Maybe if some one could see something from strace output:
...
writev(2, [{iov_base="mdadm: /dev/sdb1 is identified a"..., iov_len=64}, {iov_base=NULL, iov_len=0}], 2mdadm: /dev/sdb1 is identified as a member of /dev/md1, slot 1.
) = 64
open("/dev/sda1", O_RDWR|O_EXCL|O_DIRECT|O_LARGEFILE) = 5
ioctl(5, BLKSSZGET, [512]) = 0
fstat64(5, {st_mode=S_IFBLK|0600, st_rdev=makedev(8, 1), ...}) = 0
ioctl(5, BLKGETSIZE64, [2199023255552]) = 0
_llseek(5, 4096, [4096], SEEK_SET) = 0
read(5, "\374N+\251\1\0\0\0\1\0\0\0\0\0\0\0\200\376{a<qqX\367\314@B\221v@\202"..., 4096) = 4096
_llseek(5, 0, [8192], SEEK_CUR) = 0
_llseek(5, 8192, [8192], SEEK_SET) = 0
read(5, "bitm\4\0\0\0\200\376{a<qqX\367\314@B\221v@\202\375q\0\0\0\0\0\0"..., 512) = 512
_llseek(5, 0, [8704], SEEK_CUR) = 0
fstat64(5, {st_mode=S_IFBLK|0600, st_rdev=makedev(8, 1), ...}) = 0
close(5) = 0
writev(2, [{iov_base="mdadm: /dev/sda1 is identified a"..., iov_len=64}, {iov_base=NULL, iov_len=0}], 2mdadm: /dev/sda1 is identified as a member of /dev/md1, slot 0.
) = 64
open("/dev/sda1", O_RDONLY|O_EXCL|O_DIRECT|O_LARGEFILE) = 5
ioctl(5, BLKSSZGET, [512]) = 0
fstat64(5, {st_mode=S_IFBLK|0600, st_rdev=makedev(8, 1), ...}) = 0
ioctl(5, BLKGETSIZE64, [2199023255552]) = 0
_llseek(5, 4096, [4096], SEEK_SET) = 0
read(5, "\374N+\251\1\0\0\0\1\0\0\0\0\0\0\0\200\376{a<qqX\367\314@B\221v@\202"..., 4096) = 4096
_llseek(5, 0, [8192], SEEK_CUR) = 0
_llseek(5, 8192, [8192], SEEK_SET) = 0
read(5, "bitm\4\0\0\0\200\376{a<qqX\367\314@B\221v@\202\375q\0\0\0\0\0\0"..., 512) = 512
_llseek(5, 0, [8704], SEEK_CUR) = 0
close(5) = 0
ioctl(4, RAID_VERSION, 0xbebf11ac) = 0
fstat64(4, {st_mode=S_IFBLK|0600, st_rdev=makedev(9, 1), ...}) = 0
readlink("/sys/dev/block/9:1", "../../devices/virtual/block/md1", 199) = 31
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x1521ea4} ---
+++ killed by SIGSEGV +++
Segmentation fault