[SRU][Bionic][PATCH 0/1] Fixes for LP1800849 [v2]

[Frank Heimes]

BugLink: http://bugs.launchpad.net/bugs/1800849

== SRU Justification ==

Description: kvm: fix deadlock when killed by oom
Symptom: oom killer leaves processes in a deadlock state.
Problem: The problem arises in the rare cases in which
         handle_mm_fault does not release the mm_sem.
Solution: Correct the issue by manually release the mm_sem when needed.

== Fix ==

306d6c49ac9ded11114cb53b0925da52f2c2ada1 ("s390/kvm: fix deadlock when
killed by oom")

== Regression Potential ==

Low and minimal, because:
- s390x only
- limited to one single file: /arch/s390/mm/fault.c
- just two additional lines added (if stmt)
- Xenial and Cosmic already have this commit via upstream stable updates.
- Hence patch is just missing in Bionic.
- Test kernel was build for testting.

== Test Case ==

Create numerous KVM guests so that the host starts swapping
and memory becomes overcomitted and the oom killer is triggered.
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