On Fri, 9 Jan 2009 14:53:14 +0800 "Han, Weidong" <weidong.han@xxxxxxxxx> wrote: > Dirk Hohndel wrote: > > On Thu, 8 Jan 2009 18:05:15 -0800 > > Dirk Hohndel <hohndel@xxxxxxxxxxxxx> wrote: > > > >> On Fri, 9 Jan 2009 08:58:46 +0800 "Han, Weidong" > >> > >> I updated to Linus' latest git (as your description made me wonder > >> if the async stuff might play a role here). I still get an oops - > >> but at a different spot and the system no longer hangs - it partly > >> recovers (but things aren't too well - for example my USB > >> keyboard / mouse don't work anymore). > > > > Spoke too soon. Rebooted and had the same hard lockup again. This > > time I had my camera within reach, so here's the trace: > > > > device_to_iommu+0x33/0x73 > > domain_context_mapping_one+0x37/0x335 > > domain_context_mapping+0x25/0xa7 > > iommu_prepare_identity+0xd7/0xf3 > > intel_iommu_init+0x4e4/0x8f3 > > ? mutex_lock > > ? sysctl_net_init > > ? pci_iommu_init > > pci_iommu_init > > > > I also have stack, code and register values. Let me know if you need > > them. Or I can just post the picture :-) > > > > Again, very latest git tree, VT-d enabled. > > > > /D > > I tried latest git tree, it works for me. Above call trace looks > right. Spent some more time reading the code. Can't quite claim to understand all of it, yet, but I notice that most everywhere else drhd->devices[i] is checked to be != NULL before it is accessed. Why is it safe not to do that in device_to_iommu()? Would the patch below be a valid fix? It stops my system from hanging at boot. But I wonder if there is an assertion that if drhd->ignored is 0 then drhd->devices[0..drhd->device_cnt] is known to be != NULL and therefore this test is just hiding a bug somewhere else... /D Signed-off-by: Dirk Hohndel <hohndel@xxxxxxxxxxxxxxx> --- drivers/pci/intel-iommu.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c index 235fb7a..3dfecb2 100644 --- a/drivers/pci/intel-iommu.c +++ b/drivers/pci/intel-iommu.c @@ -438,7 +438,8 @@ static struct intel_iommu *device_to_iommu(u8 bus, u8 devfn) continue; for (i = 0; i < drhd->devices_cnt; i++) - if (drhd->devices[i]->bus->number == bus && + if (drhd->devices[i] && + drhd->devices[i]->bus->number == bus && drhd->devices[i]->devfn == devfn) return drhd->iommu; -- 1.6.0.6 -- Dirk Hohndel Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
