Segmentation fault in gc_collect_cycles()

Problem/Motivation

https://www.drupal.org/pift-ci-job/670070 - https://dispatcher.drupalci.org/job/drupal_patches/15398/artifact/jenkin...

Program terminated with signal SIGSEGV, Segmentation fault.
#0  zval_scan (pz=0x0) at /usr/src/php/Zend/zend_gc.c:511
511		if (GC_ZVAL_GET_COLOR(pz) == GC_GREY) {
#0  zval_scan (pz=0x0) at /usr/src/php/Zend/zend_gc.c:511
#1  0x0000000000889b85 in zval_scan (pz=<optimized out>)
    at /usr/src/php/Zend/zend_gc.c:563
#2  0x0000000000889bb5 in zval_scan (pz=<optimized out>)
    at /usr/src/php/Zend/zend_gc.c:539
#3  0x0000000000889bb5 in zval_scan (pz=<optimized out>)
    at /usr/src/php/Zend/zend_gc.c:539
#4  0x0000000000889b85 in zval_scan (pz=<optimized out>)
    at /usr/src/php/Zend/zend_gc.c:563
#5  0x0000000000889bb5 in zval_scan (pz=<optimized out>)
    at /usr/src/php/Zend/zend_gc.c:539
#6  0x0000000000889bb5 in zval_scan (pz=<optimized out>)
    at /usr/src/php/Zend/zend_gc.c:539
#7  0x0000000000889b85 in zval_scan (pz=<optimized out>)
    at /usr/src/php/Zend/zend_gc.c:563
#8  0x0000000000889f1a in gc_scan_roots () at /usr/src/php/Zend/zend_gc.c:622
#9  gc_collect_cycles () at /usr/src/php/Zend/zend_gc.c:791
#10 0x000000000088a6c9 in gc_zval_possible_root (zv=0x3a46d58)
    at /usr/src/php/Zend/zend_gc.c:163
#11 0x0000000000916b45 in gc_zval_check_possible_root (z=<optimized out>)
    at /usr/src/php/Zend/zend_gc.h:183
#12 i_zval_ptr_dtor (zval_ptr=<optimized out>)
    at /usr/src/php/Zend/zend_execute.h:86
#13 zend_vm_stack_clear_multiple (nested=<optimized out>)
    at /usr/src/php/Zend/zend_execute.h:308
#14 zend_do_fcall_common_helper_SPEC (execute_data=0x7fbcd3655df8)
    at /usr/src/php/Zend/zend_vm_execute.h:650
#15 0x00000000008a1840 in execute_ex (execute_data=0x7fbcd3655df8)
    at /usr/src/php/Zend/zend_vm_execute.h:363
#16 0x000000000086c340 in zend_execute_scripts (type=0, type@entry=8,
    retval=0x7ffe6dba9d08, retval@entry=0x0, file_count=0, file_count@entry=3)
    at /usr/src/php/Zend/zend.c:1341
#17 0x000000000080ad18 in php_execute_script (primary_file=0x7ffe6dbac4d0)
    at /usr/src/php/main/main.c:2613
#18 0x0000000000918a31 in do_cli (argc=0, argv=0x7ffe6dba9d08)
    at /usr/src/php/sapi/cli/php_cli.c:998
#19 0x0000000000443277 in main (argc=0, argv=0x7ffe6dba9d08)
    at /usr/src/php/sapi/cli/php_cli.c:1382
[0x7fbcd3655df8] drupal_rewrite_settings() /var/www/html/core/includes/install.inc:243
[0x7fbcd3655c98] drupal_rewrite_settings(array(2)[0x4ef0018], "sites/simpletest/28620959/settings.php") /var/www/html/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php:135
[0x7fbcd3655b00] Drupal\simpletest\WebTestBase->writeSettings(array(2)[0x4ef0018]) /var/www/html/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php:84
[0x7fbcd36559c0] Drupal\simpletest\WebTestBase->prepareSettings() /var/www/html/core/modules/simpletest/src/WebTestBase.php:424
[0x7fbcd36558a0] Drupal\simpletest\WebTestBase->setUp() /var/www/html/core/modules/comment/src/Tests/CommentTestBase.php:49
[0x7fbcd3655730] Drupal\comment\Tests\CommentTestBase->setUp() /var/www/html/core/modules/rdf/src/Tests/CommentAttributesTest.php:40
[0x7fbcd36554e0] Drupal\rdf\Tests\CommentAttributesTest->setUp() /var/www/html/core/modules/simpletest/src/TestBase.php:947
[0x7fbcd3655318] Drupal\simpletest\TestBase->run(array(0)[0x2f6f4f8]) /var/www/html/core/scripts/run-tests.sh:793
[0x7fbcd3655158] simpletest_script_run_one_test("1658", "Drupal\rdf\Tests\CommentAttributesTest") /var/www/html/core/scripts/run-tests.sh:67

This might be related to some of the segfaults seen on #2859704: Intermittent segfaults on DrupalCI (some "did not complete due to a fatal error" with no additional info)

The classes this has been seen in are:

• Drupal\rdf\Tests\CommentAttributesTest::testCommentReplyOfRdfaMarkup()

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes