From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: ixgbe NULLL pointer dereference on OOM condition, 2.6.31.7 Date: Tue, 12 Jan 2010 21:28:18 -0800 Message-ID: <4B4D59F2.4080909@candelatech.com> References: <4B424825.2070608@candelatech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: NetDev To: "Brandeburg, Jesse" Return-path: Received: from mail.candelatech.com ([208.74.158.172]:48488 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751777Ab0AMF2V (ORCPT ); Wed, 13 Jan 2010 00:28:21 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 01/12/2010 06:13 PM, Brandeburg, Jesse wrote: > On Mon, 4 Jan 2010, Ben Greear wrote: > >> This is on a hacked 2.6.31.7 kernel. I'm testing an application that creates >> 30,000+ TCP connections (to self). The system is 64-bit with 12GB of RAM, but >> it can still run out of usable RAM (say, when I start another 10k connections >> to bring it up to 40k). >> >> It looks like something in ixgbe isn't properly checking for inability >> to allocate (or to have previously allocated) an skb, or perhaps some other >> chunk of memory: >> >> [root@ct503-10G-09 ~]# BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8 >> IP: [] ixgbe_clean_rx_irq+0xe4/0x522 [ixgbe] > > Hi Ben, thanks for the report, is there a chance you can run gdb on your > kernel (was it compiled with debug info?) and check the > gdb> l *(ixgbe_clean_rx_irq+0xe4) > > Sorry I'm so slow to respond. > > it seems there are some unwind problems after the recent round of patches > to remove skb_dma_map/unmap, but those were only introduced in 2.6.33-rc1. > Before that we weren't aware of any failure path issues. > > I'm building a kernel now to see if I can figure out the offset where > you're showing the problem. I don't have symbols in mine currently..but I can re-compile tomorrow and attempt to reproduce it. I have a few patches from Intel developers in the ixgbe driver, so it's not stock anymore. I don't expect you to want to download my tree, but just in case you do, it's at: git clone git://dmz1.candelatech.com/linux-2.6.dev.31.y I was using the 64-bit config file found in the /configs dir Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com