#717: parrot_config segfaults when invoked with the --dump option
--------------------+-------------------------------------------------------
Reporter: Util | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: none | Version: trunk
Severity: high | Keywords: GC parrot_config dump
Lang: perl6 | Patch:
Platform: |
--------------------+-------------------------------------------------------
= Summary =
parrot_config segfaults when invoked with the --dump option. This occurs
in any form of invocation:
* `./parrot_config --dump`
* `./parrot parrot_config.pbc --dump`
* `./parrot tools/util/parrot-config.pir --dump`
When the `./parrot` variants are also invoked with the `-G` option (to
disable garbage collection), the output completes normally.
This ticket is flagged as language:perl6 because Rakudo users are
reporting "Reading configuration information from parrot/parrot_config
...Died at Configure.pl line 104."
Rakudo's Configure.pl is failing when it tries to run `./parrot_config
--dump`.
= Research =
(I think) I traced the problem to the use of a "fake" STRING in
Parrot_io_write() in src/io/api.c.
My GC skills were not strong enough to fix the issue, but I wrote a work-
around patch that reduces the use of "fake" to the point that
`parrot_config --dump` succeeds.
The patch optimizes the common case of the single newline that `say`
emits.
Note: I do not recommend that the patch be applied to SVN trunk. It is a
workaround only.
= Original report =
trimmed from http://irclog.perlgeek.de/parrot/2009-05-19 :
{{{
18:25 Util With Parrot r38941, on darwin, plus one patch that
does not affect config, running `./parrot parrot_config.pbc --dump` prints
the first 12 lines, then "Bus error".
18:25 Util Disabling GC allows all lines to print. `./parrot -G
parrot_config.pbc --dump`.
18:25 Util My build passes all tests in `make test`.
18:25 Util BTW, I do not see anywhere that we exercise
parrot_config in t/*.
18:25 Util Can anyone duplicate the issue?
18:26 Whiteknight davidfetter: Nobody that I know of
18:27 jonathan Util: Any chance of a backtrace?
18:28 Whiteknight Util: and what's the patch?
18:29 Util Whiteknight: patch is the latest in my uncommitted
pbc_to_exe efforts. That is why I am invoking with the parrot+.pbc call,
instead of `./parrot_config`
18:34 nopaste "Util" at 68.191.99.24 pasted "parrot_config.pbc
backtrace" (94 lines) at http://nopaste.snit.ch/16609
18:38 jonathan Util: Oh gee, it's actually segfaulting *inside* the
GC...
18:39 jonathan holy s**t...doing a write goes through 3 layers of
PCCINVOKES?!
18:39 Whiteknight somewhere it looks like a Context is holding a bogus
pointer, Unused pointers should be NULL'd in Contexts
18:40 jonathan Whiteknight: Yeah.
18:40 Whiteknight yeah, the IO system really utilizes it's PMCs
18:40 Whiteknight All the more reason to (1) get PCC optimized and (2)
to get asynchronous IO working
18:40 jonathan Whiteknight: I'm wondering if the something inside
PCCINVOKE maybe doesn't init the outer pointer or something...
18:41 chromatic That could be a context change I committed the other
day to avoid calloc.
18:41 Whiteknight weird that it would only show up in such a particular
stack trace
18:41 jonathan Whiteknight: We probably often don't call 3 levels of
PCCINVOKES...
18:42 chromatic It makes sense to me. If there's an uninitialized
struct member....
18:42 Whiteknight 0xbffff570, is that a protected address on darwin?
18:42 jonathan chromatic: I can only guess it normally gets
initialized when doing stuff in PIR and the PCCINVOKE path leaves a junk
value.
18:42 chromatic That could be.
18:42 Whiteknight or is does that PMC itself contain the bad pointer?
18:44 Whiteknight no, I take that back, 0xbffff570 is the bad address
18:45 jonathan oh ouch
18:45 jonathan for (i = 0; i < ctx->n_regs_used[REGNO_STR]; ++i) {
18:45 jonathan obj = (PObj *)CTX_REG_STR(ctx, i);
18:45 jonathan if (obj)
18:45 jonathan Parrot_gc_mark_PObj_alive(interp, obj);
18:45 jonathan It's that which is passing the bad pointer, it seems.
18:45 jonathan (Line 124 is that last one)
19:10 Util parrot_config issue update - I tried a fresh checkout,
with no patches. It has the exact same problem.
}}}
= Backtrace =
originally submitted as http://nopaste.snit.ch/16609 :
{{{
$ gdb ./parrot_config
GNU gdb 6.3.50-20050815 (Apple version gdb-696) (Sat Oct 20 18:16:54 GMT
2007)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you
are
welcome to change it and/or distribute copies of it under certain
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for
details.
This GDB was configured as "i386-apple-darwin"...
warning: --arch option not supported in this gdb.
