Dave Lloyd <dave at davelloyd.com> writes: > On Tue, May 14, 2013 at 5:01 PM, Eric W. Biederman > <ebiederm at xmission.com> wrote: > >> >> Yes this does seem to be all over the place, and memory corruption >> probably caused by ongoing-dma seems like a reasonable hypothesis. > > Thank goodness it's not just me! :-) It is a classic issue, although I suspect something is unique in your setup because it has (to my knowledge) not been a widespread problem for years. >> The easy first thing to try is to remove all of your kernel modules >> before you reboot with kexec. Not infrequently the module remove path >> is better tested than the device shutdown path. > > I'm trying this now. In one panic, the pte referenced was > 0x100010000000000 which sure looks a whole like someone wrote his > registers in there. It certainly doesn't look like a valid pte. > > So far, unloading pata_acpi and pata_amd seem to have eliminated the > ACPI exception messages. I believe that this resets the device > properly. Unfortunately, it looks like lots of drivers don't implement > the pci_driver->shutdown call, so it would make sense that this is a > relatively widespread problem. Most devices don't leave dma setup if you reboot, and even more the generic pci clears the bus master DMA bit which shuts down a lot more dma. So the actual lack of a shutdown method is not as much of an issue as it might appear. Eric
