12:20 p.m.
On 26.09.2016 14:29, Richard W.M. Jones wrote:
On Mon, Sep 26, 2016 at 02:18:02PM +0200, Carl-Daniel Hailfinger
wrote:
> Hi,
>
> has anyone ever run "make check" from nbd against nbdkit with a python
> plugin? I usually get segfaults during such a run, and sometimes various
> other errors happen before the segfault, suggesting that some memory
> corruption is underway.
> AFAICS a pure python plugin should not be able to cause memory corruption.
Correct, a python plugin should not cause memory corruption,
and nbdkit shouldn't segfault ever.
Did you get a stack trace from C (not from Python)?
The core files were useless, but I ran nbdkit in gdb and got something...
(gdb) run -n -f /software/nbdkit/plugins/python/.libs/nbdkit-python-plugin.so
script=/software/nbdkit/plugins/python/ssd-ftl-wearleveling.py disksize=52428800
Starting program: /software/nbdkit/src/nbdkit -n -f
/software/nbdkit/plugins/python/.libs/nbdkit-python-plugin.so
script=/software/nbdkit/plugins/python/ssd-ftl-wearleveling.py disksize=52428800
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Breakpoint 1, py_config (key=0x7fffffffe2e0 "script", value=0x7fffffffe2e7
"/software/nbdkit/plugins/python/ssd-ftl-wearleveling.py") at python.c:107
107 {
(gdb) info shared
From To Syms Read Shared Object
Library
0x00007ffff7ddaae0 0x00007ffff7df5490 Yes
/lib64/ld-linux-x86-64.so.2
0x00007ffff7bd6ed0 0x00007ffff7bd79ce Yes /lib/x86_64-linux-gnu/libdl.so.2
0x00007ffff79bd9f0 0x00007ffff79ca471 Yes /lib/x86_64-linux-gnu/libpthread.so.0
0x00007ffff7612520 0x00007ffff7757183 Yes /lib/x86_64-linux-gnu/libc.so.6
0x00007ffff73f0000 0x00007ffff73f13e7 Yes
/software/nbdkit/plugins/python/.libs/nbdkit-python-plugin.so
0x00007ffff6ed70c0 0x00007ffff7065782 Yes (*)
/usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
0x00007ffff6c73e00 0x00007ffff6c83bf8 Yes /lib/x86_64-linux-gnu/libz.so.1
0x00007ffff6a6ff10 0x00007ffff6a70804 Yes /lib/x86_64-linux-gnu/libutil.so.1
0x00007ffff676e610 0x00007ffff67dd056 Yes /lib/x86_64-linux-gnu/libm.so.6
(*): Shared library is missing debugging information.
(gdb) c
Continuing.
[New Thread 0x7ffff62eb700 (LWP 24498)]
[Thread 0x7ffff62eb700 (LWP 24498) exited]
[New Thread 0x7ffff62eb700 (LWP 24516)]
[Thread 0x7ffff62eb700 (LWP 24516) exited]
[New Thread 0x7ffff62eb700 (LWP 24519)]
[Thread 0x7ffff62eb700 (LWP 24519) exited]
[New Thread 0x7ffff62eb700 (LWP 24536)]
[Thread 0x7ffff62eb700 (LWP 24536) exited]
[New Thread 0x7ffff62eb700 (LWP 24549)]
[Thread 0x7ffff62eb700 (LWP 24549) exited]
[New Thread 0x7ffff62eb700 (LWP 24561)]
[New Thread 0x7ffff4c26700 (LWP 24580)]
nbdkit: python[6]: error: ssd-ftl-wearleveling.py: callback failed: close
[Thread 0x7ffff62eb700 (LWP 24561) exited]
nbdkit: python[7]: error: invalid flush request: expecting offset and length == 0
nbdkit: python[7]: error: write reply: Connection reset by peer
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff4c26700 (LWP 24580)]
0x00007ffff7015306 in PyEval_EvalFrameEx () from
/usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
(gdb) bt
#0 0x00007ffff7015306 in PyEval_EvalFrameEx () from
/usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
#1 0x00007ffff7018059 in PyEval_EvalFrameEx () from
/usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
#2 0x00007ffff7018059 in PyEval_EvalFrameEx () from
/usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
#3 0x00007ffff701954d in PyEval_EvalCodeEx () from
/usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
#4 0x00007ffff7017dd8 in PyEval_EvalFrameEx () from
/usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
#5 0x00007ffff701954d in PyEval_EvalCodeEx () from
/usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
#6 0x00007ffff704e6d0 in ?? () from /usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
#7 0x00007ffff6fbad43 in PyObject_Call () from
/usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
#8 0x00007ffff7033577 in PyEval_CallObjectWithKeywords () from
/usr/lib/x86_64-linux-gnu/libpython2.7.so.1.0
#9 0x00007ffff73f0af0 in py_close (handle=0x625338) at python.c:234
#10 0x0000000000405803 in plugin_close (conn=conn@entry=0x7fffe8000910) at plugins.c:377
#11 0x00000000004037ec in free_connection (conn=0x7fffe8000910) at connections.c:147
#12 0x0000000000404476 in _handle_single_connection (sockout=<optimized out>,
sockin=<optimized out>) at connections.c:99
#13 handle_single_connection (sockin=<optimized out>, sockout=<optimized out>)
at connections.c:109
#14 0x0000000000405e73 in start_thread (datav=0x7fffffffdd40) at sockets.c:220
#15 0x00007ffff79c0184 in start_thread (arg=0x7ffff4c26700) at pthread_create.c:312
#16 0x00007ffff76ed37d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
Regards,
Carl-Daniel
Rich.
> Examples of nbdkit logs for running "make check" or subsets of it from
> nbd against nbdkit:
>
> nbdkit -n -f python script=ssd-ftl-wearleveling.py disksize=52428800
> nbdkit: python[6]: error: ssd-ftl-wearleveling.py: callback failed: close
> nbdkit: python[7]: error: invalid flush request: expecting offset and
> length == 0
> nbdkit: python[7]: error: write reply: Connection reset by peer
> Segmentation fault
>
> nbdkit -n -f python script=ssd-ftl-wearleveling.py disksize=52428800
> Fatal Python error: GC object already tracked
> Segmentation fault
>
> nbdkit -n -f python script=ssd-ftl-wearleveling.py disksize=52428800
> Segmentation fault
>
> nbdkit -n -f python script=ssd-ftl-wearleveling.py disksize=52428800
> nbdkit: python[1]: error: invalid flush request: expecting offset and
> length == 0
> nbdkit: python[1]: error: write reply: Broken pipe
> nbdkit: python[3]: error: client sent NBD_OPT_ABORT to abort the connection
> nbdkit: python[6]: error: ssd-ftl-wearleveling.py: callback failed: close
> Traceback (most recent call last):
> File "ssd-ftl-wearleveling.py", line 221, in close
> pickle.dump(lbahist, f)
> File "/usr/lib/python2.7/pickle.py", line 1370, in dump
> Segmentation fault (core dumped)
>
> My close function just dumps the disk image and write access history
> with python pickle. It does not have any return statement, and because
> of that I seriously doubt that said close function can fail.
>
> I'm now trying to replicate this with example.py. Will report back.
>
> Regards,
> Carl-Daniel
>
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