This commit (included in 5.6-rc5) seems to be needed for 5.4 and 5.5 branches: commit 6d390e4b5d48ec03bb87e63cf0a2bff5f4e116da Author: yangerkun <yangerkun@xxxxxxxxxx> Date: Wed Mar 4 15:25:56 2020 +0800 locks: fix a potential use-after-free problem when wakeup a waiter I'm a bit surprised that it hasn't yet been applied, while some fixes from 5.6-rc6 have. Ben. -- Ben Hutchings, Software Developer Codethink Ltd https://www.codethink.co.uk/ Dale House, 35 Dale Street Manchester, M1 2HF, United Kingdom