Re: [RFC PATCH 00/16] 1GB THP support on x86_64

[Jason Gunthorpe]

On Wed, Sep 02, 2020 at 02:45:37PM -0400, Zi Yan wrote:

> > Surprised this doesn't touch mm/pagewalk.c ?
> 
> 1GB PUD page support is present for DAX purpose, so the code is there
> in mm/pagewalk.c already. I only needed to supply ops->pud_entry when using
> the functions in mm/pagewalk.c. :)

Yes, but doesn't this change what is possible under the mmap_sem
without the page table locks?

ie I would expect some thing like pmd_trans_unstable() to be required
as well for lockless walkers. (and I don't think the pmd code is 100%
right either)

Jason