Missing copyright #12
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Similar feedback to previous commit :-) . Once that is done I'll go ahead and merge this. |
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Is this something that we could request to be added upstream? |
sdimitro
approved these changes
Jun 5, 2020
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@ahrens The upstream drgn repository doesn't generate deb packages and does not have a debian folder in the root directory. Thus this commit by itself cannot make it upstream. Now if the question was whether we should request upstream drgn to have a debian directory for people who want to generate packages, I believe that we could do that. It would take some effort though as we can't just use that try to upstream our debian directory. The reason is that our directory's contents are pretty minimal and specific because they depend on functionality provided by linux-pkg which builds the package for us. |
ahrens
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Jun 5, 2020
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Sep 27, 2025
The CI has intermittently been hitting the following test failures on
Python 3.8 with Clang:
======================================================================
ERROR: test_task_cpu (tests.linux_kernel.helpers.test_sched.TestSched)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/runner/work/drgn/drgn/tests/linux_kernel/helpers/test_sched.py", line 40, in test_task_cpu
with fork_and_stop(os.sched_setaffinity, 0, (cpu,)) as (pid, _):
File "/opt/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/contextlib.py", line 113, in __enter__
return next(self.gen)
File "/home/runner/work/drgn/drgn/tests/linux_kernel/__init__.py", line 203, in fork_and_stop
ret = pickle.load(pipe_r)
EOFError: Ran out of input
The EOFError occurs because the forked process segfaults immediately:
python[132]: segfault at 7f8f87085014 ip 00007f8f891e9774 sp 00007ffccf7acf00 error 4 in ld-linux-x86-64.so.2[16774,7f8f891d5000+2a000] likely on CPU 0 (core 0, socket 0)
The segfault is on dereferencing cache_new in in _dl_load_cache_lookup()
in ld-linux here:
https://sourceware.org/git/?p=glibc.git;a=blob;f=elf/dl-cache.c;h=88bf78ad7c914b02109d6ddef7e08c0e8fd4574d;hb=f94f6d8a3572840d3ba42ab9ace3ea522c99c0c2#l489
Which is coming from a libomp fork handler:
#0 0x00007f5566f9d774 in _dl_load_cache_lookup (name=name@entry=0x7f55654afde6 "libmemkind.so")
at ./elf/dl-cache.c:498
#1 0x00007f5566f91982 in _dl_map_object (loader=loader@entry=0x55f8a170b670,
name=name@entry=0x7f55654afde6 "libmemkind.so", type=type@entry=2, trace_mode=trace_mode@entry=0,
mode=mode@entry=-1879048191, nsid=<optimized out>) at ./elf/dl-load.c:2193
#2 0x00007f5566f959a9 in dl_open_worker_begin (a=a@entry=0x7fffcf5851f0) at ./elf/dl-open.c:534
#3 0x00007f5566b4ab08 in __GI__dl_catch_exception (exception=exception@entry=0x7fffcf585050,
operate=operate@entry=0x7f5566f95900 <dl_open_worker_begin>, args=args@entry=0x7fffcf5851f0)
at ./elf/dl-error-skeleton.c:208
#4 0x00007f5566f94f9a in dl_open_worker (a=a@entry=0x7fffcf5851f0) at ./elf/dl-open.c:782
#5 0x00007f5566b4ab08 in __GI__dl_catch_exception (exception=exception@entry=0x7fffcf5851d0,
operate=operate@entry=0x7f5566f94f60 <dl_open_worker>, args=args@entry=0x7fffcf5851f0)
at ./elf/dl-error-skeleton.c:208
#6 0x00007f5566f9534e in _dl_open (file=<optimized out>, mode=-2147483647, caller_dlopen=0x7f55653fa882, nsid=-2,
argc=9, argv=<optimized out>, env=0x55f8a1477e10) at ./elf/dl-open.c:883
#7 0x00007f5566a6663c in dlopen_doit (a=a@entry=0x7fffcf585460) at ./dlfcn/dlopen.c:56
#8 0x00007f5566b4ab08 in __GI__dl_catch_exception (exception=exception@entry=0x7fffcf5853c0, operate=<optimized out>,
args=<optimized out>) at ./elf/dl-error-skeleton.c:208
#9 0x00007f5566b4abd3 in __GI__dl_catch_error (objname=0x7fffcf585418, errstring=0x7fffcf585420,
mallocedp=0x7fffcf585417, operate=<optimized out>, args=<optimized out>) at ./elf/dl-error-skeleton.c:227
#10 0x00007f5566a6612e in _dlerror_run (operate=operate@entry=0x7f5566a665e0 <dlopen_doit>,
args=args@entry=0x7fffcf585460) at ./dlfcn/dlerror.c:138
#11 0x00007f5566a666c8 in dlopen_implementation (dl_caller=<optimized out>, mode=<optimized out>, file=<optimized out>)
at ./dlfcn/dlopen.c:71
#12 ___dlopen (file=<optimized out>, mode=<optimized out>) at ./dlfcn/dlopen.c:81
#13 0x00007f55653fa882 in ?? () from /usr/lib/llvm-14/lib/libomp.so.5
#14 0x00007f5565413556 in ?? () from /usr/lib/llvm-14/lib/libomp.so.5
#15 0x00007f5565421d1a in ?? () from /usr/lib/llvm-14/lib/libomp.so.5
#16 0x00007f5566ac0fc1 in __run_fork_handlers (who=who@entry=atfork_run_child, do_locking=do_locking@entry=true)
at ./posix/register-atfork.c:130
#17 0x00007f5566ac08d3 in __libc_fork () at ./posix/fork.c:108
#18 0x00007f5566e108ad in os_fork_impl (module=<optimized out>) at ./Modules/posixmodule.c:6250
#19 os_fork (module=<optimized out>, _unused_ignored=<optimized out>) at ./Modules/clinic/posixmodule.c.h:2750
This doesn't happen in Python 3.9, which I bisected to CPython commit
45a78f906d2d ("bpo-44434: Don't call PyThread_exit_thread() explicitly
(GH-26758)") (in v3.11, backported to v3.9.6).
That commit describes a different symptom where the process aborts
because libgcc_s can't be loaded. I don't understand how that issue can
cause our crash, but the fix appears to be the same. The discussion also
suggests a workaround: linking to libgcc_s explicitly.
Apply the workaround, which appears to fix our problem. We only do this
for the CI and not for the general build for a few reasons:
1. I'm nervous about explicitly linking to this low-level library
unconditionally, and the logic to decide when it's necessary (only
for Python 3.8 and glibc) isn't worth the trouble.
2. The situation required to hit it (drgn + Python threading + fork) is
unlikely outside of our test suite.
3. Python 3.8 is EOL.
4. Builds with libkdumpfile already pull in libgcc_s via libkdumpfile ->
libsnappy -> libstdc++ -> libgcc_s.
Signed-off-by: Omar Sandoval <[email protected]>
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