On Wed, Apr 07, 2021 at 05:49:14PM +0200, Vlastimil Babka wrote:
> On 4/1/21 11:24 PM, Sergei Trofimovich wrote:
> > Very minor optimization.
>
> I'm not entirely sure about accuracy of "only for tracked pages". Missing
> page_ext is something I'm not even sure how possible it is in practice, probably
> just an error condition (failed to be allocated?). Or did you observe this in
> practice? But anyway, the change is not wrong.
Never saw missing 'page_ext' in practice (I also did not check for
it explicitly). I agree "optimization" is misleading. "cleanup"
might be a better wording.
> > CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > CC: linux-mm@xxxxxxxxx
> > Signed-off-by: Sergei Trofimovich <slyfox@xxxxxxxxxx>
>
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
>
> > ---
> > mm/page_owner.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/page_owner.c b/mm/page_owner.c
> > index 63e4ecaba97b..7147fd34a948 100644
> > --- a/mm/page_owner.c
> > +++ b/mm/page_owner.c
> > @@ -140,14 +140,14 @@ void __reset_page_owner(struct page *page, unsigned int order)
> > {
> > int i;
> > struct page_ext *page_ext;
> > - depot_stack_handle_t handle = 0;
> > + depot_stack_handle_t handle;
> > struct page_owner *page_owner;
> >
> > - handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
> > -
> > page_ext = lookup_page_ext(page);
> > if (unlikely(!page_ext))
> > return;
> > +
> > + handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
> > for (i = 0; i < (1 << order); i++) {
> > __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
> > page_owner = get_page_owner(page_ext);
> >
>
--
Sergei
