On Sat, Jun 17, 2023 at 08:48:38PM +0100, Lorenzo Stoakes wrote:
> On Tue, Jun 13, 2023 at 05:53:44PM -0400, Peter Xu wrote:
> > The only path that doesn't use generic "**pages" handling is the gate vma.
> > Make it use the same path, meanwhile tune the next_page label upper to
> > cover "**pages" handling. This prepares for THP handling for "**pages".
> >
> > Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
> > ---
> > mm/gup.c | 7 +++----
> > 1 file changed, 3 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/gup.c b/mm/gup.c
> > index 8d59ae4554e7..a2d1b3c4b104 100644
> > --- a/mm/gup.c
> > +++ b/mm/gup.c
> > @@ -1135,7 +1135,7 @@ static long __get_user_pages(struct mm_struct *mm,
> > if (!vma && in_gate_area(mm, start)) {
> > ret = get_gate_page(mm, start & PAGE_MASK,
> > gup_flags, &vma,
> > - pages ? &pages[i] : NULL);
> > + pages ? &page : NULL);
>
> Good spot... ugh that we handled this differently.
>
> > if (ret)
> > goto out;
> > ctx.page_mask = 0;
>
> We can drop this line now right? As the new next_page block will duplicate
> this.
OK I can see why you left this in given the last patch in the series :)
Please disregard.
>
> > @@ -1205,19 +1205,18 @@ static long __get_user_pages(struct mm_struct *mm,
> > ret = PTR_ERR(page);
> > goto out;
> > }
> > -
> > - goto next_page;
>
> This is neat, we've already checked if pages != NULL so the if (pages)
> block at the new next_page label will not be run.
>
> > } else if (IS_ERR(page)) {
> > ret = PTR_ERR(page);
> > goto out;
> > }
> > +next_page:
> > if (pages) {
> > pages[i] = page;
> > flush_anon_page(vma, page, start);
> > flush_dcache_page(page);
>
> I guess there's no harm that we now flush here, though it seems to me to be
> superfluous, it's not a big deal I don't think.
>
> > ctx.page_mask = 0;
> > }
> > -next_page:
> > +
> > page_increm = 1 + (~(start >> PAGE_SHIFT) & ctx.page_mask);
> > if (page_increm > nr_pages)
> > page_increm = nr_pages;
> > --
> > 2.40.1
> >
>
> Other than that, LGTM,
>
> Reviewed-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
