Description of problem:

Starting with kernel 2.6.26, "strace -f" fails to trace child processes. 

Version-Release number of selected component (if applicable):

It worked in kernel-2.6.25.14-69.fc8, and has been failing since kernel-2.6.26.3-14.fc8

How reproducible:

Very


Steps to Reproduce:

Use a simple test program, like bug.c:

  #include <stdio.h>
  main()
  {
        if ( fork() ) {
                printf("parent\n");
        } else {
                printf("child\n");
        }
  }


Then run
 
  strace -f -o strace.out ./bug


Actual results:

An error message is printed, and the child process write() does not appear
in the strace log.   Strangely, I've seen different error messages on different Fedora 8 systems, either:

  PANIC: attached pid 26968 exited
or
  resume: ptrace(PTRACE_SYSCALL, ...): No such process
  

Expected results:

  No error message is printed, and the write("child") appears in the 
  strace.out file


Additional info:

Even though the error comes from strace, I'm assuming that it's actually a problem with the kernel, because reverting to an earlier kernel version causes the problem to go away.

I'm seeing the problem in both Fedora 8 and Fedora 9, and in both cases it starts showing up in the 2.6.26.* kernels