From: Qian Cai cai@lca.pw
commit 2d48ea0efb8887ebba3e3720bb5b738aced4e574 upstream.
There are several places traverse RCU-list without holding any lock in intel_iommu_init(). Fix them by acquiring dmar_global_lock.
WARNING: suspicious RCU usage ----------------------------- drivers/iommu/intel-iommu.c:5216 RCU-list traversed in non-reader section!!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1 no locks held by swapper/0/1.
Call Trace: dump_stack+0xa0/0xea lockdep_rcu_suspicious+0x102/0x10b intel_iommu_init+0x947/0xb13 pci_iommu_init+0x26/0x62 do_one_initcall+0xfe/0x500 kernel_init_freeable+0x45a/0x4f8 kernel_init+0x11/0x139 ret_from_fork+0x3a/0x50 DMAR: Intel(R) Virtualization Technology for Directed I/O
Fixes: d8190dc63886 ("iommu/vt-d: Enable DMA remapping after rmrr mapped") Signed-off-by: Qian Cai cai@lca.pw Acked-by: Lu Baolu baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/iommu/intel-iommu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -5024,6 +5024,7 @@ int __init intel_iommu_init(void)
init_iommu_pm_ops();
+ down_read(&dmar_global_lock); for_each_active_iommu(iommu, drhd) { iommu_device_sysfs_add(&iommu->iommu, NULL, intel_iommu_groups, @@ -5031,6 +5032,7 @@ int __init intel_iommu_init(void) iommu_device_set_ops(&iommu->iommu, &intel_iommu_ops); iommu_device_register(&iommu->iommu); } + up_read(&dmar_global_lock);
bus_set_iommu(&pci_bus_type, &intel_iommu_ops); if (si_domain && !hw_pass_through) @@ -5041,7 +5043,6 @@ int __init intel_iommu_init(void) down_read(&dmar_global_lock); if (probe_acpi_namespace_devices()) pr_warn("ACPI name space devices didn't probe correctly\n"); - up_read(&dmar_global_lock);
/* Finally, we enable the DMA remapping hardware. */ for_each_iommu(iommu, drhd) { @@ -5050,6 +5051,8 @@ int __init intel_iommu_init(void)
iommu_disable_protect_mem_regions(iommu); } + up_read(&dmar_global_lock); + pr_info("Intel(R) Virtualization Technology for Directed I/O\n");
intel_iommu_enabled = 1;