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

[Jason Gunthorpe <jgg@nvidia.com>]

On Tue, Jul 14, 2026 at 09:03:01PM +0000, Aaron Lewis wrote:
> 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/

Given this is the same issue on both in the some place, I wonder if it
is better to try to get this series done:

https://lore.kernel.org/linux-iommu/20260603151804.1963871-1-guanghuifeng@linux.alibaba.com/

And put the cond sched inside the iova_to_phys_length() ?

It would be fine to do things in steps, like add the
iova_to_phys_length() that just does the loops iommufd and vfio have
today with the additional cond sched inside which isn't such a big
task.

Jason