| Subject: | SIGSEGV when calling sweep() due to PL_compiling.cop_warnings structure changes (?) |
I get SIGSEGV on perl, v5.8.8 built for i486-linux-gnu-thread-multi when
I call Devel::GC::Helper::sweep()
Investigation with debugperl and gdb suggests the segfault happens with
the following call stack:
Program received signal SIGSEGV, Segmentation fault.
0xb7c9218f in gc_note_sv () from
/usr/local/lib/perl/5.8.8/auto/Devel/GC/Helper/Helper.so
(gdb) bt
#0 0xb7c9218f in gc_note_sv () from
/usr/local/lib/perl/5.8.8/auto/Devel/GC/Helper/Helper.so
#1 0xb7c92b2e in sweep_root () from
/usr/local/lib/perl/5.8.8/auto/Devel/GC/Helper/Helper.so
#2 0xb7c94026 in XS_Devel__GC__Helper_sweep ()
from /usr/local/lib/perl/5.8.8/auto/Devel/GC/Helper/Helper.so
#3 0x080f3128 in Perl_pp_entersub (my_perl=0x81b9008) at pp_hot.c:2877
#4 0x080cdd51 in Perl_runops_debug (my_perl=0x81b9008) at dump.c:1459
#5 0x08065ba6 in S_run_body (my_perl=0x81b9008, oldscope=1) at perl.c:2366
#6 0x080655db in perl_run (my_perl=0x81b9008) at perl.c:2283
#7 0x0806013e in main (argc=4, argv=0xbfa77944, env=0xbfa77958) at
perlmain.c:99
Which corresponds to a call to gc_note_sv() from sweep_root() line 243:
243 gc_note_sv(tbl, PL_compiling.cop_warnings);
commenting this line out with /*...*/ and recompiling prevents the
segfault behaviour, but presumably at a cost of some SV leak tracking?
#perl suggests that this is possibly due to PL_compiling.cop_warnings
having changed its structure in 5.8.8 -- what do you think? I don't
track perl changes carefully enough to know for sure.
Here is a patch to work around the behaviour on 5.8.8 (really just to
prevent the segfault):
----------8<----------------------------8<---------------
--- Helper.xs 2006-09-15 00:39:30.000000000 +0100
+++ Helper.xs.old 2006-09-15 00:39:13.000000000 +0100
@@ -240,7 +240,7 @@
ptr_table_store(tbl, &PL_sv_yes, (void*) 1);
gc_note_sv(tbl, PL_compiling.cop_io);
-/* gc_note_sv(tbl, PL_compiling.cop_warnings); */
+ gc_note_sv(tbl, PL_compiling.cop_warnings);
gc_note_sv(tbl, PL_patchlevel);
----------8<----------------------------8<---------------
$ uname -a
Linux wombat 2.6.17.1 #11 Sun Jul 2 02:20:52 BST 2006 i686 GNU/Linux
Tested on the following perl versions:
$ perl -V
Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
Platform:
osname=linux, osvers=2.6.15-1-686, archname=i486-linux-gnu-thread-multi
uname='linux ulises 2.6.15-1-686 #2 mon mar 6 15:27:08 utc 2006 i686
gnulinux '
config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr
-Dprivlib=/usr/share/perl/5.8 -Darchlib=/usr/lib/perl/5.8
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
-Dsitelib=/usr/local/share/perl/5.8.8
-Dsitearch=/usr/local/lib/perl/5.8.8 -Dman1dir=/usr/share/man/man1
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
-Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl
-Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Uusenm
-Duseshrplib -Dlibperl=libperl.so.5.8.8 -Dd_dosuid -des'
hint=recommended, useposix=true, d_sigaction=define
usethreads=define use5005threads=undef useithreads=define
usemultiplicity=define
useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
-DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN
-fno-strict-aliasing -pipe -I/usr/local/include'
ccversion='', gccversion='4.1.2 20060729 (prerelease) (Debian
4.1.1-10)', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
perllibs=-ldl -lm -lpthread -lc -lcrypt
libc=/lib/libc-2.3.6.so, so=so, useshrplib=true,
libperl=libperl.so.5.8.8
gnulibc_version='2.3.6'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
Characteristics of this binary (from libperl):
Compile-time options: MULTIPLICITY PERL_IMPLICIT_CONTEXT
PERL_MALLOC_WRAP THREADS_HAVE_PIDS USE_ITHREADS
USE_LARGE_FILES USE_PERLIO USE_REENTRANT_API
Built under linux
Compiled at Aug 6 2006 15:35:16
@INC:
/etc/perl
/usr/local/lib/perl/5.8.8
/usr/local/share/perl/5.8.8
/usr/lib/perl5
/usr/share/perl5
/usr/lib/perl/5.8
/usr/share/perl/5.8
/usr/local/lib/site_perl
.
$ debugperl -V
Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
Platform:
osname=linux, osvers=2.6.15-1-686, archname=i486-linux-gnu-thread-multi
uname='linux ulises 2.6.15-1-686 #2 mon mar 6 15:27:08 utc 2006 i686
gnulinux '
config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr
-Dprivlib=/usr/share/perl/5.8 -Darchlib=/usr/lib/perl/5.8
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
-Dsitelib=/usr/local/share/perl/5.8.8
-Dsitearch=/usr/local/lib/perl/5.8.8 -Dman1dir=/usr/share/man/man1
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
-Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl
-Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Uusenm
-Duseshrplib -Dlibperl=libperl.so.5.8.8 -Dd_dosuid -des'
hint=recommended, useposix=true, d_sigaction=define
usethreads=define use5005threads=undef useithreads=define
usemultiplicity=define
useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
-DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN
-fno-strict-aliasing -pipe -I/usr/local/include'
ccversion='', gccversion='4.1.2 20060729 (prerelease) (Debian
4.1.1-10)', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
perllibs=-ldl -lm -lpthread -lc -lcrypt
libc=/lib/libc-2.3.6.so, so=so, useshrplib=true,
libperl=libperl.so.5.8.8
gnulibc_version='2.3.6'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
Characteristics of this binary (from libperl):
Compile-time options: DEBUGGING MULTIPLICITY PERL_IMPLICIT_CONTEXT
PERL_MALLOC_WRAP THREADS_HAVE_PIDS USE_ITHREADS
USE_LARGE_FILES USE_PERLIO USE_REENTRANT_API
Built under linux
Compiled at Aug 6 2006 15:46:43
@INC:
/etc/perl
/usr/local/lib/perl/5.8.8
/usr/local/share/perl/5.8.8
/usr/lib/perl5
/usr/share/perl5
/usr/lib/perl/5.8
/usr/share/perl/5.8
/usr/local/lib/site_perl
.