Database/Kernel, userspace & hypervisor
Linux kernel (drivers/iommu/arm/arm-smmu-v3): A process using SVA that unmaps memory drives a flood of SMMU range
Impact
A process using SVA that unmaps memory drives a flood of SMMU range invalidations, spinning a CPU in the command queue long enough to trip the soft-lockup watchdog - 26 seconds in the upstream report on a 244-CPU box. One tenant's munmap becomes a multi-second stall of the shared SMMU command queue, which stalls invalidation and DMA setup for every other device and tenant behind that SMMU.
Who can reach it
An unprivileged process using SVA/PASID on an arm64 host with SMMUv3 - the configuration on Grace-based GPU nodes. The trigger is an ordinary large munmap in a process that holds an SVA binding: no host root, no crafted request, no race to win. x86 hosts are unaffected.
What to do
The record lists no fixed release; boot a kernel carrying the stable fix commits below. Interim control: do not enable SVA/PASID for tenant workloads on unpatched arm64 SMMUv3 nodes.
References
This entry is curated: imported from vendor advisories with machine assistance, not yet individually verified. Confirm against your vendor's advisory before acting, and report anything wrong.