Older kernels did not support this sysctl, but did not restrict userfaultfd in any way so everything worked as if vm.unprivileged_userfaultfd was set to 1. Thus we can safely ignore errors when setting the value. Signed-off-by: Jiri Denemark <jdenemar(a)redhat.com&gt; --- src/qemu/postcopy-migration.sysctl | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/qemu/postcopy-migration.sysctl b/src/qemu/postcopy-migration.sysctl index aa8f015ae0..db3f11e49f 100644 --- a/src/qemu/postcopy-migration.sysctl +++ b/src/qemu/postcopy-migration.sysctl @@ -3,4 +3,4 @@ # privileged processes. # It can be safely overridden by a file in /etc/sysctl.d/ in case post-copy # migration is not used on the host. -vm.unprivileged_userfaultfd = 1 +-vm.unprivileged_userfaultfd = 1 -- 2.35.1