Re: [PATCH] cifs: Fix oops due to uncleared server->smbd_conn in reconnect

[Tom Talpey <tom@talpey.com>]

On 1/25/2023 9:02 AM, David Howells wrote:
> Hi Steve,
> 
> That attached patch stops the kernel from oopsing, but it still tries
> endlessly to send with softRoCE.  I'm having better luck with softIWarp - with
> some other patches, I can run generic/001 to completion with that transport.

Do you have any logging from the softRoCE runs? I'd suspect some
kind of RDMA-specific scatter/gather overflow which might be
server-side as easily as client-side.

On client, try:
   echo 0x1ff >/sys/module/cifs/parameters/smbd_logging_class

On server:
    ksmbd.control -d conn
    ksmbd.control -d rdma

> ---
> commit 820cb3802c6a73c54e2e215b674eb5870fd5d0e5
> Author: David Howells <dhowells@redhat.com>
> Date:   Wed Jan 25 12:42:07 2023 +0000
> 
>      cifs: Fix oops due to uncleared server->smbd_conn in reconnect
>      
>      In smbd_destroy(), clear the server->smbd_conn pointer after freeing the
>      smbd_connection struct that it points to so that reconnection doesn't get
>      confused.
>      
>      Fixes: 8ef130f9ec27 ("CIFS: SMBD: Implement function to destroy a SMB Direct connection")
>      Signed-off-by: David Howells <dhowells@redhat.com>
>      cc: Long Li <longli@microsoft.com>
>      cc: Steve French <smfrench@gmail.com>
>      cc: Pavel Shilovsky <pshilov@microsoft.com>
>      cc: Ronnie Sahlberg <lsahlber@redhat.com>
>      cc: linux-cifs@vger.kernel.org
> 
> diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
> index 90789aaa6567..8c816b25ce7c 100644
> --- a/fs/cifs/smbdirect.c
> +++ b/fs/cifs/smbdirect.c
> @@ -1405,6 +1405,7 @@ void smbd_destroy(struct TCP_Server_Info *server)
>   	destroy_workqueue(info->workqueue);
>   	log_rdma_event(INFO,  "rdma session destroyed\n");
>   	kfree(info);
> +	server->smbd_conn = NULL;
>   }
>   
>   /*
> 
>