[Bug libgomp/28468] New: OpenMP-parallelized program crashes when OMP_NUM_THREADS > 1

[Bug libgomp/28468] New: OpenMP-parallelized program crashes when OMP_NUM_THREADS > 1

[bruno at clisp dot org]

Versions:
* gcc: gcc (GCC) 4.2.0 20060715 (experimental)
* cpu: AMD-K7 (i686)
* kernel: Linux 2.4.21-99 (SuSE 9.0)
* glibc: glibc-2.3.6 built with LinuxThreads, _not_ NPTL

Test program:
============================== omp-test1.c =======================
#include <stdlib.h>
#include <stdio.h>

/* A computational task whose duration depends on x.  */
int job (int x)
{
  int j = rand() % (100 + 10 * x);
  int i;

  for (i = j - 1; i > 0; i--)
    if (j % i == 0)
      break;

  return i;
}

int main (int argc, char *argv[])
{
  int n = 10000;

  int *mem = malloc (n * sizeof (int));
  int i;

  /* Because the tasks don't have all the same duration, a dynamic
     schedule is best.  */
  #pragma omp parallel for schedule(dynamic)
  for (i = 0; i < n; i++)
    mem[i] = job (i);

  for (i = 0; i < n; i++)
    printf ("mem[%d] = %d\n", i, mem[i]);

  return 0;
}
=====================================================================

$ gcc -fopenmp -Wall -O omp-test1.c

The single-threaded program runs fine:
$ unset OMP_NUM_THREADS; ./a.out
or
$ export OMP_NUM_THREADS=1; ./a.out

But with more than one thread it crashes:

$ export OMP_NUM_THREADS=2; ./a.out
Segmentation fault (core dumped)
$ gdb a.out core.26661
GNU gdb 6.4
Copyright 2005 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 "i686-pc-linux-gnu"...Using host libthread_db
library "/lib/libthread_db.so.1".

Core was generated by `./a.out'.
Program terminated with signal 11, Segmentation fault.
Reading symbols from
/gfs/ibook/Volumes/ExtData/bin.x86-linux/gnu-inst-gcc/4.2-20060715/lib/gcc/i686-pc-linux-gnu/4.2.0/libgomp.so.1...done.
Loaded symbols for
/packages/gnu-inst-gcc/4.2-20060715/lib/gcc/i686-pc-linux-gnu/4.2.0/libgomp.so.1
Reading symbols from /lib/libpthread.so.0...done.
Loaded symbols for /lib/libpthread.so.0
Reading symbols from /lib/libc.so.6...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/librt.so.1...done.
Loaded symbols for /lib/librt.so.1
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
#0  gomp_iter_dynamic_next (pstart=0xbfffe9c4, pend=0xbfffe9c8)
    at ../../../gcc-4.2-20060715/libgomp/iter.c:189
189       start = ws->next;
(gdb) where
#0  gomp_iter_dynamic_next (pstart=0xbfffe9c4, pend=0xbfffe9c8)
    at ../../../gcc-4.2-20060715/libgomp/iter.c:189
#1  0x4001c8e8 in gomp_loop_dynamic_next (istart=0xbfffe9c4, iend=0xbfffe9c8)
    at ../../../gcc-4.2-20060715/libgomp/loop.c:248
#2  0x080486ed in main.omp_fn.0 ()
#3  0x0804861e in main ()
(gdb) print ws
$1 = (struct gomp_work_share *) 0x0


-- 
           Summary: OpenMP-parallelized program crashes when OMP_NUM_THREADS
                    > 1
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgomp
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bruno at clisp dot org
 GCC build triplet: i686-suse-linux-gnu
  GCC host triplet: i686-suse-linux-gnu
GCC target triplet: i686-suse-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28468

[Bug libgomp/28468] OpenMP-parallelized program crashes when OMP_NUM_THREADS > 1

[bruno at clisp dot org]

------- Comment #1 from bruno at clisp dot org  2006-11-07 14:36 -------
It's still reproducible with gcc-4.2-20061031:

$ export OMP_NUM_THREADS=2
$ gdb a.out 
GNU gdb 6.4
Copyright 2005 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 "i686-pc-linux-gnu"...Using host libthread_db
library "/lib/libthread_db.so.1".

(gdb) run
Starting program: /dev/shm/a.out 
[Thread debugging using libthread_db enabled]
[New Thread 16384 (LWP 4983)]
[New Thread 32769 (LWP 4984)]
[New Thread 16386 (LWP 4985)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 16386 (LWP 4985)]
gomp_iter_dynamic_next (pstart=0xbf7ffa94, pend=0xbf7ffa98) at
../../../gcc-4.2-20061031/libgomp/iter.c:189
189       start = ws->next;
(gdb) where
#0  gomp_iter_dynamic_next (pstart=0xbf7ffa94, pend=0xbf7ffa98) at
../../../gcc-4.2-20061031/libgomp/iter.c:189
#1  0x4001ca78 in gomp_loop_dynamic_next (istart=0xbf7ffa94, iend=0xbf7ffa98)
at ../../../gcc-4.2-20061031/libgomp/loop.c:248
#2  0x080486ed in main.omp_fn.0 ()
#3  0x4001de5d in gomp_thread_start (xdata=0xbfffe580) at
../../../gcc-4.2-20061031/libgomp/team.c:108
#4  0x4003bfe6 in pthread_start_thread (arg=0xbf7ffbe0) at manager.c:310
#5  0x4003c07f in pthread_start_thread_event (arg=0xbf7ffbe0) at manager.c:334
#6  0x4014e0aa in clone () from /lib/libc.so.6


