[~mbaesken] We now observe asserts on AIX, triggered by runtime/Shutdown/ShutdownTest.java:
#
# Internal Error (/priv/jenkins/client-home/workspace/openjdk-jdk-aix_ppc64-dbg/jdk/src/hotspot/os/aix/os_aix.cpp:2393), pid=18416088, tid=2057
# assert(n >= 0) failed: negative CPU time
#

Stack: [0x0000000114230000,0x000000011444c888], sp=0x000000011444b040, free space=2156k
No context given, using current context.
Native frame:
iar: 0x090000000c16ef8c libjvm.so::AixNativeCallstack::print_callstack_for_context(outputStream*, ucontext_t const*, bool, char*, unsigned long)+0x4ec (C++ uses_alloca saves_cr saves_lr stores_bc gpr_saved:18 fixedparms:5 parmsonstk:1)
lr: 0x000000011444a270 (unknown module)::(unknown function)+?
sp: 0x0000000114449fe0 (base - 0x28A8)
rtoc: 0x08001000a045e2f8
|---stackaddr----| |----lrsave------|: <function name>
0x000000011444a3d0 - 0x090000000c16ea24 libjvm.so::os::Aix::platform_print_native_stack(outputStream*, void const*, char*, int, unsigned char*&)+0x24 (C++ uses_alloca saves_lr stores_bc gpr_saved:1 fixedparms:5 parmsonstk:1)
0x000000011444a450 - 0x090000000c16e8d8 libjvm.so::NativeStackPrinter::print_stack(outputStream*, char*, int, unsigned char*&, bool, int)+0x58 (C++ fp_present uses_alloca saves_cr saves_lr stores_bc gpr_saved:6 fixedparms:7 parmsonstk:1)
0x000000011444a560 - 0x090000000c900a58 libjvm.so::VMError::report(outputStream*, bool)+0x23b8 (C++ fp_present uses_alloca saves_cr saves_lr stores_bc gpr_saved:18 fixedparms:2 parmsonstk:1)
0x000000011444b050 - 0x090000000bedc030 libjvm.so::VMError::report_and_die(int, char const*, char const*, char*, Thread*, unsigned char*, void const*, void const*, char const*, int, unsigned long)+0x870 (C++ uses_alloca saves_lr stores_bc gpr_saved:18 fixedparms:8 parmsonstk:1)
0x000000011444b230 - 0x090000000bedb4e0 libjvm.so::report_vm_error(char const*, int, char const*, char const*, ...)+0xa0 (C++ uses_alloca saves_lr stores_bc gpr_saved:5 fixedparms:4 parmsonstk:1)
0x000000011444b2f0 - 0x090000000befbae8 libjvm.so::os::thread_cpu_time(Thread*)+0x68 (C++ uses_alloca saves_lr stores_bc gpr_saved:1 fixedparms:1 parmsonstk:1)
0x000000011444b370 - 0x090000000c13a1e4 libjvm.so::CPUTimeThreadClosure::do_thread(Thread*)+0x24 (C++ uses_alloca saves_lr stores_bc gpr_saved:2 fixedparms:2 parmsonstk:1)
0x000000011444b3f0 - 0x090000000c693878 libjvm.so::G1CollectedHeap::gc_threads_do(ThreadClosure*) const+0x58 (C++ uses_alloca saves_lr stores_bc gpr_saved:3 fixedparms:2 parmsonstk:1)
0x000000011444b480 - 0x090000000c13a15c libjvm.so::CPUTimeUsage::GC::gc_threads()+0x5c (C++ uses_alloca saves_lr stores_bc gpr_saved:1 parmsonstk:1)
0x000000011444b510 - 0x090000000c3b11f8 libjvm.so::G1Analytics::gc_cpu_time_ms() const+0x18 (C++ fp_present uses_alloca saves_lr stores_bc gpr_saved:1 fixedparms:1 parmsonstk:1)
0x000000011444b590 - 0x090000000c3b0efc libjvm.so::G1Policy::record_young_collection_start()+0x5c (C++ fp_present uses_alloca saves_lr stores_bc fpr_saved:1 gpr_saved:6 fixedparms:1 parmsonstk:1)
0x000000011444b650 - 0x090000000c3a3168 libjvm.so::G1YoungCollector::collect()+0x268 (C++ fp_present uses_alloca saves_lr stores_bc gpr_saved:10 fixedparms:1 parmsonstk:1)
0x000000011444bb50 - 0x090000000c39d1f4 libjvm.so::G1CollectedHeap::do_collection_pause_at_safepoint_helper(unsigned long)+0xf4 (C++ uses_alloca saves_lr stores_bc gpr_saved:7 fixedparms:2 parmsonstk:1)
0x000000011444bcf0 - 0x090000000c39d010 libjvm.so::G1CollectedHeap::do_collection_pause_at_safepoint(unsigned long)+0xb0 (C++ uses_alloca saves_lr stores_bc gpr_saved:3 fixedparms:2 parmsonstk:1)
0x000000011444bd80 - 0x090000000c604544 libjvm.so::VM_G1CollectForAllocation::doit()+0xa4 (C++ uses_alloca saves_lr stores_bc gpr_saved:5 fixedparms:1 parmsonstk:1)
0x000000011444be20 - 0x090000000bfdfdc0 libjvm.so::VM_Operation::evaluate()+0x160 (C++ uses_alloca saves_lr stores_bc gpr_saved:6 fixedparms:1 parmsonstk:1)
0x000000011444bfb0 - 0x090000000bfdf784 libjvm.so::VMThread::evaluate_operation(VM_Operation*)+0x184 (C++ fp_present uses_alloca saves_cr saves_lr stores_bc gpr_saved:11 fixedparms:2 parmsonstk:1)
0x000000011444c130 - 0x090000000bfdf08c libjvm.so::VMThread::inner_execute(VM_Operation*)+0x42c (C++ uses_alloca saves_cr saves_lr stores_bc gpr_saved:11 fixedparms:2 parmsonstk:1)
0x000000011444c4e0 - 0x090000000d1d4818 libjvm.so::VMThread::loop()+0xd8 (C++ uses_alloca saves_lr stores_bc gpr_saved:5 fixedparms:1 parmsonstk:1)
0x000000011444c580 - 0x090000000d1d44c8 libjvm.so::VMThread::run()+0x108 (C++ uses_alloca saves_lr stores_bc gpr_saved:5 fixedparms:1 parmsonstk:1)
0x000000011444c650 - 0x090000000bfc7148 libjvm.so::Thread::call_run()+0x128 (C++ uses_alloca saves_lr stores_bc gpr_saved:3 fixedparms:1 parmsonstk:1)
0x000000011444c6e0 - 0x090000000bfc640c libjvm.so::thread_native_entry(Thread*)+0x20c (C++ uses_alloca saves_lr stores_bc gpr_saved:8 fixedparms:1 parmsonstk:1)
0x000000011444c7a0 - 0x090000000056204c libpthreads.a::_pthread_body+0xec (C saves_lr stores_bc gpr_saved:1 fixedparms:1 )
0x000000011444c820 - 0x0000000000000000