* Jason Gunthorpe <jgg@xxxxxxxxxx> [220330 14:21]: > On Wed, Mar 30, 2022 at 05:00:39PM +0300, Tony Lindgren wrote: > > Hi, > > > > * Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> [700101 02:00]: > > > The is_attach_deferred iommu_ops callback is a device op. The domain > > > argument is unnecessary and never used. Remove it to make code clean. > > > > Looks like this causes a regression for at least drivers/iommu/omap-iommu.c. > > > > To me it seems the issue is there is no is_attach_deferred implemented, so > > we get a NULL pointer dereference at virtual address 00000008: > > > > __iommu_probe_device from probe_iommu_group+0x2c/0x38 > > probe_iommu_group from bus_for_each_dev+0x74/0xbc > > bus_for_each_dev from bus_iommu_probe+0x34/0x2e8 > > bus_iommu_probe from bus_set_iommu+0x80/0xc8 > > bus_set_iommu from omap_iommu_init+0x88/0xcc > > omap_iommu_init from do_one_initcall+0x44/0x24c > > > > Any ideas for a fix? > > > > It would be good to fix this quickly so we don't end up with a broken > > v5.18-rc1.. > > > > For reference, this is mainline commit 41bb23e70b50 ("iommu: Remove unused > > argument in is_attach_deferred"). > > Are you confident in the bisection? I don't see how that commit could > NULL deref.. Oops sorry you're right, the breaking commit is a different patch, it's 3f6634d997db ("iommu: Use right way to retrieve iommu_ops") instead. I must have picked the wrong commit while testing. > Can you find the code that is the NULL deref? I can debug a bit more tomorrow. Regards, Tony