Re: [PATCH v3 3/4] mm: hugetlb: change to return bool for isolate_hugetlb()

[Baolin Wang]

On 2/16/2023 4:25 AM, SeongJae Park wrote:
> On Wed, 15 Feb 2023 18:39:36 +0800 Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> wrote:
>
> > Now the isolate_hugetlb() only returns 0 or -EBUSY, and most users did not
> > care about the negative value, thus we can convert the isolate_hugetlb()
> > to return a boolean value to make code more clear when checking the
> > hugetlb isolation state. Moreover converts 2 users which will consider
> > the negative value returned by isolate_hugetlb().
> >
> > No functional changes intended.
> >
> > Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> > Acked-by: David Hildenbrand <david@xxxxxxxxxx>
> > ---
> [...]
> >   include/linux/hugetlb.h |  6 +++---
> >   mm/hugetlb.c            | 13 ++++++++-----
> >   mm/memory-failure.c     |  2 +-
> >   mm/mempolicy.c          |  2 +-
> >   mm/migrate.c            |  7 +++----
> >   5 files changed, 16 insertions(+), 14 deletions(-)
> [...]
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 3a01a9dbf445..16513cd23d5d 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -2925,13 +2925,16 @@ static int alloc_and_dissolve_hugetlb_folio(struct hstate *h,
> >   		 */
> >   		goto free_new;
> >   	} else if (folio_ref_count(old_folio)) {
> > +		bool isolated;
> > +
> >   		/*
> >   		 * Someone has grabbed the folio, try to isolate it here.
> >   		 * Fail with -EBUSY if not possible.
> >   		 */
> >   		spin_unlock_irq(&hugetlb_lock);
> > -		ret = isolate_hugetlb(old_folio, list);
> > +		isolated = isolate_hugetlb(old_folio, list);
> >   		spin_lock_irq(&hugetlb_lock);
> > +		ret = isolated ? 0 : -EBUSY;
> >   		goto free_new;
>
> Nit.  I'd personally prefer to set 'ret' before entering this critical section
> to keep the section short, but this would be just a mean comment that wouldn't
> worth request respin.

Yes, good catch. And I see Andrew has helped to do this (Thanks Andrew).

Thanks for reviewing.