Comment # 29 on bug 935086 from Uwe Geuder

Created attachment 639442 [details]
screen picture of a successful resume (rd.break=pre-mount) during my last sleep

>From the picture we see that after reporting the compresssion ratio there will
be 2 lines of size information of the compressed image. 

When the hang occurs only 0 or 1 line of compressed image statistics is written
and then the system hangs (as shown in previous attachments 639392 and 639393)
If you look at code starting from line 669 in load.c you see that it does
nothing besides printf() http://paste.opensuse.org/45471188
That really would look like printf() is hanging, but I cannot believe that. On
one side it could vaguely explain why rd.break=pre-mount makes a difference,
the console can be in different state after having been in an interactive shell
just before. But in the normal setup stdout of the resume process is not the
console at all, it's the socket to journald. And the hang has been reproducible
with the socket and with the console. So no, hanging in printf() makes no sense
to me. 

My printf debugging occurs even later, so we are not even close to the place
where the kernel switches to the structures restored from snapshot. The hang
seems to occur while the resume process runs in user space or does trivial
printf() at most. Of course getting a call stack of the resume process might be
helpful.