On Sat, Jul 05, 2014 at 12:03:08PM -0300, Ezequiel Garcia wrote: > After following Gregory's stacktrace (also reproduced here): > > [<c02451f8>] (iommu_bus_notifier) from [<c00512e8>] > (notifier_call_chain+0x64/0x9c) > [<c00512e8>] (notifier_call_chain) from [<c00514cc>] > (__blocking_notifier_call_chain+0x40/0x58) > [<c00514cc>] (__blocking_notifier_call_chain) from [<c00514f8>] > (blocking_notifier_call_chain+0x14/0x1c) > [<c00514f8>] (blocking_notifier_call_chain) from [<c01d225c>] > (device_add+0x424/0x524) > [<c01d225c>] (device_add) from [<c0186d90>] (pci_device_add+0xec/0x110) > [<c0186d90>] (pci_device_add) from [<c0186e54>] > (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? I see the a number of different places this is being initialized for the pci bus. Ah, look at drivers/iommu/fsl_pamu_domain.c, odds are, it shouldn't be doing that logic in the pamu_domain_init() code, using the same bus ops for different bus types, that's ripe for major problems... thanks, greg k-h _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
