From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Jones Subject: Re: velocity driver unmaps incorrect size. Date: Sun, 21 Jun 2009 22:40:44 -0400 Message-ID: <20090622024044.GA3157@redhat.com> References: <20090621173745.GC26093@redhat.com> <20090621.184345.194558005.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: David Miller Return-path: Received: from mx2.redhat.com ([66.187.237.31]:41916 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753369AbZFVCko (ORCPT ); Sun, 21 Jun 2009 22:40:44 -0400 Content-Disposition: inline In-Reply-To: <20090621.184345.194558005.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Sun, Jun 21, 2009 at 06:43:45PM -0700, David Miller wrote: > > ------------[ cut here ]------------ > > WARNING: at lib/dma-debug.c:505 check_unmap+0x1f8/0x4d4() > > Hardware name: > > via-velocity 0000:00:0e.0: DMA-API: device driver frees DMA memory with different size [device address=0x000000001a456242] [map size=90 bytes] [unmap size=1 bytes] > > Ok, bad unmap size is "1". > > > [] ? check_unmap+0x1f8/0x4d4 > > [] warn_slowpath_fmt+0x34/0x48 > > [] check_unmap+0x1f8/0x4d4 > > [] debug_dma_unmap_page+0x71/0x8a > > [] pci_unmap_single+0x74/0x90 [via_velocity] > > [] velocity_tx_srv+0xdd/0x1a0 [via_velocity] > > [] velocity_intr+0x52f/0x5a1 [via_velocity] > > So since this is happening in velocity_tx_srv() it has to be > velocity_free_tx_buf(). It has two cases, one for when > VELOCITY_ZERO_COPY_SUPPORT is defined and one for when that > is not defined. > > There is no way to set that define that I can see in the > tree, so we only need to consider the case where this > macro is not defined: > > static void velocity_free_tx_buf(struct velocity_info *vptr, struct velocity_td_info *tdinfo) > { > ... > if (tdinfo->skb_dma) { > pktlen = (skb->len > ETH_ZLEN ? : ETH_ZLEN); > for (i = 0; i < tdinfo->nskb_dma; i++) { > pci_unmap_single(vptr->pdev, tdinfo->skb_dma[i], pktlen, PCI_DMA_TODEVICE); > tdinfo->skb_dma[i] = 0; > } > } > ... > } > > It seems to me that it's impossible for 'pktlen' to every be > '1' here as the DMA debug code is claiming. It must always > be at least ETH_ZLEN. And that is what is passed in for the > unmap length. > > David is there something wonky in your build or do you have > any local patches applied? Nothing obvious that could explain it. (It's the Fedora 11 kernel, which has no patches to this driver, nor to net/) > Is it possible that for some reason > your build is forcing VELOCITY_ZERO_COPY_SUPPORT to be defined > for some reason? Memory corruption maybe? It's especially odd in that it only happens once during boot, and never happens again. This is my firewall/router, so there's more packets going through that box than any other I have. btw, given the zerocopy stuff has been disabled for so long, is it worth keeping it ? Dave