After JDK-8359104 where getting RSS was improved, we still see sporadic failures of the test gc/TestAlwaysPreTouchBehavior.java#<gcname> , for different gcs.
E.g. gc/TestAlwaysPreTouchBehavior.java#Epsilon (with -Xlog:os=debug added for more output) :

----------System.out:(36/5251)----------
[0.004s][debug][os] Initial active processor count set to 16
[0.004s][info ][os] Use of CLOCK_MONOTONIC is supported
[0.004s][info ][os] Use of pthread_condattr_setclock is supported
[0.004s][info ][os] Relative timed-wait using pthread_cond_timedwait is associated with CLOCK_MONOTONIC
[0.004s][info ][os] HotSpot is running with glibc 2.34, NPTL 2.34
[0.004s][info ][os] Glibc stack size guard page adjustment is not needed
[0.004s][info ][os] SafePoint Polling address, bad (protected) page:0x00007fa723fad000, good (unprotected) page:0x00007fa723fae000
[0.008s][info ][os] attempting shared library load of /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjava.so
[0.009s][info ][os] shared library load of /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjava.so was successful
[0.211s][info ][os] Initialized VM with process ID 248969
[0.260s][info ][os] attempting shared library load of /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libsimdsort.so
[0.260s][info ][os] shared library load of /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libsimdsort.so was successful
[0.289s][debug][os] Symbol JNI_OnLoad_nio not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/bin/java: undefined symbol: JNI_OnLoad_nio
[0.290s][info ][os] attempting shared library load of /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libnio.so
[0.290s][info ][os] shared library load of /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libnio.so was successful
[0.290s][debug][os] Symbol Java_sun_nio_fs_UnixNativeDispatcher_init not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjava.so: undefined symbol: Java_sun_nio_fs_UnixNativeDispatcher_init
[0.290s][debug][os] Symbol Java_sun_nio_fs_UnixNativeDispatcher_getcwd not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjava.so: undefined symbol: Java_sun_nio_fs_UnixNativeDispatcher_getcwd
[0.291s][debug][os] Symbol Java_sun_nio_fs_UnixNativeDispatcher_stat0 not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjava.so: undefined symbol: Java_sun_nio_fs_UnixNativeDispatcher_stat0
[0.297s][debug][os] Symbol JNI_OnLoad_zip not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/bin/java: undefined symbol: JNI_OnLoad_zip
[0.297s][info ][os] attempting shared library load of /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libzip.so
[0.297s][info ][os] shared library load of /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libzip.so was successful
[0.297s][debug][os] Symbol Java_java_util_zip_Inflater_initIDs not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjava.so: undefined symbol: Java_java_util_zip_Inflater_initIDs
[0.297s][debug][os] Symbol Java_java_util_zip_Inflater_init not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjava.so: undefined symbol: Java_java_util_zip_Inflater_init
[0.298s][debug][os] Symbol Java_java_util_zip_Inflater_inflateBytesBytes not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjava.so: undefined symbol: Java_java_util_zip_Inflater_inflateBytesBytes
[0.298s][debug][os] Symbol Java_java_util_zip_Inflater_reset not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjava.so: undefined symbol: Java_java_util_zip_Inflater_reset
[0.299s][debug][os] Symbol JNI_OnLoad_zip not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/bin/java: undefined symbol: JNI_OnLoad_zip
[0.381s][debug][os] rss accurate: 24465408
RSS: 24465408
Host available memory: 16295006208
[0.446s][debug][os] Symbol JNI_OnLoad_jimage not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/bin/java: undefined symbol: JNI_OnLoad_jimage
[0.447s][info ][os] attempting shared library load of /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjimage.so
[0.447s][info ][os] shared library load of /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjimage.so was successful
[0.447s][debug][os] Symbol JNI_OnLoad not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjimage.so: undefined symbol: JNI_OnLoad
[0.447s][debug][os] Symbol Java_jdk_internal_jimage_NativeImageBuffer_getNativeMap not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libjava.so: undefined symbol: Java_jdk_internal_jimage_NativeImageBuffer_getNativeMap
[0.447s][debug][os] Symbol Java_jdk_internal_jimage_NativeImageBuffer_getNativeMap not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libzip.so: undefined symbol: Java_jdk_internal_jimage_NativeImageBuffer_getNativeMap
[0.447s][debug][os] Symbol Java_jdk_internal_jimage_NativeImageBuffer_getNativeMap not found in dll: /priv/jvmtests/output_openjdk26_stage_optU_linuxx86_64/testee-vm/lib/libnio.so: undefined symbol: Java_jdk_internal_jimage_NativeImageBuffer_getNativeMap
----------System.err:(13/1278)----------
java.lang.RuntimeException: RSS of this process(24465408b) should be bigger than or equal to heap size(268435456b) (available memory: 16295006208). On Linux Kernel < 4.14 RSS can be inaccurate: expected 24465408 > 268435456
at jdk.test.lib.Asserts.fail(Asserts.java:715)
at jdk.test.lib.Asserts.assertGreaterThan(Asserts.java:403)
at gc.TestAlwaysPreTouchBehavior.main(TestAlwaysPreTouchBehavior.java:157)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
at java.base/java.lang.Thread.run(Thread.java:1474)