Comment 0 for bug 1800849

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 relaese the mm_sem
                  when needed.

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

kernel 4.19
Upstream-ID: 306d6c49ac9ded11114cb53b0925da52f2c2ada1