Re: [PATCH 0/3] nouveau/vmm: fix switching between small and large PTEs (series v2)

[Mary Guillemard <mary@mary.zone>]

On Wed, Feb 04, 2026 at 01:00:04PM +1000, Dave Airlie wrote:
> [This is a repost with a fix for a bug noticed in patch 2 from yesterday.]
> 
> The nouveau page table has dual page tables with special states for
> tracking small vs large pages at the bottom level. However the current
> code isn't designed with the higher level large page support in mind.
> 
> The nouveau_uvmm/gpuvm code can cause unrefs to get delayed, so things
> like ref SPT, map SPT, unmap SPT, ref LPT, map LPT, unref SPT can happen.
> 
> unrefs can end up quite delayed and it shouldn't matter as unref should
> just affect reference counts.
> 
> However at least the SPT unref path was overwriting the LPT value when
> all SPT were unreffed even if an LPT was referenced in between.
> 
> This series refactors the code to use a union, then increases the size
> as I think even with the current code there was enough ref counts for SPTE.
> The last patch adds LPTE tracking.
> 
> Dave.
>

I extensively tested this today (on GA107 and AD107) with compression
reenabled on mesa side, everything is working as expected and the MMU
faults are gone.

Reviewed-by: Mary Guillemard <mary@mary.zone>
Tested-by: Mary Guillemard <mary@mary.zone>

Regards,
Mary