Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751343AbaGGSZl (ORCPT ); Mon, 7 Jul 2014 14:25:41 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52069 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751321AbaGGSZj (ORCPT ); Mon, 7 Jul 2014 14:25:39 -0400 Date: Mon, 7 Jul 2014 11:30:02 -0700 From: Greg Kroah-Hartman To: Ezequiel Garcia Cc: Thomas Petazzoni , Andrew Lunn , Jason Cooper , Joerg Roedel , Hiroshi.DOYU@nokia.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Laurent Pinchart , Paolo Pisati , Gregory CLEMENT , Sebastian Hesselbarth , Florian Vaussard , linux-arm-kernel@lists.infradead.org Subject: Re: 3.16rc3 multiplatform, Armada 370 and IOMMU: unbootable kernel Message-ID: <20140707183002.GA5947@kroah.com> References: <20140703135146.GA6898@luxor.wired.org> <53B5C61D.2060308@free-electrons.com> <53B5CA26.7050405@free-electrons.com> <1936558.QaAG1bYMuD@avalon> <20140705150308.GA28791@arch.cereza> <20140705205951.GB3678@kroah.com> <20140707105818.GA1101@arch.cereza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140707105818.GA1101@arch.cereza> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 07, 2014 at 07:58:18AM -0300, Ezequiel Garcia wrote: > On 05 Jul 01:59 PM, Greg Kroah-Hartman wrote: > > On Sat, Jul 05, 2014 at 12:03:08PM -0300, Ezequiel Garcia wrote: > > > After following Gregory's stacktrace (also reproduced here): > > > > > > [] (iommu_bus_notifier) from [] (notifier_call_chain+0x64/0x9c) > > > [] (notifier_call_chain) from [] (__blocking_notifier_call_chain+0x40/0x58) > > > [] (__blocking_notifier_call_chain) from [] (blocking_notifier_call_chain+0x14/0x1c) > > > [] (blocking_notifier_call_chain) from [] (device_add+0x424/0x524) > > > [] (device_add) from [] (pci_device_add+0xec/0x110) > > > [] (pci_device_add) from [] (pci_scan_single_device+0xa0/0xac) > > > > > > I added a few printks and found that the problem is that the iommu_bus_notifier is > > > called for the 'pci' bus type, which has a null iommu_ops. > > > > > > On 04 Jul 10:47 AM, Laurent Pinchart wrote: > > > [..] > > > > > > > > We need a quick fix for v3.16, ... > > > > > > Therefore, a quick fix would be to simply check for that: > > > > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > > > index e5555fc..b712cb2 100644 > > > --- a/drivers/iommu/iommu.c > > > +++ b/drivers/iommu/iommu.c > > > @@ -536,6 +536,9 @@ static int iommu_bus_notifier(struct notifier_block *nb, > > > struct iommu_group *group; > > > unsigned long group_action = 0; > > > > > > + if (!ops) > > > + return 0; > > > + > > > /* > > > * ADD/DEL call into iommu driver ops if provided, which may > > > * result in ADD/DEL notifiers to group->notifier > > > > > > This (nasty workaround?) patch makes the problem go away. > > > > > > [..] > > > > > So it also boot well in 3.15 and then failed in 3.16-rc3. I hope it will > > > > > help the developers of the OMAP IOMMU driver to fix it. > > > > > > > > Thank you. I've had a look at the OMAP IOMMU driver changes between v3.15 and > > > > v3.16-rc3, and didn't find at first sight any change that could explain the > > > > crash. > > > > > > > > 286f600 iommu/omap: Fix map protection value handling > > > > 67b779d iommu/omap: Remove comment about supporting single page mappings only > > > > f7129a0 iommu/omap: Fix 'no page for' debug message in flush_iotlb_page() > > > > 5acc97d iommu/omap: Move to_iommu definition from omap-iopgtable.h > > > > 2ac6133 iommu/omap: Remove omap_iommu_domain_has_cap() function > > > > d760e3e iommu/omap: Correct init value of iotlb_entry valid field > > > > > > > > Could you try reverting those changes and retest ? If the problem doesn't > > > > disappear, we'll need to look somewhere else. > > > > > > > > > > I reverted the above commits but nothing changed. I'm far from being an expert, > > > but it sounds odd to have this bus notifier (that got registered for the > > > platform bus type) called by a pci bus type. > > > > Why wouldn't the PCI bus set this up for its devices? Are you > > "assuming" you know the bus type and that's the issue? > > > > Thanks for looking at this. > > I guess I snipped the thread and lost most of the information about the panic. > Here's the original bug report: > > http://www.spinics.net/lists/arm-kernel/msg344059.html > > The problem reported involves enabling OMAP IOMMU driver and not any other IOMMU > driver. Doing some tracing and adding a few prints, we found that > omap_iommu_init() sets a bus notifier for the platform bus type: > > omap_iommu_init -> bus_set_iommu -> iommu_bus_init: > > static void iommu_bus_init(struct bus_type *bus, struct iommu_ops *ops) > { > bus_register_notifier(bus, &iommu_bus_nb); > bus_for_each_dev(bus, NULL, ops, add_iommu_group); > } > > But the iommu bus notifier gets called for the 'pci' bus type, which > has the iommu_ops field NULL (since it hasn't been set for iommu). So this is what needs to be figured out, how is the notifier being called with a PCI device? Who else called iommu_bus_init() for the PCI bus? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/