Re: [PATCH v6 5/8] LoongArch: Allow memblock arrays to resize

[Mike Rapoport]

On Fri, Nov 06, 2026 at 10:35:01PM +0800, Huacai Chen wrote:
> On Fri, Nov 6, 2026 at 12:07 AM Mike Rapoport <rppt@xxxxxxxxxx> wrote:
> >
> > On Thu, Nov 05, 2026 at 11:07:01PM +0800, Huacai Chen wrote:
> > > Hi, Mike,
> > >
> > > On Thu, Nov 5, 2026 at 8:57 PM Mike Rapoport <rppt@xxxxxxxxxx> wrote:
> > > >
> > > > On Fri, Oct 30, 2026 at 02:29:52AM +0900, George Guo wrote:
> > > > > From: George Guo <guodongtai@xxxxxxxxxx>
> > > > >
> > > > > LoongArch never calls memblock_allow_resize(), so the reserved region
> > > > > array cannot grow beyond INIT_MEMBLOCK_RESERVED_REGIONS entries
> > > > > (INIT_MEMBLOCK_REGIONS + NR_CPUS).
> > > >
> > > > This might be something to fix independent of KHO.
> > > >
> > > > Huacai,
> > > >
> > > > What's the reason LoongArch never enables memblock resizing and why it
> > > > defines INIT_MEMBLOCK_RESERVED_REGIONS to include NR_CPUS?
> > > At first we didn't define INIT_MEMBLOCK_RESERVED_REGIONS, then we got
> > > boot failures on a 128-cores machine, so define it, and the value is
> > > similar to arm64.
> >
> > AFAIR, arm64 had to reserve some per cpu data before they could enable
> > memblock resizing, so they had to make it static.
> LoongArch is similar, so below 64-cores machine has no problem.
> 
> >
> > > The reason LoongArch never enables memblock resizing is because the mm
> > > code is derived from MIPS, and MIPS never enables it.
> >
> > If that's the only reason, you might want to revisit that :)
> Yes, it seems we need memblock_allow_resize(), but maybe it is better
> to bring back paging_init()? Most other archs call
> memblock_allow_resize() in paging_init().

paging_init() is a historical relict that hugely misnamed everywhere :)

I think platform_init() should be fine.

As far as I can tell, by the time platform_init() calls init_numa_memory(),
all memory reservations that must happen before any memblock allocations
are done.
 
> Huacai

-- 
Sincerely yours,
Mike.