[PATCH 0/2] vfio/iommufd: Prevent scheduler warnings when unmapping large regions

[Aaron Lewis <aaronlewis@google.com>]

Both the Type1 IOMMU and IOMMUFD can be guilty of not playing nice with
the scheduler during DMA unmapping on large regions (e.g., 256GB). Add
rate-limited calls to cond_resched() to ensure this doesn't happen.

This series was tested using the selftest proposed here:
 - https://lore.kernel.org/kvm/20260701203311.326798-1-aaronlewis@google.com/

And profiled using the bpftrace tooling proposed here:
 - https://lore.kernel.org/kvm/20260630141152.3757722-2-aaronlewis@google.com/

Note that the kernel must be built with preemption disabled and have
LATENCY_WARN enabled in order to trigger the warnings. With those
conditions met, the issue should reproduce as described in the
changelogs. 

Aaron Lewis (2):
  vfio/type1: Periodically try rescheduling when unmapping
  iommufd: Periodically reschedule when unmapping

 drivers/iommu/iommufd/pages.c   | 4 ++++
 drivers/vfio/vfio_iommu_type1.c | 3 +++
 2 files changed, 7 insertions(+)

-- 
2.55.0.141.g00534a21ce-goog