Did not use to happen 3 weeks ago. Right before systemd's fschk kicks in.
Relevant dmesg bits:
[ 0.021970] DMAR: Host address width 39 [ 0.021971] DMAR: DRHD base: 0x000000fed90000 flags: 0x1 [ 0.021976] DMAR: dmar0: reg_base_addr fed90000 ver 1:0 cap d2008c20660462 ecap f010da [ 0.021977] DMAR: RMRR base: 0x000000dd82b000 end: 0x000000dd837fff [ 0.021978] DMAR-IR: IOAPIC id 8 under DRHD base 0xfed90000 IOMMU 0 [ 0.021979] DMAR-IR: HPET id 0 under DRHD base 0xfed90000 [ 0.021980] DMAR-IR: Queued invalidation will be enabled to support x2apic and Intr-remapping. [ 0.022079] DMAR: DRHD: handling fault status reg 2 [ 0.022084] DMAR: [DMA Read] Request device [01:00.0] fault addr c0001000 [fault reason 06] PTE Read access is not set [ 0.022151] DMAR-IR: Enabled IRQ remapping in x2apic mode [ 0.022151] x2apic enabled [ 0.022155] Switched APIC routing to cluster x2apic.
CPU is an i5-4670, and vt-d is enabled. iGPU is disabled.