4.9-stable review patch. If anyone has any objections, please let me know.
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From: Samuel Neves sneves@dei.uc.pt
[ 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@cn.fujitsu.com Signed-off-by: Samuel Neves sneves@dei.uc.pt Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: jgross@suse.com Cc: luto@kernel.org Cc: prarit@redhat.com Cc: vkuznets@redhat.com Link: http://lkml.kernel.org/r/20180221205036.5244-1-sneves@dei.uc.pt Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/smpboot.c | 1 + 1 file changed, 1 insertion(+)
--- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1497,6 +1497,7 @@ static void remove_siblinginfo(int cpu) cpumask_clear(topology_core_cpumask(cpu)); c->phys_proc_id = 0; c->cpu_core_id = 0; + c->booted_cores = 0; cpumask_clear_cpu(cpu, cpu_sibling_setup_mask); recompute_smt_state(); }