testing/lxd-4.19 broken

Hi there, It looks like lxd-4.19 is broken on edge/testing. Reverting it manually to lxd-4.18 with a local dev pkg build seems to work again.

Containers refuses to launch with lxd-4.19 with the following:

~# lxc info --show-log alpine-test
Name: alpine-test
Status: STOPPED
Type: container
Architecture: x86_64
Created: 2021/09/22 22:38 PDT  
Last Used: 2021/10/25 23:04 PDT

Log:

lxc alpine-test 20211026060445.130 ERROR    start - start.c:core_scheduling:1570 - Invalid argument - The kernel does not support core scheduling
lxc alpine-test 20211026060445.130 ERROR    lxccontainer - lxccontainer.c:wait_on_daemonized_start:867 - Received container state "ABORTING" instead of "RUNNING"
lxc alpine-test 20211026060445.131 ERROR    start - start.c:__lxc_start:2068 - Failed to spawn container "alpine-test"
lxc alpine-test 20211026060445.131 WARN     start - start.c:lxc_abort:1038 - No such process - Failed to send SIGKILL via pidfd 45 for process 26217
lxc 20211026060450.151 ERROR    af_unix - af_unix.c:lxc_abstract_unix_recv_fds_iov:218 - Connection reset by peer - Failed to receive response
lxc 20211026060450.151 ERROR    commands - commands.c:lxc_cmd_rsp_recv_fds:127 - Failed to receive file descriptors

Of course, there are likely some changes upstream that depends on this kernel feature. Speaking of which, my system configuration:

# uname -a
Linux alpine-host 5.10.75-0-virt #1-Alpine SMP Thu, 21 Oct 2021 09:03:21 +0000 x86_64 Linux
# cat /etc/alpine-release
3.15.0_alpha20210804

Reproducible on both -virt and -lts kernel.

NOTE: Downgrading will also cause the lxd database to be incompatible and refuses to startup :( . I haven't looked into this area yet.