove_proc_entry("fs/nfsfs", NULL);
+ remove_proc_entry("nfsfs", net->proc_net);
}

/*
--
1.8.3.1

2014-08-16 17:56:58

by Dan Aloni

Subject: Re: [PATCH] nfs: fix kernel warning when removing proc entry

On Thu, Aug 14, 2014 at 03:49:39PM -0700, Cong Wang wrote:
Signed-off-by: Cong Wang <[email protected]>
> ---
> fs/nfs/client.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> index 1c5ff6d..1c57202 100644
> --- a/fs/nfs/client.c
> +++ b/fs/nfs/client.c
> @@ -1429,7 +1429,7 @@ void nfs_fs_proc_net_exit(struct net *net)
>
> remove_proc_entry("volumes", nn->proc_nfsfs);
> remove_proc_entry("servers", nn->proc_nfsfs);
> - remove_proc_entry("fs/nfsfs", NULL);
> + remove_proc_entry("nfsfs", net->proc_net);
> }

nfs_fs_proc_net_init() has:

error_1:
remove_proc_entry("fs/nfsfs", NULL);

I think this needs fixing too, for consistency.

--
Dan Aloni