[PATCH] erofs: fix EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS on some UP platforms

[Gao Xiang <xiang@kernel.org>]

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].

[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>
---
Hi Linus,

Could you apply this Kconfig fix directly since I don't have other urgent
patch for 7.2 (so maybe it's unnecessary to have a pull request just for
this..)

Many thank,
Gao Xiang

 fs/erofs/Kconfig | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/erofs/Kconfig b/fs/erofs/Kconfig
index 8ca1767dafb6..2dfc313588d2 100644
--- 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.
-- 
2.47.3