The following commit has been merged into the x86/cpu branch of tip: Commit-ID: 1edae1ae62589f28d00da186465a003e2a7f9c6c Gitweb: https://git.kernel.org/tip/1edae1ae62589f28d00da186465a003e2a7f9c6c Author: Scott Wood <swood@xxxxxxxxxx> AuthorDate: Sat, 12 Oct 2019 02:00:54 -05:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Thu, 17 Oct 2019 18:04:51 +02:00 x86/Kconfig: Enforce limit of 512 CPUs with MAXSMP and no CPUMASK_OFFSTACK The help text of NR_CPUS says that the maximum number of CPUs supported without CPUMASK_OFFSTACK is 512. However, NR_CPUS_RANGE_END allows this limit to be bypassed by MAXSMP even if CPUMASK_OFFSTACK is not set. This scenario can currently only happen in the RT tree, since it has "select CPUMASK_OFFSTACK if !PREEMPT_RT_FULL" in MAXSMP. However, even if we ignore the RT tree, checking for MAXSMP in addition to CPUMASK_OFFSTACK is redundant. Signed-off-by: Scott Wood <swood@xxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Mike Travis <mike.travis@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: x86-ml <x86@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20191012070054.28657-1-swood@xxxxxxxxxx --- arch/x86/Kconfig | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 91c22ee..896f840 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1000,8 +1000,8 @@ config NR_CPUS_RANGE_END config NR_CPUS_RANGE_END int depends on X86_64 - default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK) - default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK) + default 8192 if SMP && CPUMASK_OFFSTACK + default 512 if SMP && !CPUMASK_OFFSTACK default 1 if !SMP config NR_CPUS_DEFAULT
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