Commit 97a61369 authored by Roman Gushchin's avatar Roman Gushchin Committed by Tejun Heo
Browse files

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: default avatarMark Crossen <mcrossen@fb.com>
Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Fixes: 76f969e8

 ("cgroup: cgroup v2 freezer")
Cc: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 44e9d308
......@@ -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)) {
......
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