# gdb --args umount -f -r -d /mnt/autofs/
GNU gdb (GDB) 7.1-ubuntu
Copyright (C) 2010 Free Software Foundation, Inc.
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Reading symbols from /bin/umount...(no debugging symbols found)...done.
(gdb) run
Starting program: /bin/umount -f -r -d /mnt/autofs/
umount2: Device or resource busy
umount: /mnt/autofs/ busy - remounted read-only

Program received signal SIGSEGV, Segmentation fault.
__strlen_sse2 () at ../sysdeps/x86_64/multiarch/../strlen.S:31
31	../sysdeps/x86_64/multiarch/../strlen.S: No such file or directory.
	in ../sysdeps/x86_64/multiarch/../strlen.S
(gdb) bt
#0  __strlen_sse2 () at ../sysdeps/x86_64/multiarch/../strlen.S:31
#1  0x0000000000405cc9 in ?? ()
#2  0x0000000000405d9e in ?? ()
#3  0x0000000000405373 in ?? ()
#4  0x00000000004032fb in ?? ()
#5  0x0000000000403b72 in ?? ()
#6  0x00007f2ed0b1ec4d in __libc_start_main (main=<value optimized out>, 
    argc=<value optimized out>, ubp_av=<value optimized out>, 
    init=<value optimized out>, fini=<value optimized out>, 
    rtld_fini=<value optimized out>, stack_end=0x7fff5e86dfe8)
    at libc-start.c:226
#7  0x0000000000402939 in ?? ()
#8  0x00007fff5e86dfe8 in ?? ()
#9  0x000000000000001c in ?? ()
#10 0x0000000000000005 in ?? ()
#11 0x00007fff5e86e945 in ?? ()
#12 0x00007fff5e86e951 in ?? ()
#13 0x00007fff5e86e954 in ?? ()
#14 0x00007fff5e86e957 in ?? ()
#15 0x00007fff5e86e95a in ?? ()
#16 0x0000000000000000 in ?? ()
(gdb)