3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Samuel Neves <sneves@xxxxxxxxx> [ Upstream commit 4596749339e06dc7a424fc08a15eded850ed78b7 ] Without this fix, /proc/cpuinfo will display an incorrect amount of CPU cores, after bringing them offline and online again, as exemplified below: $ cat /proc/cpuinfo | grep cores cpu cores : 4 cpu cores : 8 cpu cores : 8 cpu cores : 20 cpu cores : 4 cpu cores : 3 cpu cores : 2 cpu cores : 2 This patch fixes this by always zeroing the booted_cores variable upon turning off a logical CPU. Tested-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx> Signed-off-by: Samuel Neves <sneves@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: jgross@xxxxxxxx Cc: luto@xxxxxxxxxx Cc: prarit@xxxxxxxxxx Cc: vkuznets@xxxxxxxxxx Link: http://lkml.kernel.org/r/20180221205036.5244-1-sneves@xxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/smpboot.c | 1 + 1 file changed, 1 insertion(+) --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1290,6 +1290,7 @@ static void remove_siblinginfo(int cpu) cpumask_clear(cpu_core_mask(cpu)); c->phys_proc_id = 0; c->cpu_core_id = 0; + c->booted_cores = 0; cpumask_clear_cpu(cpu, cpu_sibling_setup_mask); }
