On 1/10/25 18:41, Jiri Denemark wrote:
The postcopy-recover migration state in QEMU means a connection for the migration stream was established. Depending on the schedulers on both hosts a relative timing of the corresponding MIGRATION event on the source host and the destination host may differ. Specifically it's possible that the source sees postcopy-recover while the destination is still in postcopy-paused.
Currently the Perform phase on the source host ends when we get postcopy-recover event and the Finish phase on the destination host is called. If this is fast enough we can still see postcopy-paused state when the Finish phase starts waiting for migration to complete. This is interpreted as a failure and reported back to the caller. Even though the recovery may actually start just a few moments later.
To avoid this race we now don't consider post-copy migration active in postcopy-recover state and keep waiting for postcopy-active event (in the success path). Thus the Finish phase is entered only after the migration switches to postcopy-active. In this state QEMU guarantees the destination already switched at least to postcopy-recover and we won't be confused be seeing an old postcopy-failed state.
https://issues.redhat.com/browse/RHEL-73085
Signed-off-by: Jiri Denemark <jdenemar@redhat.com> --- src/qemu/qemu_migration.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Michal Privoznik <mprivozn@redhat.com> Michal