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IDProjectCategoryView StatusLast Update
0015188CentOS-6kernelpublic2018-09-10 02:46
Reportereesau 
PriorityimmediateSeveritymajorReproducibilityalways
Status newResolutionopen 
Product Version6.10 
Target VersionFixed in Version 
Summary0015188: No SMP in kernel-2.6.32-754.3.5.el6.i686 in dual-core Intel Atom N270
DescriptionAfter upgrade to the latest kernel dual-core Intel Atom N270 is recognized as uni-processor. Happened in three different PC's before I noticed this so it's not a flaw in just one CPU. I can't test this on a different 32-bit multi-core CPU, but 64-bit kernel-2.6.32-754.3.5.el6.x86_64 is working fine on several CPU's, including quad-core Intel Atom D510.
Steps To ReproduceBoot with kernel-2.6.32-754.3.5.el6.i686 on Intel Atom N270
Additional Information* /proc/cpuinfo in current kernel-2.6.32-754.3.5.el6.i686

processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 28
model name : Intel(R) Atom(TM) CPU N270 @ 1.60GHz
stepping : 2
microcode : 536
cpu MHz : 1600.000
cache size : 512 KB
physical id : 0
siblings : 1
core id : 0
cpu cores : 1
apicid : 0
initial apicid : 0
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc up arch_perfmon pebs bts aperfmperf eagerfpu pni dtes64 monitor ds_cpl est tm2 ssse3 xtpr pdcm movbe lahf_lm dtherm
bogomips : 3199.92
clflush size : 64
cache_alignment : 64
address sizes : 32 bits physical, 32 bits virtual
power management:

* /proc/cpuinfo in previous kernel-2.6.32-754.2.1.el6.i686:

processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 28
model name : Intel(R) Atom(TM) CPU N270 @ 1.60GHz
stepping : 2
microcode : 536
cpu MHz : 1600.000
cache size : 512 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 1
apicid : 0
initial apicid : 0
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon pebs bts aperfmperf eagerfpu pni dtes64 monitor ds_cpl est tm2 ssse3 xtpr pdcm movbe lahf_lm dtherm
bogomips : 3200.01
clflush size : 64
cache_alignment : 64
address sizes : 32 bits physical, 32 bits virtual
power management:

processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 28
model name : Intel(R) Atom(TM) CPU N270 @ 1.60GHz
stepping : 2
microcode : 536
cpu MHz : 1600.000
cache size : 512 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 1
apicid : 1
initial apicid : 1
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon pebs bts aperfmperf eagerfpu pni dtes64 monitor ds_cpl est tm2 ssse3 xtpr pdcm movbe lahf_lm dtherm
bogomips : 3200.01
clflush size : 64
cache_alignment : 64
address sizes : 32 bits physical, 32 bits virtual
power management:
TagsNo tags attached.

Activities

soto330

soto330

2018-08-28 15:08

reporter   ~0032616

I am seeing the same in Amazon. Interestingly we commonly use R class instances. On our r4.larges after updating to kernel 754.3.5 we will show 1 cpu online and 1 cpu offline

[root@ip-10-0-9-44 centos]# lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 2
On-line CPU(s) list: 0
Off-line CPU(s) list: 1
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 79
Model name: Intel(R) Xeon(R) CPU E5-2686 v4 @ 2.30GHz
Stepping: 1
CPU MHz: 2300.066
BogoMIPS: 4600.13
Hypervisor vendor: Xen
Virtualization type: full
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 46080K
NUMA node0 CPU(s): 0

Yet if we switch to an r3.large this not an issue. I can use 754.3.5 and both cpus will list online. i have tested also with RHEL in amazon and the same issue occurs.



Duplication steps:

1) Spin up the following AMI:

centos: ami-82cfb894
or
rhel: ami-f37b4b99

2) us an R4.large instance type.
3) view lscpu show processor are both running
4) yum update
5) reboot
6) check kernel is running 754.3.5
7) lscpu will show only 1 cpu online

additional note..
8) stop instance
9) change instance type to r3.large
10) confirm kernel
11) lscpu will show both cpus online
mark.lin

mark.lin

2018-09-10 02:46

reporter   ~0032689

I also saw the issue on GCE when using 2 cores vCPU.
However,
It doesn't see such issue on 4 vCPU instance.
It also doesn't see such issue on kernel-2.6.32-754.2.1.el6 RPM for x86_64 in same instance.

Note that I downloaded the script from https://access.redhat.com/sites/default/files/cve-2018-3620--2018-08-14-1255.sh

For 4 vCPU instance, it shows "SMT status: On".
CVE-2018-3620 Detection Script Ver. 1.2

=====
This script is primarily designed to detect CVE-2018-3620 on supported
Red Hat Enterprise Linux systems and kernel packages.
Result may be inaccurate for other RPM based systems.

CPU vendor: Intel
Running kernel: 2.6.32-754.3.5.el6.x86_64
Virtualization: kvm
SMT status: On
Mitigation: Mitigation: PTE Inversion

=====

For 2 vCPU instance,
it shows "SMT status: Off".

=====
CVE-2018-3620 Detection Script Ver. 1.2
This script is primarily designed to detect CVE-2018-3620 on supported
Red Hat Enterprise Linux systems and kernel packages.
Result may be inaccurate for other RPM based systems.

CPU vendor: Intel
Running kernel: 2.6.32-754.3.5.el6.x86_64
Virtualization: kvm
SMT status: Off
Mitigation: Mitigation: PTE Inversion
=====

Reproduce steps:
1. Create a 2 vCPU instance on GCE.
2. Select CentOS 6 image.
3. cat /proc/cpuinfo
4. It shows only 1 CPU
5. cat /sys/devices/system/cpu/cpu1/online
6. It shows "0"

Issue History

Date Modified Username Field Change
2018-08-17 13:08 eesau New Issue
2018-08-28 15:08 soto330 Note Added: 0032616
2018-09-10 02:46 mark.lin Note Added: 0032689