libctr: Reset the inherited cpu affinity

Old kernels do that automatically, but new kernels remember
the affinity that was set before the cgroup move due to

https://lore.kernel.org/lkml/[email protected]

This is undesirable for containers, because they inherit
the systemd affinity when the should really move to the container
space cpus.

Signed-off-by: Martin Sivak <[email protected]>
Signed-off-by: Peter Hunt <[email protected]>

Author: haircommander

libcontainer/process_linux.go

@@ -11,6 +11,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"strconv"
+	"syscall"
 	"time"
 
 	"github.com/opencontainers/runc/libcontainer/cgroups"
@@ -144,6 +145,14 @@ func (p *setnsProcess) start() (retErr error) {
 			}
 		}
 	}
+	// Reset the inherited cpu affinity. Old kernels do that automatically, but
+	// new kernels remember the affinity that was set before the cgroup move.
+	// This is undesirable, because it inherits the systemd affinity when the container
+	// should really move to the container space cpus.
+	if err = unix.SchedSetaffinity(p.pid(), &unix.CPUSet{}); err != nil && !errors.Is(err, syscall.EINVAL) && !errors.Is(err, syscall.ENODEV) {
+		return fmt.Errorf("error resetting pid %d affinity: %w", p.pid(), err)
+	}
+
 	if p.intelRdtPath != "" {
 		// if Intel RDT "resource control" filesystem path exists
 		_, err := os.Stat(p.intelRdtPath)