Re: [PATCH AUTOSEL 5.1 004/375] NFS: make nfs_match_client killable

Benjamin Coddington
2019-05-23T15:02:49Z

Hi Sasha, if you take this one, you'll need the fix for it:

c260121a97a3 ("NFS: Fix a double unlock from nfs_match,get_client")

I didn't see this fix go through my inbox for your stable tree, so
apologies if maybe I missed it.

Looks like you are also applying this one to 4.19 and 4.14, -- I'll just
reply once here.

Ben

On 22 May 2019, at 15:15, Sasha Levin wrote:

> From: Roberto Bergantinos Corpas <rbergant@redhat.com>
>
> [ Upstream commit 950a578c6128c2886e295b9c7ecb0b6b22fcc92b ]
>
> Actually we don't do anything with return value from
> nfs_wait_client_init_complete in nfs_match_client, as a
> consequence if we get a fatal signal and client is not
> fully initialised, we'll loop to "again" label
>
> This has been proven to cause soft lockups on some scenarios
> (no-carrier but configured network interfaces)
>
> Signed-off-by: Roberto Bergantinos Corpas <rbergant@redhat.com>
> Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> fs/nfs/client.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> index 90d71fda65cec..350cfa561e0e8 100644
> --- a/fs/nfs/client.c
> +++ b/fs/nfs/client.c
> @@ -284,6 +284,7 @@ static struct nfs_client *nfs_match_client(const
> struct nfs_client_initdata *dat
> struct nfs_client *clp;
> const struct sockaddr *sap = data->addr;
> struct nfs_net *nn = net_generic(data->net, nfs_net_id);
> + int error;
>
> again:
> list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) {
> @@ -296,8 +297,10 @@ static struct nfs_client *nfs_match_client(const
> struct nfs_client_initdata *dat
> if (clp->cl_cons_state > NFS_CS_READY) {
> refcount_inc(&clp->cl_count);
> spin_unlock(&nn->nfs_client_lock);
> - nfs_wait_client_init_complete(clp);
> + error = nfs_wait_client_init_complete(clp);
> nfs_put_client(clp);
> + if (error < 0)
> + return ERR_PTR(error);
> spin_lock(&nn->nfs_client_lock);
> goto again;
> }
> @@ -407,6 +410,8 @@ struct nfs_client *nfs_get_client(const struct
> nfs_client_initdata *cl_init)
> clp = nfs_match_client(cl_init);
> if (clp) {
> spin_unlock(&nn->nfs_client_lock);
> + if (IS_ERR(clp))
> + return clp;
> if (new)
> new->rpc_ops->free_client(new);
> return nfs_found_client(cl_init, clp);
> --
> 2.20.1