kselftests: cgroup: add freezer controller self-tests

2019-04-19T18:26:49Z

This patch implements 9 tests for the freezer controller for cgroup v2: 1) a simple test, which aims to freeze and unfreeze a cgroup with 100 processes 2) a more complicated tree test, which creates a hierarchy of cgroups, puts some processes in some cgroups, and tries to freeze and unfreeze different parts of the subtree 3) a forkbomb test: the test aims to freeze a forkbomb running in a cgroup, kill all tasks in the cgroup and remove the cgroup without the unfreezing. 4) rmdir test: the test creates two nested cgroups, freezes the parent one, checks that the child can be successfully removed, and a new child can be created 5) migration tests: the test checks migration of a task between frozen cgroups: from a frozen to a running, from a running to a frozen, and from a frozen to a frozen. 6) ptrace test: the test checks that it's possible to attach to a process in a frozen cgroup, get some information and detach, and the cgroup will remain frozen. 7) stopped test: the test checks that it's possible to freeze a cgroup with a stopped task 8) ptraced test: the test checks that it's possible to freeze a cgroup with a ptraced task 9) vfork test: the test checks that it's possible to freeze a cgroup with a parent process waiting for the child process in vfork() Expected output: $ ./test_freezer ok 1 test_cgfreezer_simple ok 2 test_cgfreezer_tree ok 3 test_cgfreezer_forkbomb ok 4 test_cgrreezer_rmdir ok 5 test_cgfreezer_migrate ok 6 test_cgfreezer_ptrace ok 7 test_cgfreezer_stopped ok 8 test_cgfreezer_ptraced ok 9 test_cgfreezer_vfork Signed-off-by: Roman Gushchin Signed-off-by: Tejun Heo Cc: Shuah Khan Cc: kernel-team@fb.com Cc: linux-kselftest@vger.kernel.org

kernel/tools/testing/selftests/cgroup/test_freezer.c, branch linux-5.2.y

kselftests: cgroup: add freezer controller self-tests