Thanks, we’ll look into it. We try to avoid malloc(0) because it’s not portable, but it sometimes slips through. https://trac.mpich.org/projects/mpich/ticket/2054 We also have our internal memory tracing integrated into MPICH, that is tested regularly. We should probably also update it to check for zero-byte allocation errors. — Pavan On Mar 7, 2014, at 2:45 AM, Matthieu Dorier <[email protected]> wrote:

Hi,

I wanted to debug a memory corruption in an MPI program using the electric-fence tool, and noticed that electric-fence detects an error already in MPI_Init (thus the program stops and I cannot debug the actual memory corruption that happens later). The following program is a minimal one to exemplify the error:

#include <mpi.h> int main(int argc, char** argv) { MPI_Init(&argc,&argv); MPI_Finalize(); return 0; }

The error output by electric-fence:

ElectricFence Aborting: Allocating 0 bytes, probably a bug.

And the backtrace output by gdb:

Program received signal SIGILL, Illegal instruction. 0x0012d422 in __kernel_vsyscall () (gdb) backtrace #0 0x0012d422 in __kernel_vsyscall () #1 0x0040c976 in kill () at ../sysdeps/unix/syscall-template.S:82 #2 0x0012fc54 in EF_Abort () from /usr/lib/libefence.so.0 #3 0x0012f71b in memalign () from /usr/lib/libefence.so.0 #4 0x0012f88b in malloc () from /usr/lib/libefence.so.0 #5 0x001e3b6b in MPID_nem_init () from /home/mdorier/deploy/lib/libmpich.so.10 #6 0x001d2f4c in MPIDI_CH3_Init () from /home/mdorier/deploy/lib/libmpich.so.10 #7 0x001c8c57 in MPID_Init () from /home/mdorier/deploy/lib/libmpich.so.10 #8 0x0029d435 in MPIR_Init_thread () from /home/mdorier/deploy/lib/libmpich.so.10 #9 0x0029cd33 in PMPI_Init () from /home/mdorier/deploy/lib/libmpich.so.10 #10 0x0804859f in main (argc=1, argv=0xbffff994) at m.c:4

The version of mpich is 3.0.4, gcc 4.6.4, on Ubuntu 10.4, linux kernel 2.6.32.

I suspect a call to malloc with 0 as parameter, whose output is properly checked by Mpich, but makes electric-fence think there is an error.

Matthieu Dorier PhD student at ENS Rennes http://people.irisa.fr/Matthieu.Dorier _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss