[PATCH v2 00/19] mm: Support huge pfnmaps

[Jiaqi Yan]

On Wed, Sep 4, 2024 at 8:52 AM Jason Gunthorpe <jgg at nvidia.com> wrote:
>
> On Thu, Aug 29, 2024 at 12:21:39PM -0700, Jiaqi Yan wrote:
>
> > I think we still want to attempt to SIGBUS userspace, regardless of
> > doing unmap_mapping_range or not.
>
> IMHO we need to eliminate this path if we actually want to keep things
> mapped.
>
> There is no way to generate the SIGBUS without poking a 4k hole in the
> 1G page, as only that 4k should get SIGBUS, every other byte of the 1G
> is clean.

Ah, sorry I wasn't clear. The SIGBUS will be only for poisoned PFN;
clean PFNs under the same PUD/PMD for sure don't need any SIGBUS,
which is the whole purpose of not unmapping.

>
> Jason