[systemd-devel] Cannot start service due to 'systemd-tty-ask-password-agent --watch' not answering

[Yeela Kaplan]

Hi all,
We have run into a problem starting a service on EL7.1.
We installed the same environment on two hosts, on the first one the service started successfully and on the second one it failed to start.

On the machine failing when running:
systemctl start supervdsmd.service

we see that a child process `systemd-tty-ask-password-agent --watch`
is spawned by systemctl:
 
[root at green-vdsc ~]# pstree -p $$
bash(13179)─┬─pstree(13494)
            └─systemctl(13440)───systemd-tty-ask(13441)

using strace -f we see that systemctl is waiting on a response from systemd-tty-ask but never receives it and gets stuck forever polling:

[pid 14884] execve("/usr/bin/systemd-tty-ask-password-agent", ["/usr/bin/systemd-tty-ask-passwor"..., "--watch"], [/* 31 vars */]) = 0
.
.
.
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "\242\233\270\f9\257\326\257_\n\30\264\263\17\32\272\0058\331\245\236f\207\202\321(\322`pS\324\376"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "G\262_$\210%*\275Q`G\240\361F\323\306\254.\334\323]\314:!u\343H\200\227\1\206&"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "\272\177J\330D\252\367\2\367w\302\230-\221'\267\365\376\214\217\334\327\245a\311\377\tfc\177\273j"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "\324\230x\231\222\210\271-\22a\2134\202\274\\\373\305\231;\177\244e\246=k\204\216\327\340iG\17"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "3\210\234X\0N\202G\354\22WFt^\331V\344\32\\A\36\323[\302\370\363\371\210\211\t\2129"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "+\235\26\274\373R\34\377Rs9\370\273\370\t),V\276\v`\233^E\256\257lX#\27\23W"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "\346\237\ru5\311\372\362K?2\203\300\246C2K(\4+\20\341t\4S\370\35\25}>\265\240"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "F\25\257j\233q\315W\25\334\306\233\217!\306$\255Y\33\364\0039Qy\2\223 at o\235\257hw"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "\324\316\10k*\332A\253\344^\5y\372\10I\375\216\372\271\277\205\2264\0\35>?]`\263\374\275"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "\34P\10w\314e\270\226X\t\212\30\"\17.\334\3471\342B\334\272\315\351\367\324k\273S\363\323f"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "\210\230;\227\31\261\364A\301#\374\311\206?\17\202\2749\340\246\323gm\315\325\361\335K\200\6h\275"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])
read(3, "i\10Dl\5\312\222\376\10l\37\277X\341CIs\\\"\235{\315|\334\227\10>\246a\5,\36"..., 120) = 120
poll([{fd=3, events=POLLIN}], 1, 100)   = 1 ([{fd=3, revents=POLLIN}])


systemctl is waiting for a response from its child process forever and does not close it. 
As a result, it never even tries to run the start command for our service supervdsm.
So it looks like an issue either with systemd or the way our service interacts with systemd.

Is anyone familiar with such an issue or has an idea why it happens and how to fix it? 



We still have the machine with this problem running if it helps,
can anybody maybe take a look and help figure out what's the problem?

Thanks,
Yeela.