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 v1.2.3