Bug #81679 [Asn->Ver]: PHP 8 opcache crashing when using JIT on Windows 2019

Edit report at https://bugs.php.net/bug.php?id=81679&edit=1 ID: 81679 Updated by: cmb@php.net Reported by: alex at ndros dot com Summary: PHP 8 opcache crashing when using JIT on Windows 2019 -Status: Assigned +Status: Verified Type: Bug Package: JIT Operating System: Windows Server 2019 PHP Version: 8.0.13 Assigned To: cmb Block user comment: N Private report: N New Comment: It seems to me that the current tracing JIT implementation is broken for any multiprocess Web SAPIs which *re*attach to OPcache SHM (generally (F)CGI, but on Windows potentially any SAPI which may run multiple PHP processes in parallel, unless they enforce separate OPcache instances). The problem begins in zend_jit_trace_startup[1] where SHM memory is allocated for zend_jit_traces and zend_jit_exit_groups, but that would be reallocated whenever a new process attaches to OPcache SHM. And that appears to be the reason for the stack backtrace presented above: where zend_jit_traces is not properly initialized to what has been calculated previously, and as such causes a segfault. That might be fixable without ABI break, but otherwise we should make sure that tracing JIT is not available for such environments. [1] <https://github.com/php/php-src/blob/php-8.0.13/ext/opcache/jit/zend_jit_trace.c#L51> Previous Comments: ------------------------------------------------------------------------ [2021-12-08 13:57:54] cmb@php.net Thanks for further input! > From basic observation this seems to happen as soon as a second > FastCGI php-cgi instance is started by IIS Ah, right, something is wrong there. I need to investigate. ------------------------------------------------------------------------ [2021-12-08 12:16:49] ian dot fitzgerald at emapplications dot com We also have this issue with our Wordpress website on Server 2019 after upgrading PHP7.3->8.0 and enabling opcache+JIT. From basic observation this seems to happen as soon as a second FastCGI php-cgi instance is started by IIS (instance limit set to 4). I have generated this stack backtrace: Faulting Thread entry point: php_cgi!mainCRTStartup php_opcache!zend_jit_trace_exit+7d [D:\a\php-ftw\php-ftw\php\vs16\x64\php-8.0.13\ext\opcache\jit\zend_jit_trace.c @ 7443 + 14] 0x00001000`080005cb 0x0000025d`00000003 0x0000009f`445fb630 0x0000025d`9d753e00 php8!zend_fetch_class+a0 [D:\a\php-ftw\php-ftw\php\vs16\x64\php-8.0.13\Zend\zend_execute_API.c @ 1509 + 9] Exception information: xxxx.dmp the assembly instruction at php_opcache!zend_jit_trace_exit+7d in C:\Program Files\php8\ext\php_opcache.dll from The PHP Group has caused an access violation exception (0xC0000005) when trying to read from memory location 0x00000074 on thread 0 ------------------------------------------------------------------------ [2021-12-01 11:03:22] cmb@php.net I cannot reproduce this. > This seem to happen to any PHP application. Can you give a concrete example? Ideally, a minimal application or even better a simple script. A stack backtrace[1] might also be helpful. [1] <https://bugs.php.net/bugs-generating-backtrace-win32.php> ------------------------------------------------------------------------ [2021-11-30 22:50:49] alex at ndros dot com This seem to happen to any PHP application. ------------------------------------------------------------------------ [2021-11-30 22:50:04] alex at ndros dot com Description: ------------ Hi! We have discovered that as soon as we turn on jit with the following config; opcache.jit_buffer_size=64M opcache.jit=tracing We (what it seems to be randomly) get crashes. Also, CPU get's compeltely bottlenecked at 100% until we do IISRESET. C:\Program Files\PHP\v8.0\php-cgi.exe - The FastCGI process exited unexpectedly Module FastCgiModule Handler php-8.0.13 Error Code 0xc0000005 ----- Faulting application name: php-cgi.exe, version: 8.0.13.0, time stamp: 0x619429f5 Faulting module name: php_opcache.dll, version: 8.0.13.0, time stamp: 0x61942d4a Exception code: 0xc0000005 Fault offset: 0x000000000012a7cd Faulting process id: 0x8b38 Faulting application start time: 0x01d7e63c092eb6ad Faulting application path: C:\Program Files\PHP\v8.0\php-cgi.exe Faulting module path: C:\Program Files\PHP\v8.0\ext\php_opcache.dll Report Id: c9a1f978-17d7-4a3f-a340-3051ebe97f58 Faulting package full name: Faulting package-relative application ID: --- Fault bucket 1348990199055715320, type 4 Event Name: APPCRASH Response: Not available Cab Id: 0 Problem signature: P1: php-cgi.exe P2: 8.0.13.0 P3: 619429f5 P4: php_opcache.dll P5: 8.0.13.0 P6: 61942d4a P7: c0000005 P8: 000000000012a7cd P9: P10: Attached files: \\?\C:\ProgramData\Microsoft\Windows\WER\Temp\WER8F67.tmp.dmp \\?\C:\ProgramData\Microsoft\Windows\WER\Temp\WER8FE5.tmp.WERInternalMetadata.xml \\?\C:\ProgramData\Microsoft\Windows\WER\Temp\WER9005.tmp.xml \\?\C:\ProgramData\Microsoft\Windows\WER\Temp\WER9019.tmp.csv \\?\C:\ProgramData\Microsoft\Windows\WER\Temp\WER9039.tmp.txt These files may be available here: \\?\C:\ProgramData\Microsoft\Windows\WER\ReportArchive\AppCrash_php-cgi.exe_2058cbb22b56eff0f71936402f536fd764c1aa4d_4a81e604_b0659449 Analysis symbol: Rechecking for solution: 0 Report Id: c9a1f978-17d7-4a3f-a340-3051ebe97f58 Report Status: 268435456 Hashed bucket: 407a7897610279d7c2b8937054330bf8 Cab Guid: 0 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=81679&edit=1