Re: [PATCH v3 3/5] mm: convert compaction to zone lock wrappers

[Dmitry Ilvokhin <d@ilvokhin.com>]

On Thu, Feb 26, 2026 at 04:45:54PM -0800, SeongJae Park wrote:
> On Thu, 26 Feb 2026 18:26:20 +0000 Dmitry Ilvokhin <d@ilvokhin.com> wrote:
> 
> > Compaction uses compact_lock_irqsave(), which currently operates
> > on a raw spinlock_t pointer so it can be used for both zone->lock
> > and lruvec->lru_lock. Since zone lock operations are now wrapped,
> > compact_lock_irqsave() can no longer directly operate on a
> > spinlock_t when the lock belongs to a zone.
> > 
> > Split the helper into compact_zone_lock_irqsave() and
> > compact_lruvec_lock_irqsave(), duplicating the small amount of
> > shared logic. As there are only two call sites and both statically
> > know the lock type, this avoids introducing additional abstraction
> > or runtime dispatch in the compaction path.
> > 
> > No functional change intended.
> > 
> > Signed-off-by: Dmitry Ilvokhin <d@ilvokhin.com>
> > ---
> >  mm/compaction.c | 33 ++++++++++++++++++++++++---------
> >  1 file changed, 24 insertions(+), 9 deletions(-)
> > 
> > diff --git a/mm/compaction.c b/mm/compaction.c
> > index 47b26187a5df..9f7997e827bd 100644
> > --- a/mm/compaction.c
> > +++ b/mm/compaction.c
> > @@ -503,19 +503,36 @@ static bool test_and_set_skip(struct compact_control *cc, struct page *page)
> >   *
> >   * Always returns true which makes it easier to track lock state in callers.
> >   */
> > -static bool compact_lock_irqsave(spinlock_t *lock, unsigned long *flags,
> > -						struct compact_control *cc)
> > -	__acquires(lock)
> > +static bool compact_zone_lock_irqsave(struct zone *zone,
> > +				      unsigned long *flags,
> > +				      struct compact_control *cc)
> > +__acquires(&zone->lock)
> 
> Nit.  Why don't you keep the indentation?
> 
> My impression based on below output is that mm code prefer indenting
> __acquires().
> 
>     $ git grep __acquires mm
>     mm/compaction.c:__acquires(&zone->_lock)
>     mm/compaction.c:__acquires(&lruvec->lru_lock)
>     mm/khugepaged.c:        __acquires(&khugepaged_mm_lock)
>     mm/userfaultfd.c:       __acquires(ptl1)
>     mm/userfaultfd.c:       __acquires(ptl2)
> 

Thanks for spotting it, will be fixed in v4.

> 
> Thanks,
> SJ
> 
> [...]