From a3344078101ceee46d14a93f7e3a3b91a55d215b Mon Sep 17 00:00:00 2001 From: Guenter Roeck Date: Tue, 24 Sep 2024 08:42:05 -0700 Subject: [PATCH] mm: make SPLIT_PTE_PTLOCKS depend on SMP SPLIT_PTE_PTLOCKS depends on "NR_CPUS >= 4". Unfortunately, that evaluates to true if there is no NR_CPUS configuration option. This results in CONFIG_SPLIT_PTE_PTLOCKS=y for mac_defconfig. This in turn causes the m68k "q800" and "virt" machines to crash in qemu if debugging options are enabled. Making CONFIG_SPLIT_PTE_PTLOCKS dependent on the existence of NR_CPUS does not work since a dependency on the existence of a numeric Kconfig entry always evaluates to false. Example: config HAVE_NO_NR_CPUS def_bool y depends on !NR_CPUS After adding this to a Kconfig file, "make defconfig" includes: $ grep NR_CPUS .config CONFIG_NR_CPUS=64 CONFIG_HAVE_NO_NR_CPUS=y Defining NR_CPUS for m68k does not help either since many architectures define NR_CPUS only for SMP configurations. Make SPLIT_PTE_PTLOCKS depend on SMP instead to solve the problem. Link: https://lkml.kernel.org/r/20240924154205.1491376-1-linux@roeck-us.net Fixes: 394290cba966 ("mm: turn USE_SPLIT_PTE_PTLOCKS / USE_SPLIT_PTE_PTLOCKS into Kconfig options") Signed-off-by: Guenter Roeck Acked-by: David Hildenbrand Reviewed-by: Geert Uytterhoeven Tested-by: Geert Uytterhoeven Signed-off-by: Andrew Morton --- mm/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/Kconfig b/mm/Kconfig index 09aebca1cae3..4c9f5ea13271 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -595,6 +595,7 @@ config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE config SPLIT_PTE_PTLOCKS def_bool y depends on MMU + depends on SMP depends on NR_CPUS >= 4 depends on !ARM || CPU_CACHE_VIPT depends on !PARISC || PA20 -- 2.49.0