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

[Huacai Chen]

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().

Huacai

>
> > Huacai
> >
> > >
> > > --
> > > Sincerely yours,
> > > Mike.
>
> --
> Sincerely yours,
> Mike.