From 44e9d308a51fbf6d2e5a913f7452a5d5f1902249 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Thu, 12 Sep 2019 10:56:44 -0700 Subject: kselftests: cgroup: add freezer mkdir test Add a new cgroup freezer selftest, which checks that if a cgroup is frozen, their new child cgroups will properly inherit the frozen state. It creates a parent cgroup, freezes it, creates a child cgroup and populates it with a dummy process. Then it checks that both parent and child cgroup are frozen. Signed-off-by: Roman Gushchin Cc: Tejun Heo Cc: Shuah Khan Signed-off-by: Tejun Heo --- tools/testing/selftests/cgroup/test_freezer.c | 54 +++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/tools/testing/selftests/cgroup/test_freezer.c b/tools/testing/selftests/cgroup/test_freezer.c index 8219a30853d2..0fc1b6d4b0f9 100644 --- a/tools/testing/selftests/cgroup/test_freezer.c +++ b/tools/testing/selftests/cgroup/test_freezer.c @@ -447,6 +447,59 @@ cleanup: return ret; } +/* + * The test creates a cgroups and freezes it. Then it creates a child cgroup + * and populates it with a task. After that it checks that the child cgroup + * is frozen and the parent cgroup remains frozen too. + */ +static int test_cgfreezer_mkdir(const char *root) +{ + int ret = KSFT_FAIL; + char *parent, *child = NULL; + int pid; + + parent = cg_name(root, "cg_test_mkdir_A"); + if (!parent) + goto cleanup; + + child = cg_name(parent, "cg_test_mkdir_B"); + if (!child) + goto cleanup; + + if (cg_create(parent)) + goto cleanup; + + if (cg_freeze_wait(parent, true)) + goto cleanup; + + if (cg_create(child)) + goto cleanup; + + pid = cg_run_nowait(child, child_fn, NULL); + if (pid < 0) + goto cleanup; + + if (cg_wait_for_proc_count(child, 1)) + goto cleanup; + + if (cg_check_frozen(child, true)) + goto cleanup; + + if (cg_check_frozen(parent, true)) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + if (child) + cg_destroy(child); + free(child); + if (parent) + cg_destroy(parent); + free(parent); + return ret; +} + /* * The test creates two nested cgroups, freezes the parent * and removes the child. Then it checks that the parent cgroup @@ -815,6 +868,7 @@ struct cgfreezer_test { T(test_cgfreezer_simple), T(test_cgfreezer_tree), T(test_cgfreezer_forkbomb), + T(test_cgfreezer_mkdir), T(test_cgfreezer_rmdir), T(test_cgfreezer_migrate), T(test_cgfreezer_ptrace), -- cgit From 97a61369830ab085df5aed0ff9256f35b07d425a Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Thu, 12 Sep 2019 10:56:45 -0700 Subject: cgroup: freezer: fix frozen state inheritance If a new child cgroup is created in the frozen cgroup hierarchy (one or more of ancestor cgroups is frozen), the CGRP_FREEZE cgroup flag should be set. Otherwise if a process will be attached to the child cgroup, it won't become frozen. The problem can be reproduced with the test_cgfreezer_mkdir test. This is the output before this patch: ~/test_freezer ok 1 test_cgfreezer_simple ok 2 test_cgfreezer_tree ok 3 test_cgfreezer_forkbomb Cgroup /sys/fs/cgroup/cg_test_mkdir_A/cg_test_mkdir_B isn't frozen not ok 4 test_cgfreezer_mkdir ok 5 test_cgfreezer_rmdir ok 6 test_cgfreezer_migrate ok 7 test_cgfreezer_ptrace ok 8 test_cgfreezer_stopped ok 9 test_cgfreezer_ptraced ok 10 test_cgfreezer_vfork And with this patch: ~/test_freezer ok 1 test_cgfreezer_simple ok 2 test_cgfreezer_tree ok 3 test_cgfreezer_forkbomb ok 4 test_cgfreezer_mkdir ok 5 test_cgfreezer_rmdir ok 6 test_cgfreezer_migrate ok 7 test_cgfreezer_ptrace ok 8 test_cgfreezer_stopped ok 9 test_cgfreezer_ptraced ok 10 test_cgfreezer_vfork Reported-by: Mark Crossen Signed-off-by: Roman Gushchin Fixes: 76f969e8948d ("cgroup: cgroup v2 freezer") Cc: Tejun Heo Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Tejun Heo --- kernel/cgroup/cgroup.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 753afbca549f..8be1da1ebd9a 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5255,8 +5255,16 @@ static struct cgroup *cgroup_create(struct cgroup *parent) * if the parent has to be frozen, the child has too. */ cgrp->freezer.e_freeze = parent->freezer.e_freeze; - if (cgrp->freezer.e_freeze) + if (cgrp->freezer.e_freeze) { + /* + * Set the CGRP_FREEZE flag, so when a process will be + * attached to the child cgroup, it will become frozen. + * At this point the new cgroup is unpopulated, so we can + * consider it frozen immediately. + */ + set_bit(CGRP_FREEZE, &cgrp->flags); set_bit(CGRP_FROZEN, &cgrp->flags); + } spin_lock_irq(&css_set_lock); for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) { -- cgit