linux-kernel - [PATCH] mm: Make SPLIT_PTE_PTLOCKS depend on the existence of NR

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Message-ID: <20240923142533.1197982-1-linux@roeck-us.net>
Date: Mon, 23 Sep 2024 07:25:33 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Guenter Roeck <linux@...ck-us.net>,
	David Hildenbrand <david@...hat.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH] mm: Make SPLIT_PTE_PTLOCKS depend on the existence of NR_CPUS

SPLIT_PTE_PTLOCKS already depends on "NR_CPUS >= 4", but that evaluates
to true if there is no NR_CPUS configuration option (such as for m68k).
This results in CONFIG_SPLIT_PTE_PTLOCKS=y for mac_defconfig.
This in turn causes the m68k "q800" machine to crash in qemu.

Adding an explicit dependency on the existence of NR_CPUS fixes the
problem.

Fixes: 394290cba966 ("mm: turn USE_SPLIT_PTE_PTLOCKS / USE_SPLIT_PTE_PTLOCKS into Kconfig options")
Cc: David Hildenbrand <david@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 mm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index 09aebca1cae3..20fe60389cf5 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -595,7 +595,7 @@ config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
 config SPLIT_PTE_PTLOCKS
 	def_bool y
 	depends on MMU
-	depends on NR_CPUS >= 4
+	depends on NR_CPUS && NR_CPUS >= 4
 	depends on !ARM || CPU_CACHE_VIPT
 	depends on !PARISC || PA20
 	depends on !SPARC32
-- 
2.45.2