Red Hat Bugzilla – Bug 1460976
Certain sequence of CPU online/offlineresults in hard crash on 2 core x 2 thread i7 CPU
Last modified: 2017-12-12 05:38:21 EST
Description of problem:
Discovered this by accident on a 2 core x 2 thread i7 CPU:
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
On-line CPU(s) list: 0-3
Thread(s) per core: 2
Core(s) per socket: 2
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model name: Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz
CPU MHz: 499.877
CPU max MHz: 3400.0000
CPU min MHz: 400.0000
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 4096K
NUMA node0 CPU(s): 0-3
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch epb intel_pt tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx rdseed adx smap clflushopt xsaveopt xsavec xgetbv1 xsaves dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_epp
Version-Release number of selected component (if applicable):
Occurred 2 times in 2 attempts.
Steps to Reproduce:
1. Offline cpu1 (Core 0, thread 1)
# echo 0 > /sys/devices/system/cpu/cpu1/online
2. Online cpu1 again
# echo 1 > /sys/devices/system/cpu/cpu1/online
3. Offline cpu3 (Core 1, thread 1)
# echo 0 > /sys/devices/system/cpu/cpu3/online
System freezes hard. No kdump generated.
End up with CPUs 0,1,2 online, CPU 3 offline.
Toggling cpu3 then cpu 1 doesn't seem to have the same effect.
Created attachment 1287200 [details]
/proc/cpuinfo contents for reference
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