selftests: pid_namespace: test fork with dead ancestor

Add a regression test for fork() into a PID namespace whose parent
namespace has lost its init process. Since the kernel cannot assign the
new process a PID in that dead ancestor, fork() must fail with ENOMEM.

Create the nested PID namespaces, keep the child namespace handle open
after its init process exits, then enter it and verify fork() fails.

Register the test with the PID namespace selftests and ignore its
generated binary. Skip when namespace operations are denied or procfs
cannot provide the pid_for_children handle.

Signed-off-by: Sahaj Chaudhari <sahaj123.sc@gmail.com>
Link: https://patch.msgid.link/20261007114914.1668934-1-sahaj123.sc@gmail.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

0 files changed, 0 insertions, 0 deletions