Re: [PATCH v9 4/6] Drivers: hv: Fix huge page handling in memory region traversal

[Nuno Das Neves <nunodasneves@linux.microsoft.com>]

On 12/3/2025 1:40 PM, Stanislav Kinsburskii wrote:
> The previous code assumed that if a region's first page was huge, the
> entire region consisted of huge pages and stored this in a large_pages
> flag. This premise is incorrect not only for movable regions (where
> pages can be split and merged on invalidate callbacks or page faults),
> but even for pinned regions: THPs can be split and merged during
> allocation, so a large, pinned region may contain a mix of huge and
> regular pages.
> 
> This change removes the large_pages flag and replaces region-wide
> assumptions with per-chunk inspection of the actual page size when
> mapping, unmapping, sharing, and unsharing. This makes huge page
> handling correct for mixed-page regions and avoids relying on stale
> metadata that can easily become invalid as memory is remapped.
> 
> Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
> Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
> ---
>  drivers/hv/mshv_regions.c |  219 +++++++++++++++++++++++++++++++++++++++------
>  drivers/hv/mshv_root.h    |    3 -
>  2 files changed, 191 insertions(+), 31 deletions(-)
> 
Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>