When we clear cpuset.cpus, cpuset.effective_cpus won't be cleared:
# mount -t cgroup -o cpuset xxx /mnt
# mkdir /mnt/tmp
# echo 0 > /mnt/tmp/cpuset.cpus
# echo > /mnt/tmp/cpuset.cpus
# cat cpuset.cpus
# cat cpuset.effective_cpus
0-15
And a kernel warning in update_cpumasks_hier() is triggered:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 4028 at kernel/cpuset.c:894
update_cpumasks_hier+0x471/0x650()
Cc: <sta...@vger.kernel.org> # 3.17+
Signed-off-by: Zefan Li <lize...@huawei.com>
---
kernel/cpuset.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 7e9d711..29463c2 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -873,7 +873,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct
cpumask *new_cpus)
* If it becomes empty, inherit the effective mask of the
* parent, which is guaranteed to have some CPUs.
*/
- if (cpumask_empty(new_cpus))
+ if (cgroup_on_dfl(cp->css.cgroup) && cpumask_empty(new_cpus))
cpumask_copy(new_cpus, parent->effective_cpus);
/* Skip the whole subtree if the cpumask remains the same. */
@@ -1129,7 +1129,7 @@ static void update_nodemasks_hier(struct cpuset *cs,
nodemask_t *new_mems)
* If it becomes empty, inherit the effective mask of the
* parent, which is guaranteed to have some MEMs.
*/
- if (nodes_empty(*new_mems))
+ if (cgroup_on_dfl(cp->css.cgroup) && nodes_empty(*new_mems))
*new_mems = parent->effective_mems;
/* Skip the whole subtree if the nodemask remains the same. */
--
1.8.0.2
--
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