Re: [PATCH] mm/gup: don't check page lru flag before draining it

[yangge1116]

在 2024/6/4 下午4:56, Baolin Wang 写道:
> On 2024/6/4 16:09, yangge1116@xxxxxxx wrote:
> > From: yangge <yangge1116@xxxxxxx>
> >
> > If a page is added in pagevec, its ref count increases one, remove
> > the page from pagevec decreases one. Page migration requires the
> > page is not referrened by others except page mapping. Before
> > migrating a page, we should try to drain the page from pagevec in
> > case the page is in it, however, folio_test_lru() is not sufficient
> > to tell whether the page is in pagevec or not, if the page is in
> > pagevec, the migration will fail.
> >
> > Remove the condition and drain lru once to ensure the page is not
> > referrenced by pagevec.
>
> This looks sane to me and seems a simple way to fix.
>
> > Signed-off-by: yangge <yangge1116@xxxxxxx>
> > ---
> >   mm/gup.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/mm/gup.c b/mm/gup.c
> > index ca0f5ce..890dcbc 100644
> > --- a/mm/gup.c
> > +++ b/mm/gup.c
> > @@ -2411,7 +2411,7 @@ static unsigned long 
> > collect_longterm_unpinnable_pages(
> >               continue;
> >           }
> > -        if (!folio_test_lru(folio) && drain_allow) {
> > +        if (drain_allow) {
> >               lru_add_drain_all();
> >               drain_allow = false;
> >           }
>
> You should rebase your code on the latest mm-unstable branch, as 
> collect_longterm_unpinnable_pages() in the upstream has been replaced 
> with collect_longterm_unpinnable_folios().
Ok, thanks