| Message ID | 20220425155505.1292896-1-longman@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] cgroup/cpuset: Remove cpus_allowed/mems_allowed setup in cpuset_init_smp() | expand |
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 9390bfd9f1cd..6bd8f5ef40fe 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -3390,8 +3390,9 @@ static struct notifier_block cpuset_track_online_nodes_nb = { */ void __init cpuset_init_smp(void) { - cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask); - top_cpuset.mems_allowed = node_states[N_MEMORY]; + /* + * cpus_allowd/mems_allowed will be properly set up in cpuset_bind(). + */ top_cpuset.old_mems_allowed = top_cpuset.mems_allowed; cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
There are 3 places where the cpu and node masks of the top cpuset can be initialized in the order they are executed: 1) start_kernel -> cpuset_init() 2) start_kernel -> cgroup_init() -> cpuset_bind() 3) kernel_init_freeable() -> do_basic_setup() -> cpuset_init_smp() The first cpuset_init() function just sets all the bits in the masks. The last one executed is cpuset_init_smp() which sets up cpu and node masks suitable for v1, but not v2. cpuset_bind() does the right setup for both v1 and v2. For systems with cgroup v2 setup, cpuset_bind() is called once. For systems with cgroup v1 setup, cpuset_bind() is called twice. It is first called before cpuset_init_smp() in cgroup v2 mode. Then it is called again when cgroup v1 filesystem is mounted in v1 mode after cpuset_init_smp(). [ 2.609781] cpuset_bind() called - v2 = 1 [ 3.079473] cpuset_init_smp() called [ 7.103710] cpuset_bind() called - v2 = 0 As a result, cpu and memory node hot add may fail to update the cpu and node masks of the top cpuset to include the newly added cpu or node in a cgroup v2 environment. smp_init() is called after the first two init functions. So we don't have a complete list of active cpus and memory nodes until later in cpuset_init_smp() which is the right time to set up effective_cpus and effective_mems. To fix this problem, the potentially incorrect cpus_allowed & mems_allowed setup in cpuset_init_smp() are removed. For cgroup v2 systems, the initial cpuset_bind() call will set them up correctly. For cgroup v1 systems, the second call to cpuset_bind() will do the right setup. cc: stable@vger.kernel.org Signed-off-by: Waiman Long <longman@redhat.com> --- kernel/cgroup/cpuset.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)