This patch forces container's init process, to become a session leader,
that is its session ID is made the same as its process ID.
That might seem unnecessary in general, but if we want to checkpoint a
container with CRIU, which is needed for container migration,
we must ensure that the SID of each process inside the container points
to a process that lives in the same PID namespace as the container.
Therefore, we force that the session leader is the init.
Signed-off-by: Katerina Koukiou <k.koukiou@xxxxxxxxx>
---
src/lxc/lxc_container.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c
index 916a37b..b857431 100644
--- a/src/lxc/lxc_container.c
+++ b/src/lxc/lxc_container.c
@@ -2245,6 +2245,14 @@ static int lxcContainerChild(void *data)
argv->npassFDs, argv->passFDs) < 0)
goto cleanup;
+ /* Make init process of the container the leader of the new session.
+ * That is needed when checkpointing container.
+ */
+ if (setsid() < 0) {
+ virReportSystemError(errno, "%s",
+ _("Unable to become session leader"));
+ }
+
ret = 0;
cleanup:
VIR_FREE(ttyPath);
--
2.7.3
--
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