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Commit 649c6653 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

x86: improve UP kernel when CPU-hotplug and SMP is enabled 



num_possible_cpus() can be > 1 when disabled CPUs have been accounted.

Disabled CPUs are not in the cpu_present_map, so we can use
num_present_cpus() as a safe indicator to switch to UP alternatives.

Reported-by: default avatarChuck Ebbert <cebbert@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 8a541665

arch/x86/kernel/alternative.c

+1 −1
Original line number Diff line number Diff line
@@ -444,7 +444,7 @@ void __init alternative_instructions(void) 
					    _text, _etext);



		/* Only switch to UP mode if we don't immediately boot others */

		if (num_possible_cpus() == 1 || setup_max_cpus <= 1)

		if (num_present_cpus() == 1 || setup_max_cpus <= 1)

			alternatives_smp_switch(0);

	}

#endif