The root cause of this fail is a wrong mount ID which is reported for file mappings:
Steps to reproduce: root@ubuntu-s-4vcpu-8gb-nyc1-01:~# uname -a Linux ubuntu-s-4vcpu-8gb-nyc1-01 5.3.0-26-generic #28-Ubuntu SMP Wed Dec 18 05:37:46 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux root@ubuntu-s-4vcpu-8gb-nyc1-01:~# docker run -it --rm --privileged busybox / # ls -l /proc/1/map_files/ total 0 lr-------- 1 root root 64 Jan 7 18:59 400000-401000 -> /bin/sh lr-------- 1 root root 64 Jan 7 19:00 401000-4dd000 -> /bin/sh lr-------- 1 root root 64 Jan 7 19:00 4dd000-514000 -> /bin/sh lr-------- 1 root root 64 Jan 7 19:00 514000-516000 -> /bin/sh / # exec 50</proc/1/map_files/400000-401000 / # cat /proc/self/fdinfo/50 pos: 0 flags: 0100000 mnt_id: 551 / # cat /proc/self/mountinfo | grep 551 We can see that the mount 551 isn't listed in container mounts. If we will try to open /bin/sh directly, we will see the mount ID of the container root mount. / # exec 50</bin/sh / # cat /proc/self/fdinfo/50 pos: 0 flags: 0100000 mnt_id: 607 / # cat /proc/self/mountinfo | grep '^607' 607 567 0:51 / / rw,relatime master:308 - overlay overlay rw,lowerdir=/var/lib/docker/overlay2/l/DCAEKRDYRDTVUIECWWPMTFAKAO:/var/lib/docker/overlay2/l/BEYAU2IKCGHGS5UYC7C6Q6HIHG,upperdir=/var/lib/docker/overlay2/1c92eec684804fbc8642a9a4698a0099c9ff5c39915289e1fcd1b39493558c65/diff,workdir=/var/lib/docker/overlay2/1c92eec684804fbc8642a9a4698a0099c9ff5c39915289e1fcd1b39493558c65/work,xino=off -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1857257 Title: linux-image-5.0.0-35-generic breaks checkpointing of container To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1857257/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
