Comment # 17 on bug 935086 from Takashi Iwai

(In reply to Uwe Geuder from comment #14)
> (In reply to Takashi Iwai from comment #13)
> 
> > Could you try one more test?
> 
> No problem, I'm glad to getting this solved.
> 
> > Please reinstall suspend and pm-utils but
> > change SLEEP_MODULE to "kernel" in pm-utils default.  Does this make resume
> > working again?
> 
> Just to clarify: Removing pm-utils was something I tried without success in
> a previous installation of 13.2. For the whole lifetime of this report
> pm-utils has always been installed.
> 
> I re-installed the suspend package and created a configuration file like
> this:
> 
> $ cat /etc/pm/config.d/sleepmodule.config 
> SLEEP_MODULE="kernel"
> 
> Resume works without hanging. The suspend hooks are executed as shown in the
> attached log file. E.g. grubonce suppresses the usual grub menu when waking
> up
> from hibernation. That suppression was not there while suspend package was
> uninstalled. 
> 
> However, I notice the following issues
> 
> 1. I made 5 hibernate cycles. In one of the 5 the machine crashed and
> rebooted
> during the resume. Obviously at the reboot no valid snapshot was found
> anymore, so a fresh boot occurred. No traces where left in the logs what has
> happened. So it probably happened shortly before, during, or short after
> switching to the real root file system and no information could be stored to
> the filesystem.
> I don't have time now to make more reliable statistics how often that really
> happens. But while using the rd.break-premount work-around it has not
> happened during ~3 months, some 50-100 resumes.

Hmm, I can't think of the relation with pm-utils immediately.  (Actually not
figured out why user-suspend got broken but kernel-suspend works.)

All things look like a side effect of racy resume procedure to me, so I won't
be surprised if some instability remains even without pm-utils.

> 2. There is no plymouth screen during hibernation. Instead there is
> flickering and console messages are visible. As said before, not a
> showstopper for me, but a regression from 13.1

This is a known drawback of kernel-suspend, IIRC.