Re: [BUG] 3.10 regression: hang on suspend

[Stanislaw Gruszka <sgruszka@redhat.com>]

On Tue, Jul 16, 2013 at 08:23:33PM +0200, Ortwin Glück wrote:
> Without NetworkManager, no X, on console and with plain jane wpa_supplicant I do
> echo mem > /sys/power state
> 
> After that, it still responds to keyboard events: I can switch VT
> and type on the consoles, but I can not login on a different VT
> (pressing Enter after the username doesn't return). So I guess tasks
> have been frozen, but it hangs in stopping devices.
> 
> settings for pm_test:
> devices: same behviour as above
> freezer: works as expected (stops tasks; sleeps; resumes tasks)
> 
> Nothing in the logs. How can I enable more log?

This looks like livelock, i.e. kernel wait for mutex to be released
but that never happen , for example because of deadlock. Enabling 
CONFIG_LOCKDEP=y could help to diagnose this. Other than that
sysreq key w (show blocked task) could help, see
Documentation/sysrq.txt for instructions how to use this key.
Also please remember set no_console_suspend boot option to
allow print messages on tty during suspend.

Stanislaw