Re: [PATCH] mm/huge_memory: let special huge VMAs bypass the THP policy check

[Jason Gunthorpe]

On Wed, Aug 05, 2026 at 07:55:40AM +0200, Cédric Le Goater wrote:

> The result: each 256 GB BAR is mapped at 4 KiB granularity -- 67 million
> page faults per GPU instead of a few thousand PMD/PUD faults. On hosts
> with 8 GPUs (2 TB of BAR space), this causes VM boot times to degrade
> severely, with 99.98% of CPU time spent in the VFIO BAR mapping path.

Broadly upstream we expect people to use iommufd and dmabuf for these
configurations to avoid all this nonsense overhead. :\

Jason