selftests/cgroup: test clone3() into a previously killed cgroup

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Once cgroup.kill had been written to a cgroup, a stale kill_seq
snapshot (taken in cgroup_css_set_fork() before the target cgroup was
resolved) caused every child subsequently cloned into that cgroup with
clone3(CLONE_INTO_CGROUP) to be SIGKILLed on the spot.

Add a regression test: create a cgroup, kill it while it is empty,
then clone a child into it and check that the child runs and exits
cleanly. On a kernel without the fix, the test fails:

  not ok 4 test_cgkill_clone_into_killed

The test is skipped on kernels without clone3() or without
CLONE_INTO_CGROUP.

Cc: Shakeel Butt <shakeel.butt@linux.dev>
Assisted-by: LLM
Signed-off-by: Etienne Perot <eperot@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

...

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Etienne Perot 2026-08-28 21:52:52 +00:00 • committed by Tejun Heo

parent 8e35992021

commit 3f4b7d1a49

1 changed files with 55 additions and 0 deletions

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tools/testing/selftests/cgroup/test_kill.c

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