[PATCH v8 1/2] kho: fix deferred initialization of scratch areas

[Mike Rapoport]

On Mon, Apr 20, 2026 at 03:11:03PM +0200, Michał Cłapiński wrote:
> On Thu, Apr 16, 2026 at 6:13 PM Mike Rapoport <rppt at kernel.org> wrote:
> >
> > On Thu, Apr 16, 2026 at 05:06:10PM +0200, Michał Cłapiński wrote:
> > > On Thu, Apr 16, 2026 at 4:45 PM Mike Rapoport <rppt at kernel.org> wrote:
> > > >
> > > > Hi Michal,
> > > >
> > > > On Thu, Apr 16, 2026 at 01:06:53PM +0200, Michal Clapinski wrote:
> > > > > @@ -2262,6 +2253,12 @@ static void __init memmap_init_reserved_range(phys_addr_t start,
> > > > >                * access it yet.
> > > > >                */
> > > > >               __SetPageReserved(page);
> > > > > +
> > > > > +#ifdef CONFIG_MEMBLOCK_KHO_SCRATCH
> > > >
> > > > No need for #ifdef here, there's a stub returning false for
> > > > CONFIG_MEMBLOCK_KHO_SCRATCH=n case.
> > >
> > > In all 3 places the #ifdef is there because MIGRATE_CMA might be
> > > undefined. I already broke mm-new branch in the past because of that.
> >
> > Hmm, that hurts :/
> >
> > The best I can think of is to add a static inline in memblock.h and ifdefs
> > around it.
> 
> Sorry, I don't understand what you mean. What would that static inline contain?

Something like this:

#ifdef CONFIG_MEMBLOCK_KHO_SCRATCH
static inline enum migratetype kho_scratch_migratetype(unsigned long pfn,
						       enum migratetype mt)
{
	if (memblock_is_kho_scratch_memory(PFN_PHYS(pfn)))
		return MIGRATE_CMA
	return mt;
}
#else
static inline enum migratetype kho_scratch_migratetype(unsigned long pfn,
						       enum migratetype mt)
{
	return mt;
}
#endif

Can't say I'm happy about the name, but could not think of something
better.

> > > > > +             if (memblock_is_kho_scratch_memory(PFN_PHYS(pfn)) &&
> > > > > +                 pageblock_aligned(pfn))
> > > > > +                     init_pageblock_migratetype(page, MIGRATE_CMA, false);
> > > > > +#endif
> > > > >       }
> > > > >  }
> >
> > --
> > Sincerely yours,
> > Mike.

-- 
Sincerely yours,
Mike.