Bug#827323: linux: Regression v4.5 -> v4.6: system freeze after suspend/resume due to iAMT watchdog

[Sebastian Reichel <sre@debian.org>]

Source: linux
Version: 4.5.5-1
Severity: normal

Hi,

My Lenovo Thinkpad X250 freezes a couple of seconds after
resuming from suspend. This happened with 4.5, but not
with v4.6. I bisected the problem using mainline kernel
with Debian config to the following commit:

sre@earth ~/src/linux (git)-[fdd9b86...|bisect] % git bisect bad
fdd9b8655933c3eb3154fe1ed351c17b654258bd is the first bad commit
commit fdd9b8655933c3eb3154fe1ed351c17b654258bd
Author: Alexander Usyskin <alexander.usyskin@intel.com>
Date:   Fri Jan 8 00:49:21 2016 +0200

    mei: wd: drop the watchdog code from the core mei driver
    
    Instead of integrating the iAMT watchdog in the mei core driver
    we will create a watchdog device on the mei client bus and
    create a driver for it.
    
    This patch removes the watchdog code from the mei core driver.
    
    Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
    Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

My system was configured to use the watchdog via "RuntimeWatchdogSec=30"
in "/etc/systemd/system.conf". After disabling the feature no system
freeze happens after suspend/resume cycle.

-- Sebastian

-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (1000, 'testing'), (500, 'unstable'), (200, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386, armhf

Kernel: Linux 4.6.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)