From mboxrd@z Thu Jan 1 00:00:00 1970 From: "N.C.Krishna Murthy" Subject: Re:Request for review of Linux iSCSI driver version 4.0.0.1 Date: Thu, 11 Dec 2003 21:17:46 +0530 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <200312112117.46216.krmurthy@cisco.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Return-path: Received: from india-ironport-1.cisco.com ([64.104.129.195]:65356 "EHLO india-ironport-1.cisco.com") by vger.kernel.org with ESMTP id S265133AbTLKPry convert rfc822-to-8bit (ORCPT ); Thu, 11 Dec 2003 10:47:54 -0500 List-Id: linux-scsi@vger.kernel.org To: Christoph Hellwig Cc: SCSI -DEVEL , davmyers@cisco.com Hi, One of your comments was "having multiple kmap() in the same process at the same time can deadlock(), you redesign iscsi_xmit_task/iscsi_xmit_data/iscsi_recv_data not to do that. for the tx path use ->sendpage to avoid a data copy and kmapping altogether". I did try using sendpage in iscsi_xmit_data. Whenever the scatterlist->length was 4096 sendpage did succeed. When it was 8192 I did see a panic ------------------------------------------------------------------------------------------ Unable to handle kernel NULL pointer dereference at virtual address 00000004 Dec 11 08:55:22 linux-3 kernel: printing eip: Dec 11 08:55:22 linux-3 kernel: c03e24ec Dec 11 08:55:22 linux-3 kernel: *pde = 00000000 Dec 11 08:55:22 linux-3 kernel: Oops: 0002 [#1] Dec 11 08:55:22 linux-3 kernel: CPU: 0 Dec 11 08:55:22 linux-3 kernel: EIP: 0060:[__func__.4+49981/364885] Not ta inted Dec 11 08:55:22 linux-3 kernel: EIP: 0060:[] Not tainted Dec 11 08:55:22 linux-3 kernel: EFLAGS: 00010287 Dec 11 08:55:22 linux-3 kernel: EIP is at do_tcp_sendpages+0x62e/0xb8a ------------------------------------------------------------------------------------------ Has this been seen earlier? Thanx N.C.Krishna Murthy