Re: [PATCH] erofs: fix EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS on some UP platforms

[Gao Xiang <xiang@kernel.org>]

Hi Geert,

On Wed, Aug 12, 2026 at 03:34:58PM +0200, Geert Uytterhoeven wrote:
> Hi Gao,
> 
> Thanks for your patch!
> 
> On Wed, 12 Aug 2026 at 15:12, Gao Xiang <xiang@kernel.org> wrote:
> > CONFIG_NR_CPUS doesn't define on some UP platforms (e.g. arm), so this
> > can cause make oldconfig to loop indefinitely when CONFIG_SMP=n:
> >
> >  $ make ARCH=arm allmodconfig
> >  $ sed -i "/CONFIG_SMP=y/d" .config
> >  $ sed -i "/CONFIG_EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS.*/d" .config
> >
> > EROFS LZMA default maximum decompression streams (EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS) [0] (NEW)
> > EROFS LZMA default maximum decompression streams (EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS) [0] (NEW)
> > ...
> 
> This also fixes EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS silently becoming
> zero (and thus breaking decompression completely?) for "automatic"
> configs like "make allmodconfig" or "make olddefconfig" on architectures
> where NR_CPUS depends on SMP (which is most of them).

Yeah, unfortunately..

> 
> >

...

> >
> > Reported-by: SJ Park <sj@kernel.org>
> > Closes: https://lore.kernel.org/r/20260728065447.91511-1-sj@kernel.org
> > Reported-by: Guenter Roeck <groeck7@gmail.com>
> > Closes: https://lore.kernel.org/r/87853c96-cc8f-49e6-81b1-02bfe409e372@roeck-us.net
> > Fixes: c9b47e6b2311 ("erofs: cap LZMA stream pool size")
> > Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> > Signed-off-by: Gao Xiang <xiang@kernel.org>
> 
> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

Thanks!

Thanks,
Gao Xiang

> 
> > --- a/fs/erofs/Kconfig
> > +++ b/fs/erofs/Kconfig
> > @@ -134,7 +134,8 @@ config EROFS_FS_ZIP_LZMA
> >  config EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS
> >         int "EROFS LZMA default maximum decompression streams"
> >         depends on EROFS_FS_ZIP_LZMA
> > -       range 1 NR_CPUS
> > +       range 1 NR_CPUS if SMP
> > +       range 1 1 if !SMP
> >         default 16
> >         help
> >           By default EROFS allocates one LZMA decompression stream per CPU.
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> -- 
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
>