PHP-FPM segfault in OPcache with PHP 8.4.10

Description

Our PHP-FPM crashes at seemingly random moments with an error in OPcache. I am unable to reproduce this locally but have made coredumps on production. They seem to result in 2 distinct backtraces that seem to point to the same error:

[New LWP 46774]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `php-fpm: pool www             '.
Program terminated with signal SIGSEGV, Segmentation fault.

(gdb) bt

#0  0x00007f596e4f5b91 in ?? ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#1  0x00007f596e4f72c9 in ?? ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#2  0x00007f596e4f7db0 in zend_file_cache_script_store ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#3  0x00007f596e50a880 in persistent_compile_file ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#4  0x000055afdce6ea46 in compile_filename ()
#5  0x000055afdce01580 in ?? ()
#6  0x000055afdce0f689 in ?? ()
#7  0x000055afdce3bb0d in execute_ex ()
#8  0x000055afdce39f83 in zend_execute ()
#9  0x000055afdcea1a40 in zend_execute_script ()
#10 0x000055afdcd3f085 in php_execute_script_ex ()
#11 0x000055afdca09a5a in ?? ()
#12 0x00007f59715b624a in __libc_start_call_main (main=main@entry=0x55afdca08d10, 
    argc=argc@entry=2, argv=argv@entry=0x7ffe5eb3ef78)
    at ../sysdeps/nptl/libc_start_call_main.h:58
#13 0x00007f59715b6305 in __libc_start_main_impl (main=0x55afdca08d10, argc=2, 
    argv=0x7ffe5eb3ef78, init=<optimized out>, fini=<optimized out>, 
    rtld_fini=<optimized out>, stack_end=0x7ffe5eb3ef68) at ../csu/libc-start.c:360
#14 0x000055afdca0ba31 in _start ()

Program terminated with signal SIGSEGV, Segmentation fault.

(gdb) bt

#0  0x00007f596e4f5b91 in ?? ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#1  0x00007f596e4f72c9 in ?? ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#2  0x00007f596e4f5cb5 in ?? ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#3  0x00007f596e4f64d0 in ?? ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#4  0x00007f596e4f5cb5 in ?? ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#5  0x00007f596e4f7d82 in zend_file_cache_script_store ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#6  0x00007f596e50a880 in persistent_compile_file ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/opcache.so
#7  0x000055afdce6ea46 in compile_filename ()
#8  0x000055afdce01580 in ?? ()
#9  0x000055afdce0f689 in ?? ()
#10 0x000055afdce3bb0d in execute_ex ()
#11 0x000055afdcdeb0cd in zend_call_function ()
#12 0x000055afdcdeb4dd in zend_call_known_function ()
#13 0x000055afdcc61f86 in ?? ()
#14 0x00007f596cc2564b in tideways_hooks_perform_autoload ()
   from /usr/local/lib/php/extensions/no-debug-non-zts-20240924/tideways.so
#15 0x000055afdcdea31e in zend_lookup_class_ex ()
#16 0x000055afdcdeb8e0 in zend_fetch_class_by_name ()
#17 0x000055afdce0cde7 in ?? ()
#18 0x000055afdce3bcd4 in execute_ex ()
#19 0x000055afdce39f83 in zend_execute ()
#20 0x000055afdcea1a40 in zend_execute_script ()
#21 0x000055afdcd3f085 in php_execute_script_ex ()
#22 0x000055afdca09a5a in ?? ()
#23 0x00007f59715b624a in __libc_start_call_main (main=main@entry=0x55afdca08d10, 
    argc=argc@entry=2, argv=argv@entry=0x7ffe5eb3ef78)
    at ../sysdeps/nptl/libc_start_call_main.h:58
#24 0x00007f59715b6305 in __libc_start_main_impl (main=0x55afdca08d10, argc=2, 
    argv=0x7ffe5eb3ef78, init=<optimized out>, fini=<optimized out>, 
    rtld_fini=<optimized out>, stack_end=0x7ffe5eb3ef68) at ../csu/libc-start.c:360
#25 0x000055afdca0ba31 in _start ()

I am out of my league in debugging this myself, and there's little I can change to the setup to narrow it down. Hopefully the backtraces help. If there's any additional context or hint of reproduction steps I can try please let me know.

PHP Version

PHP 8.4.10 (cli) (built: Jul  3 2025 22:57:54) (NTS)
Copyright (c) The PHP Group
Built by https://github.com/docker-library/php
Zend Engine v4.4.10, Copyright (c) Zend Technologies
    with Zend OPcache v8.4.10, Copyright (c), by Zend Technologies

Operating System

No response

Start with the PHP 8.4.10 coredumps and the OPcache frames around zend_file_cache_script_store() and persistent_compile_file(); the second trace also includes tideways_hooks_perform_autoload() from tideways.so. Use the available GDB backtraces to narrow the failing OPcache path and seek a reproducible case. Done means a confirmed cause with a regression test or a documented fix.