[PATCH] drm/shmem-helper: Don't remove the offset in vm_area_struct pgoff

[Neil Roberts]

Daniel Vetter <daniel at ffwll.ch> writes:

> Yeah plus Cc: stable for backporting and I think an igt or similar for
> panfrost to check this works correctly would be pretty good too. Since
> if it took us over 1 year to notice this bug it's pretty clear that
> normal testing doesn't catch this. So very likely we'll break this
> again.

I made the IGT test below which seems to reproduce the bug. However, the
kernel patch doesn’t fix it, so maybe there is something more subtle
going on.

https://gitlab.freedesktop.org/nroberts/igt-gpu-tools/-/commits/panfrost-purgemap/

Regards,
- Neil