Re: Php-fpm will crash when perf runs with call graph option

[Jiri Olsa <jolsa@redhat.com>]

On Mon, Dec 25, 2017 at 07:56:43AM +0100, ufo19890607 wrote:
> From: yuzhoujian <yuzhoujian@didichuxing.com>
> 
> #0  0x00007f044ff447bd in re_compile_fastmap_iter (bufp=0x7f044ff447bd <re_compile_fastmap_iter+1165>, 
> 		    fastmap=0x46 <Address 0x46 out of bounds>, init_state=<optimized out>, init_state=<optimized out>) at regcomp.c:407
> 407			      if (__wcrtomb (buf, towlower (cset->mbchars[i]), &state)
> 		(gdb) bt
> #0  0x00007f044ff447bd in re_compile_fastmap_iter (bufp=0x7f044ff447bd <re_compile_fastmap_iter+1165>, 
> 	    fastmap=0x46 <Address 0x46 out of bounds>, init_state=<optimized out>, init_state=<optimized out>) at regcomp.c:407
> #1  0x0000000000831160 in virtual_file_ex (state=0x7fff9c1a4f70, path=<optimized out>, verify_path=0x0, use_realpath=1)
> 		    at /home/xiaoju/phpng/php-7.0.6/Zend/zend_virtual_cwd.c:1335
> #2  0x00000000007aacee in expand_filepath_with_mode (
> 	    filepath=0x7f044d6020d8 "/home/xiaoju/ep/as/store//toggles/beatles_api_discovery_is_open_by_app", 
> 	        real_path=0x7fff9c1a4fc0 "\360X\032\234\377\177", relative_to=<optimized out>, relative_to_len=0, realpath_mode=1)
> 		        at /home/xiaoju/phpng/php-7.0.6/main/fopen_wrappers.c:812
> #3  0x00000000007c1536 in _php_stream_fopen (
> 	    filename=0x7f044d6020d8 "/home/xiaoju/ep/as/store//toggles/beatles_api_discovery_is_open_by_app", mode=0xdbb1f1 "rb", 
> 	        opened_path=0x0, options=0) at /home/xiaoju/phpng/php-7.0.6/main/streams/plain_wrapper.c:970
> #4  0x00000000007bd084 in _php_stream_open_wrapper_ex (
> 	    path=0x7f044d6020d8 "/home/xiaoju/ep/as/store//toggles/beatles_api_discovery_is_open_by_app", mode=0xdbb1f1 "rb", options=8, 
> 	        opened_path=0x0, context=0x7f044d65f4c0) at /home/xiaoju/phpng/php-7.0.6/main/streams/streams.c:2060
> #5  0x000000000071722b in zif_file_get_contents (execute_data=<optimized out>, return_value=0x7f044d615540)
> 			    at /home/xiaoju/phpng/php-7.0.6/ext/standard/file.c:544
> #6  0x000000000065387c in phar_file_get_contents (execute_data=0x7f044d615570, return_value=0x7f044d615540)
> 			        at /home/xiaoju/phpng/php-7.0.6/ext/phar/func_interceptors.c:224))
> 
> I add some output info in the php source code, and found that virtual_file_ex functions's rbp value is really strange,etc 0x1, 0x31. I guess when the perf collects samples for all the cpus with -g option, it may destroy the php-fpm's stack. When the perf is running without -g option, the php-fpm is normal. Who have ever encountered similar problems?

hum, except for speed there shouldn't be other influence on perf-ed program,
does it happen always? whats the perf record's command line?

it's possible you're hitting some php-fpm race issue due to the speed degradation

> BTW, OS in the server: Centos7.3  , Kernel version: 3.10.0-514.16.1.el7.x86_64. php-fpm version: 7.0.6 
> Processor info: Intel(R) Xeon(R) CPU E5-2620 v3 @ 2.40GHz 

is there a single way to reproduce?

As already mentioned by Wang, does it happen on recent kernel?

thanks,
jirka