From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4509C38B.3000808@cs.wisc.edu> Date: Thu, 14 Sep 2006 16:03:07 -0500 From: Mike Christie MIME-Version: 1.0 Subject: Re: [PATCH 20/20] iscsi: support for swapping over iSCSI. References: <20060912143049.278065000@chello.nl> <20060912144905.201160000@chello.nl> <45086F16.9030307@cs.wisc.edu> <1158214650.13665.27.camel@twins> <4509ABE5.2080904@cs.wisc.edu> <1158266150.30737.92.camel@taijtu> <4509C2DF.8000007@cs.wisc.edu> In-Reply-To: <4509C2DF.8000007@cs.wisc.edu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Linus Torvalds , Andrew Morton , David Miller , Rik van Riel , Daniel Phillips List-ID: Mike Christie wrote: > Peter Zijlstra wrote: >> On Thu, 2006-09-14 at 14:22 -0500, Mike Christie wrote: >>> Peter Zijlstra wrote: >>>> On Wed, 2006-09-13 at 15:50 -0500, Mike Christie wrote: >>>>> Peter Zijlstra wrote: >>>>>> Implement sht->swapdev() for iSCSI. This method takes care of reserving >>>>>> the extra memory needed and marking all relevant sockets with SOCK_VMIO. >>>>>> >>>>>> When used for swapping, TCP socket creation is done under GFP_MEMALLOC and >>>>>> the TCP connect is done with SOCK_VMIO to ensure their success. Also the >>>>>> netlink userspace interface is marked SOCK_VMIO, this will ensure that even >>>>>> under pressure we can still communicate with the daemon (which runs as >>>>>> mlockall() and needs no additional memory to operate). >>>>>> >>>>>> Netlink requests are handled under the new PF_MEM_NOWAIT when a swapper is >>>>>> present. This ensures that the netlink socket will not block. User-space will >>>>>> need to retry failed requests. >>>>>> >>>>>> The TCP receive path is handled under PF_MEMALLOC for SOCK_VMIO sockets. >>>>>> This makes sure we do not block the critical socket, and that we do not >>>>>> fail to process incomming data. >>>>>> >>>>>> Signed-off-by: Peter Zijlstra >>>>>> CC: Mike Christie >>>>>> --- >>>>>> drivers/scsi/iscsi_tcp.c | 103 +++++++++++++++++++++++++++++++----- >>>>>> drivers/scsi/scsi_transport_iscsi.c | 23 +++++++- >>>>>> include/scsi/libiscsi.h | 1 >>>>>> include/scsi/scsi_transport_iscsi.h | 2 >>>>>> 4 files changed, 113 insertions(+), 16 deletions(-) >>>>>> >>>>>> Index: linux-2.6/drivers/scsi/iscsi_tcp.c >>>>>> =================================================================== >>>>>> --- linux-2.6.orig/drivers/scsi/iscsi_tcp.c >>>>>> +++ linux-2.6/drivers/scsi/iscsi_tcp.c >>>>>> @@ -42,6 +42,7 @@ >>>>>> #include >>>>>> #include >>>>>> #include >>>>>> +#include >>>>>> >>>>>> #include "iscsi_tcp.h" >>>>>> >>>>>> @@ -845,9 +846,13 @@ iscsi_tcp_data_recv(read_descriptor_t *r >>>>>> int rc; >>>>>> struct iscsi_conn *conn = rd_desc->arg.data; >>>>>> struct iscsi_tcp_conn *tcp_conn = conn->dd_data; >>>>>> - int processed; >>>>>> + int processed = 0; >>>>>> char pad[ISCSI_PAD_LEN]; >>>>>> struct scatterlist sg; >>>>>> + unsigned long pflags = current->flags; >>>>>> + >>>>>> + if (sk_has_vmio(tcp_conn->sock->sk)) >>>>>> + current->flags |= PF_MEMALLOC; >>>>>> >>>>> Is this too late or not needed or what is it for? This function gets run >>>>> from the network layer's softirq and at this point we have a skbuff with >>>>> data that we want to process. The iscsi layer also does not allocate >>>>> memory for read or write IO in this path. >>>> I thought I found allocations in that path, lemme search... >>>> found this: >>>> >>>> iscsi_tcp_data_recv() >>>> iscsi_data_rescv() >>>> iscsi_complete_pdu() >>>> __iscsi_complete_pdu() >>>> iscsi_recv_pdu() >>>> alloc_skb( GFP_ATOMIC); >>>> >>> You are right that is for the netlink interface. Could we move the >>> PF_MEMALLOC setting and clearing to iscsi_recv_pdu and and add it to >>> iscsi_conn_error in scsi_transport_iscsi.c so that iscsi_iser and >>> qla4xxx will have it set when they need it. I will send a patch for this >>> along with a way to have the netlink sock vmio set for all iscsi drivers >>> that need it. >> I already have such a patch, look at: >> http://programming.kicks-ass.net/kernel-patches/vm_deadlock/current/iscsi_vmio.patch >> > > You are drowning me in patches :) I did not see that one. I was still > commenting on this patch :) > > The new patch looks ok. > Oh, I think you need a sock_put to go with netlink lookup (lookup does a hold). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org