| From foo@baz Sun May 27 17:33:38 CEST 2018 |
| From: Samuel Neves <sneves@dei.uc.pt> |
| Date: Wed, 21 Feb 2018 20:50:36 +0000 |
| Subject: x86/topology: Update the 'cpu cores' field in /proc/cpuinfo correctly across CPU hotplug operations |
| |
| 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(); |
| } |