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

[SJ Park <sj@kernel.org>]

On Wed, 12 Aug 2026 21:11:43 +0800 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)
> ...
> 
> Let's guard NR_CPUS with SMP instead of using a hardcoded arbitrary CPU
> uplimit here, similar to commit a3344078101c ("mm: make SPLIT_PTE_PTLOCKS
> depend on SMP").
> 
> The initial report from SJ Park was for m68k [1] (m68k is the only arch
> without NR_CPUS in Kconfig), and it will be changed in another patch [2].

Thank you for this patch.  I confirmed this fixes the issue on my setup.

> 
> [1] https://lore.kernel.org/all/anuyFHLUGDjZWY4K@XiangdeMacBook-Pro.local/T/#u
> [2] https://lore.kernel.org/r/20260731094950.1988084-2-ukleinek@kernel.org
> 
> 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: SJ Park <sj@kernel.org>


Thanks,
SJ

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