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Commit fe5770ae authored by Roman Gushchin's avatar Roman Gushchin Committed by Marco Ballesio
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UPSTREAM: 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: 76f969e8948d ("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>

Change-Id: I6ba7b8dec5600e78bb7448f03fd97a9b43838fa0
(cherry picked from commit 97a61369830ab085df5aed0ff9256f35b07d425a)
Bug: 154548692
Signed-off-by: default avatarMarco Ballesio <balejs@google.com>
parent f7840a0a

kernel/cgroup/cgroup.c

+9 −1
Original line number Diff line number Diff line
@@ -5129,8 +5129,16 @@ 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)) {