Re: [PATCH v5 4/7] mm: Introduce FPB_RESPECT_WRITE for PTE batching infrastructure

[Dev Jain]

On 23/07/25 8:58 pm, Zi Yan wrote:
> On 18 Jul 2025, at 5:02, Dev Jain wrote:
>
> > Patch 6 optimizes mprotect() by batch clearing the ptes, masking in the new
> “Patch 6” might not make sense when reading it in the git log. Something like
> below might be better:

Andrew has fixed that for me :)

> mprotect() will be optimized by batch clearing the ptes, masking in the new
> protections, and batch setting the ptes in an upcoming commit.
>
> No need to repin for this one.
>
> > protections, and batch setting the ptes. Suppose that the first pte
> > of the batch is writable - with the current implementation of
> > folio_pte_batch(), it is not guaranteed that the other ptes in the batch
> > are already writable too, so we may incorrectly end up setting the
> > writable bit on all ptes via modify_prot_commit_ptes().
> >
> > Therefore, introduce FPB_RESPECT_WRITE so that all ptes in the batch
> > are writable or not.
> >
> > Signed-off-by: Dev Jain <dev.jain@xxxxxxx>
> > ---
> >   mm/internal.h | 11 ++++++++---
> >   1 file changed, 8 insertions(+), 3 deletions(-)
> LGTM. Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>

Thanks.

> Best Regards,
> Yan, Zi