Stacktrace umount -f

execve("/bin/umount", ["umount", "-f", "/srv/bind-target/sub1"], [/* 18 vars */]) = 0
brk(0)                                  = 0x405df00
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7257d20b0000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=13045, ...}) = 0
mmap(NULL, 13045, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7257d20ac000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libblkid.so.1", O_RDONLY)    = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\220^\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=128256, ...}) = 0
mmap(NULL, 2223432, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7257d1c77000
mprotect(0x7257d1c93000, 2097152, PROT_NONE) = 0
mmap(0x7257d1e93000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c000) = 0x7257d1e93000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libuuid.so.1", O_RDONLY)     = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360\25\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=15720, ...}) = 0
mmap(NULL, 2110736, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7257d1a73000
mprotect(0x7257d1a77000, 2093056, PROT_NONE) = 0
mmap(0x7257d1c76000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3000) = 0x7257d1c76000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\355\1\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1437064, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7257d20ab000
mmap(NULL, 3545160, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7257d1711000
mprotect(0x7257d186a000, 2093056, PROT_NONE) = 0
mmap(0x7257d1a69000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x158000) = 0x7257d1a69000
mmap(0x7257d1a6e000, 18504, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7257d1a6e000
close(3)                                = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7257d20a9000
arch_prctl(ARCH_SET_FS, 0x7257d20a9740) = 0
mprotect(0x7257d1a69000, 16384, PROT_READ) = 0
mprotect(0x7257d20b3000, 4096, PROT_READ) = 0
munmap(0x7257d20ac000, 13045)           = 0
brk(0)                                  = 0x405df00
brk(0x407ef00)                          = 0x407ef00
brk(0x407f000)                          = 0x407f000
open("/usr/lib/locale/locale-archive", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=2951392, ...}) = 0
mmap(NULL, 2951392, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7257d1440000
close(3)                                = 0
umask(022)                              = 022
getuid()                                = 0
geteuid()                               = 0
readlink("/srv", 0x7993be0f9b40, 4096)  = -1 EINVAL (Invalid argument)
readlink("/srv/bind-target", 0x7993be0f9b40, 4096) = -1 EINVAL (Invalid argument)
readlink("/srv/bind-target/sub1", 0x7993be0f9b40, 4096) = -1 ESTALE (Stale NFS file handle)
umask(077)                              = 022
open("/etc/mtab", O_RDONLY)             = 3
umask(022)                              = 077
fstat(3, {st_mode=S_IFREG|0644, st_size=670, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7257d20af000
read(3, "/dev/sda1 / ext3 rw,errors=remou"..., 4096) = 670
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0x7257d20af000, 4096)            = 0
umount("/srv/bind-target/sub1", MNT_FORCE) = -1 ESTALE (Stale NFS file handle)
dup(2)                                  = 3
fcntl(3, F_GETFL)                       = 0x8002 (flags O_RDWR|O_LARGEFILE)
fstat(3, {st_mode=S_IFCHR|0600, st_rdev=makedev(136, 0), ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7257d20af000
lseek(3, 0, SEEK_CUR)                   = -1 ESPIPE (Illegal seek)
open("/usr/share/locale/locale.alias", O_RDONLY) = 4
fstat(4, {st_mode=S_IFREG|0644, st_size=2570, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7257d20ae000
read(4, "# Locale name alias data base.\n#"..., 4096) = 2570
read(4, "", 4096)                       = 0
close(4)                                = 0
munmap(0x7257d20ae000, 4096)            = 0
open("/usr/share/locale/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
write(3, "umount2: Stale NFS file handle\n", 31umount2: Stale NFS file handle
) = 31
close(3)                                = 0
munmap(0x7257d20af000, 4096)            = 0
open("/usr/share/locale/en_US/LC_MESSAGES/util-linux-ng.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/util-linux-ng.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
write(2, "umount: /srv/bind-target/sub1: S"..., 52umount: /srv/bind-target/sub1: Stale NFS file handle) = 52
write(2, "\n", 1
)                       = 1
umount("/srv/bind-target/sub1", MNT_FORCE) = -1 ESTALE (Stale NFS file handle)
write(2, "umount2: Stale NFS file handle\n", 31umount2: Stale NFS file handle
) = 31
exit_group(1)                           = ?