x86_32 intermittently fails jdk/javadoc/doclet/testLinkPlatform/TestLinkPlatform.java. I finally managed to reproduce it on one local machine with:

$ CONF=linux-x86-server-fastdebug make run-test TEST=jdk/javadoc/doclet/testLinkPlatform/TestLinkPlatform.java TEST_VM_OPTS="-XX:ActiveProcessorCount=2" JTREG="REPEAT_COUNT=100"

# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/home/shade/shipilev-jdk/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp:1649), pid=2198496, tid=2198505
# fatal error: Overflow during reference processing, can not continue. Please increase MarkStackSizeMax (current value: 4194304) and restart.
#

Host: core11, 11th Gen Intel(R) Core(TM) i5-11500 @ 2.70GHz, 12 cores, 30G, Debian GNU/Linux 11 (bullseye)
Time: Fri Jan 14 14:47:04 2022 CET elapsed time: 9.418540 seconds (0d 0h 0m 9s)

--------------- T H R E A D ---------------

Current thread (0xb4060778): VMThread "VM Thread" [stack: 0xb4180000,0xb4200000] [id=2198505]

Stack: [0xb4180000,0xb4200000], sp=0xb41fea64, free space=506k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0xb735f8] G1ConcurrentMark::weak_refs_work()+0x788
V [libjvm.so+0xb74185] G1ConcurrentMark::remark()+0x135
V [libjvm.so+0xc1af0d] VM_G1PauseConcurrent::doit()+0x1fd
V [libjvm.so+0x1799b20] VM_Operation::evaluate()+0x160
V [libjvm.so+0x17b87fd] VMThread::evaluate_operation(VM_Operation*)+0x11d
V [libjvm.so+0x17b9835] VMThread::inner_execute(VM_Operation*)+0x415
V [libjvm.so+0x17b9969] VMThread::loop()+0xb9
V [libjvm.so+0x17b9a8a] VMThread::run()+0xba
V [libjvm.so+0x16b7c0a] Thread::call_run()+0xfa
V [libjvm.so+0x12fcc0b] thread_native_entry(Thread*)+0x11b
C [libpthread.so.0+0x80b4] start_thread+0xe4