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28468

[Bug libgomp/28468] OpenMP-parallelized program crashes when OMP_NUM_THREADS > 1

[jakub at gcc dot gnu dot org]

------- Comment #2 from jakub at gcc dot gnu dot org  2006-11-15 09:45 -------
Was LinuxThreads built at least --with-tls support or without?
If without and libgomp has been built without --disable-tls and your
assembler/linker support TLS, libgomp might be using __thread eventhough
glibc doesn't support that.
There have been some patches added recently to improve gcc configure checks
for the runtime support of TLS.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28468

[Bug libgomp/28468] OpenMP-parallelized program crashes when OMP_NUM_THREADS > 1

[bruno at clisp dot org]

------- Comment #3 from bruno at clisp dot org  2006-11-15 13:38 -------
> Was LinuxThreads built at least --with-tls support or without?

The glibc was built with LinuxThreads without TLS. (I gave --without-tls
explicitly to the glibc build.)

> If without and libgomp has been built without --disable-tls and your
> assembler/linker support TLS, libgomp might be using __thread eventhough
> glibc doesn't support that.

Yes, this is exactly the problem; see the analysis and patch in
http://gcc.gnu.org/ml/gcc/2006-11/msg00244.html

> There have been some patches added recently to improve gcc configure checks
> for the runtime support of TLS.

The only patch that has been committed is this one from Daniel Jacobowitz
http://gcc.gnu.org/viewcvs/trunk/config/tls.m4?r1=117049&r2=118777
It has no effect on this bug, since it applies only to the cross-compiling
case.

For the native compile, I posted a patch that is known to fix this bug:
http://gcc.gnu.org/ml/gcc/2006-11/msg00244.html
It has been approved by Richard Henderson:
http://gcc.gnu.org/ml/gcc/2006-11/msg00255.html
But noone has committed it to the GCC SVN.

Could someone please commit this patch on the HEAD and possibly on the 4.2
branch? (It is not a regression, if you argue that libgomp and -fopenmp is a
new feature. But it is a regression if you argue that there are packages out
there, such as GNU gettext 0.16, which use -fopenmp if available, and this
bug turns a program that would run unparallelized but correctly with gcc-4.1
into a program that runs parallelized but crashes with gcc-4.2.)


-- 

bruno at clisp dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu dot org
             Status|WAITING                     |UNCONFIRMED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28468

[Bug libgomp/28468] OpenMP-parallelized program crashes when OMP_NUM_THREADS > 1

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2007-02-07 13:35 -------
Subject: Bug 28468

Author: jakub
Date: Wed Feb  7 13:35:17 2007
New Revision: 121689

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=121689
Log:
2007-02-07  Bruno Haible  <bruno@clisp.org>

config/
        PR libgomp/28468
        * config/tls.m4 (GCC_CHECK_TLS): Also check whether the libc supports
        TLS via __thread.

2007-02-07  Jakub Jelinek  <jakub@redhat.com>

{libgomp,libstdc++-v3,libmudflap,libjava}/
        PR libgomp/28468
        * configure: Regenerate.

Modified:
    trunk/config/ChangeLog
    trunk/config/tls.m4
    trunk/libgomp/ChangeLog
    trunk/libgomp/configure
    trunk/libjava/ChangeLog
    trunk/libjava/configure
    trunk/libmudflap/ChangeLog
    trunk/libmudflap/configure
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/configure


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28468

[Bug libgomp/28468] OpenMP-parallelized program crashes when OMP_NUM_THREADS > 1

[jakub at gcc dot gnu dot org]

------- Comment #5 from jakub at gcc dot gnu dot org  2007-02-07 13:39 -------
Approved offline by Alex Oliva, committed so far on the trunk.
Will backport to 4.2 branch after a week or so on the trunk.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28468

[Bug libgomp/28468] OpenMP-parallelized program crashes when OMP_NUM_THREADS > 1

[rth at gcc dot gnu dot org]

------- Comment #6 from rth at gcc dot gnu dot org  2007-10-23 15:40 -------
Did you backport the fix to 4.2?


-- 

rth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jakub at gcc dot gnu dot org
                   |dot org                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28468

[Bug libgomp/28468] OpenMP-parallelized program crashes when OMP_NUM_THREADS > 1

[jakub at gcc dot gnu dot org]

------- Comment #7 from jakub at gcc dot gnu dot org  2008-03-10 16:09 -------
No plaans to backport this to 4.2 anymore.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28468