+ Paul for comment. Leaving in the rest for him.
On Mon, Jan 09, 2017 at 02:36:33AM +0000, Zheng, Lv wrote: > Hi, > > > From: linux-acpi-ow...@vger.kernel.org > > [mailto:linux-acpi-ow...@vger.kernel.org] On Behalf Of Zheng, > > Lv > > Subject: RE: 174cc7187e6f ACPICA: Tables: Back port > > acpi_get_table_with_size() and > > early_acpi_os_unmap_memory() from Linux kernel > > > > Hi, > > > > > From: linux-acpi-ow...@vger.kernel.org > > > [mailto:linux-acpi-ow...@vger.kernel.org] On Behalf Of > > Borislav > > > Petkov > > > Subject: Re: 174cc7187e6f ACPICA: Tables: Back port > > > acpi_get_table_with_size() and > > > early_acpi_os_unmap_memory() from Linux kernel > > > > > > On Sun, Jan 08, 2017 at 03:20:20AM +0100, Rafael J. Wysocki wrote: > > > > drivers/iommu/amd_iommu_init.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > Index: linux-pm/drivers/iommu/amd_iommu_init.c > > > > =================================================================== > > > > --- linux-pm.orig/drivers/iommu/amd_iommu_init.c > > > > +++ linux-pm/drivers/iommu/amd_iommu_init.c > > > > @@ -2230,7 +2230,7 @@ static int __init early_amd_iommu_init(v > > > > */ > > > > ret = check_ivrs_checksum(ivrs_base); > > > > if (ret) > > > > - return ret; > > > > + goto out; > > > > > > > > amd_iommu_target_ivhd_type = > > > > get_highest_supported_ivhd_type(ivrs_base); > > > > DUMP_printk("Using IVHD type %#x\n", > > > > amd_iommu_target_ivhd_type); > > > > > > Good catch, this one needs to be applied regardless. > > > > > > However, it doesn't fix my issue though. > > > > > > But I think I have it - I went and applied the well-proven debugging > > > technique of sprinkling printks around. Here's what I'm seeing: > > > > > > early_amd_iommu_init() > > > |-> acpi_put_table(ivrs_base); > > > |-> acpi_tb_put_table(table_desc); > > > |-> acpi_tb_invalidate_table(table_desc); > > > |-> acpi_tb_release_table(...) > > > |-> acpi_os_unmap_memory > > > |-> acpi_os_unmap_iomem > > > |-> acpi_os_map_cleanup > > > |-> synchronize_rcu_expedited <-- the kernel/rcu/tree_exp.h version > > > with CONFIG_PREEMPT_RCU=y > > > > > > Now that function goes and sends IPIs, i.e., schedule_work() > > > but this is too early - we haven't even done workqueue_init(). > > > Actually, from looking at the callstack, we do > > > kernel_init_freeable->native_smp_prepare_cpus() and workqueue_init() > > > comes next. > > > > > > And this makes sense because the splat rIP points to __queue_work() but > > > we haven't done that yet. > > > > > > So that acpi_put_table() is happening too early. Looks like AMD IOMMU > > > should not put the table but WTH do I know?! > > > > > > In any case, commenting out: > > > > > > acpi_put_table(ivrs_base); > > > ivrs_base = NULL; > > > > > > and the end of early_amd_iommu_init() makes the box boot again. > > > > So please help to comment out these 2 lines (with descriptions and do not > > delete them). > > Until acpi_os_unmap_memory() is able to handle such an early case. > > IMO, synchronize_rcu_expedited() should be improved: > If rcu_init() isn't called or there is nothing to synchronize, > schedule_work() shouldn't be invoked. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