Reading symbols for shared libraries ........ done
(gdb) run --dump
Starting program:
/Users/bruce/Perl/Parrot/Trip_20090429/rakudo/parrot/parrot_config --dump
Reading symbols for shared libraries .+.........+.+ done
-falign-functions=16 => '1'
-funit-at-a-time => '1'
-fvisibility=hidden => '1'
-maccumulate-outgoing-args => '1'
-W => '1'
-Waggregate-return => '1'
-Wall => '1'
-Wbad-function-cast => '1'
-Wc++-compat => '0'
-Wcast-align => '1'
-Wcast-qual => '1'
-Wchar-subscripts => '1'
Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_PROTECTION_FAILURE at address: 0x00000001
0x01085adf in Parrot_gc_mark_PObj_alive (interp=0x500d70, obj=0xbffff570)
at src/gc/api.c:137
137 else if (p->pmc_ext && PMC_metadata(p))
(gdb) bt
#0 0x01085adf in Parrot_gc_mark_PObj_alive (interp=0x500d70,
obj=0xbffff570) at src/gc/api.c:137
#1 0x010f4b13 in mark_context (interp=0x500d70, ctx=0x518e20) at
src/sub.c:124
#2 0x011a0700 in Parrot_Continuation_mark (interp=0x500d70, pmc=0x4e00c0)
at ./src/pmc/continuation.pmc:92
#3 0x0108c8c0 in mark_special (interp=0x500d70, obj=0x4e00c0) at
src/gc/mark_sweep.c:394
#4 0x01085aa3 in Parrot_gc_mark_PObj_alive (interp=0x500d70,
obj=0x4e00c0) at src/gc/api.c:134
#5 0x010f49e1 in mark_context (interp=0x500d70, ctx=0x518fa0) at
src/sub.c:91
#6 0x011a0700 in Parrot_Continuation_mark (interp=0x500d70, pmc=0x4e0078)
at ./src/pmc/continuation.pmc:92
#7 0x0108c8c0 in mark_special (interp=0x500d70, obj=0x4e0078) at
src/gc/mark_sweep.c:394
#8 0x01085aa3 in Parrot_gc_mark_PObj_alive (interp=0x500d70,
obj=0x4e0078) at src/gc/api.c:134
#9 0x010f49e1 in mark_context (interp=0x500d70, ctx=0x519090) at
src/sub.c:91
#10 0x011a0700 in Parrot_Continuation_mark (interp=0x500d70, pmc=0x4e0048)
at ./src/pmc/continuation.pmc:92
#11 0x0108c8c0 in mark_special (interp=0x500d70, obj=0x4e0048) at
src/gc/mark_sweep.c:394
#12 0x01085aa3 in Parrot_gc_mark_PObj_alive (interp=0x500d70,
obj=0x4e0048) at src/gc/api.c:134
#13 0x010f49e1 in mark_context (interp=0x500d70, ctx=0x519160) at
src/sub.c:91
#14 0x011a0700 in Parrot_Continuation_mark (interp=0x500d70, pmc=0x4e0000)
at ./src/pmc/continuation.pmc:92
#15 0x0108c8c0 in mark_special (interp=0x500d70, obj=0x4e0000) at
src/gc/mark_sweep.c:394
#16 0x01085aa3 in Parrot_gc_mark_PObj_alive (interp=0x500d70,
obj=0x4e0000) at src/gc/api.c:134
#17 0x010f49e1 in mark_context (interp=0x500d70, ctx=0x519260) at
src/sub.c:91
#18 0x0108d0bb in Parrot_gc_trace_root (interp=0x500d70,
trace=GC_TRACE_FULL) at src/gc/mark_sweep.c:129
#19 0x010893a2 in gc_ms_trace_active_PMCs (interp=0x500d70,
trace=GC_TRACE_FULL) at src/gc/gc_ms.c:285
#20 0x010894d4 in gc_ms_mark_and_sweep (interp=0x500d70, flags=1) at
src/gc/gc_ms.c:206
#21 0x01086c12 in Parrot_gc_mark_and_sweep (interp=0x500d70, flags=1) at
src/gc/api.c:717
#22 0x010897a6 in gc_ms_more_traceable_objects (interp=0x500d70,
pool=0x501160) at src/gc/gc_ms.c:373
#23 0x01089904 in gc_ms_get_free_object (interp=0x500d70, pool=0x501160)
at src/gc/gc_ms.c:436
#24 0x010862bc in Parrot_gc_new_pmc_header (interp=0x500d70, flags=1024)
at src/gc/api.c:230
#25 0x010eb04c in get_new_pmc_header (interp=0x500d70, base_type=25,
flags=1024) at src/pmc.c:295
#26 0x010eb157 in pmc_new (interp=0x500d70, base_type=25) at src/pmc.c:108
#27 0x011f8e16 in Parrot_FileHandle_nci_is_closed (interp=0x500d70,
