Looks like this is nothing to do with cargo directly, just running rustc
on my box hangs:
futex(0x7f8a97aa180c, FUTEX_WAKE_PRIVATE, 2147483647) = 0
futex(0x7f8a97aa1818, FUTEX_WAKE_PRIVATE, 2147483647) = 0
rt_sigaction(SIGPIPE, {SIG_IGN, [PIPE], SA_RESTORER|SA_RESTART, 0x7f8a9def34b0}, {SIG_DFL, [], 0}, 8) = 0
open("/proc/self/maps", O_RDONLY|O_CLOEXEC) = 3
getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=RLIM64_INFINITY}) = 0
fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
read(3, "55beef2d1000-55beef2d3000 r-xp 0"..., 1024) = 1024
read(3, " /usr/local/lib/libaren"..., 1024) = 1024
read(3, "94a1c000-7f8a94a1d000 r--p 00043"..., 1024) = 1024
read(3, "0d7dc60162.so\n7f8a97a3a000-7f8a9"..., 1024) = 1024
read(3, "/lib/x86_64-linux-gnu/librt-2.23"..., 1024) = 1024
read(3, ".so\n7f8a98331000-7f8a98530000 --"..., 1024) = 1024
read(3, "01 2364537 /u"..., 1024) = 1024
read(3, " /usr/local/lib/"..., 1024) = 1024
read(3, "1ec8.so\n7f8a996af000-7f8a996b100"..., 1024) = 1024
read(3, "-p 00051000 08:01 2364547 "..., 1024) = 1024
read(3, "8ae8f9c9152b9183.so\n7f8a9ac62000"..., 1024) = 1024
read(3, ".so\n7f8a9b10f000-7f8a9b110000 rw"..., 1024) = 1024
read(3, "000-7f8a9b5a1000 rw-p 0001e000 0"..., 1024) = 1024
read(3, " /usr/local/li"..., 1024) = 1024
read(3, "brustc_metadata-1b4e3bb15c9d6681"..., 1024) = 1024
read(3, "5b79e143c2b1.so\n7f8a9c9d0000-7f8"..., 1024) = 1024
read(3, "7f8a9d3d1000-7f8a9d3d2000 rw-p 0"..., 1024) = 1024
read(3, "l/lib/librustc_save_analysis-5af"..., 1024) = 1024
read(3, "8a9debe000 rw-p 00000000 00:00 0"..., 1024) = 1024
read(3, "7f8a9e5db000-7f8a9e840000 r-xp 0"..., 1024) = 1024
read(3, "8a9eca7000 r-xp 00000000 08:01 1"..., 1024) = 775
close(3) = 0
sched_getaffinity(24497, 32, [f, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]) = 32
rt_sigaction(SIGSEGV, {0x7f8a9e30e8e0, [], SA_RESTORER|SA_STACK|SA_SIGINFO, 0x7f8a9def34b0}, NULL, 8) = 0
rt_sigaction(SIGBUS, {0x7f8a9e30e8e0, [], SA_RESTORER|SA_STACK|SA_SIGINFO, 0x7f8a9def34b0}, NULL, 8) = 0
sigaltstack(NULL, {ss_sp=NULL, ss_flags=SS_DISABLE, ss_size=0}) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f8a9eea1000
sigaltstack({ss_sp=0x7f8a9eea1000, ss_flags=0, ss_size=8192}, NULL) = 0
futex(0x7f8a93800a40, FUTEX_WAIT_PRIVATE, 2, NULL) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
--- SIGWINCH {si_signo=SIGWINCH, si_code=SI_KERNEL} ---
futex(0x7f8a93800a40, FUTEX_WAIT_PRIVATE, 2, NULL
[STUCK]