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

[Huacai Chen]

On Sun, Nov 8, 2026 at 4:14 PM Mike Rapoport <rppt@xxxxxxxxxx> wrote:
>
> 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.
If paging_init() is unnecessary, then arch_mem_init() is better than
platform_init(), at least the name is better.

Huacai

>
> 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.