pmc=0xf9f68) at
/Users/bruce/Perl/Parrot/Trip_20090429/rakudo/parrot/tools/build/../../lib/Parrot/Pmc2c/PCCMETHOD.pm:425
#28 0x011a39de in Parrot_NCI_invoke (interp=0x500d70, pmc=0xf9f68,
next=0x0) at ./src/pmc/nci.pmc:335
#29 0x01098109 in Parrot_PCCINVOKE (interp=0x500d70, pmc=0x4e6258,
method_name=0x20028a8, signature=0x128f260 "->I") at src/call/pcc.c:2870
#30 0x0117e9f5 in Parrot_io_is_closed (interp=0x500d70, pmc=0x4e6258) at
src/io/api.c:222
#31 0x011831e2 in Parrot_io_flush_filehandle (interp=0x500d70,
pmc=0x4e6258) at src/io/filehandle.c:738
#32 0x011fa61e in Parrot_FileHandle_nci_flush (interp=0x500d70,
pmc=0xf9ef0) at ./src/pmc/filehandle.pmc:465
#33 0x011a39de in Parrot_NCI_invoke (interp=0x500d70, pmc=0xf9ef0,
next=0x0) at ./src/pmc/nci.pmc:335
#34 0x01098109 in Parrot_PCCINVOKE (interp=0x500d70, pmc=0x4e6258,
method_name=0x2002884, signature=0x128f264 "->") at src/call/pcc.c:2870
#35 0x0117eab5 in Parrot_io_flush (interp=0x500d70, pmc=0x4e6258) at
src/io/api.c:245
#36 0x01180fb5 in Parrot_io_write_buffer (interp=0x500d70,
filehandle=0x4e6258, s=0xbffff570) at src/io/buffer.c:626
#37 0x011fad00 in Parrot_FileHandle_nci_puts (interp=0x500d70,
pmc=0xf9ec0) at ./src/pmc/filehandle.pmc:518
#38 0x011a39de in Parrot_NCI_invoke (interp=0x500d70, pmc=0xf9ec0,
next=0x0) at ./src/pmc/nci.pmc:335
#39 0x01098109 in Parrot_PCCINVOKE (interp=0x500d70, pmc=0x4e6258,
method_name=0x20027f4, signature=0x128e004 "S->I") at src/call/pcc.c:2870
#40 0x0117ece8 in Parrot_io_putps (interp=0x500d70, pmc=0x4e6258,
s=0xbffff570) at src/io/api.c:474
#41 0x0117edef in Parrot_io_write (interp=0x500d70, pmc=0x4e6258,
buffer=0x127b588, length=1) at src/io/api.c:327
#42 0x0117f1f1 in Parrot_io_puts (interp=0x500d70, pmc=0x4e6258,
s=0x127b588 "\n") at src/io/api.c:449
#43 0x0101fa8f in Parrot_say_sc (cur_opcode=0x5181bc, interp=0x500d70) at
src/ops/io.ops:238
#44 0x010edea3 in runops_slow_core (interp=0x500d70, pc=0x5181bc) at
src/runcore/cores.c:462
#45 0x010ed0a5 in runops_int (interp=0x500d70, offset=3) at
src/runcore/main.c:981
#46 0x0109ab31 in runops (interp=0x500d70, offs=3) at src/call/ops.c:107
#47 0x0109adf7 in runops_args (interp=0x500d70, sub=0x4e5fb8,
obj=0x20352e0, meth_unused=0x0, sig=0x127a32c "vP", ap=0xbffff79c "?_N")
at src/call/ops.c:256
#48 0x0109bc39 in Parrot_runops_fromc_args (interp=0x500d70, sub=0x4e5fb8,
sig=0x127a32c "vP") at src/call/ops.c:325
#49 0x010788be in Parrot_runcode (interp=0x500d70, argc=2,
argv=0xbffff870) at src/embed.c:1009
#50 0x00002270 in main (argc=2, argv=0xbffff870) at parrot_config.c:96
(gdb) l
132
133 if (PObj_is_special_PMC_TEST(obj))
134 mark_special(interp, p);
135
136 # ifndef NDEBUG
137 else if (p->pmc_ext && PMC_metadata(p))
138 fprintf(stderr, "GC: error obj %p (%s) has
properties\n",
139 (void *)p,
(char*)p->vtable->whoami->strstart);
140 # endif
141 }
(gdb)
}}}
= OTHER REPORTS =
* 2009-05-26, in email to perl6-users, Nelo Onyiah reported the issue.
* 2009-05-28, in #perl6, ZuLuuuuuu reported the issue on Ubuntu 9.04. I
assume his rev was r39025, since it was the PARROT_REVISION in Rakudo at
the time. He also reported that the problem was resolved in r39219.
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/717>
Parrot <https://trac.parrot.org/parrot/>
Parrot Development
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