Re:Request for review of Linux iSCSI driver version 4.0.0.1

["N.C.Krishna Murthy" <krmurthy@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:[<c03e24ec>]    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