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authorWaiman Long <longman@redhat.com>2022-04-27 10:54:28 -0400
committerTejun Heo <tj@kernel.org>2022-05-05 08:57:00 -1000
commit2685027fca387b602ae565bff17895188b803988 (patch)
tree8780f502d8f8c1d479300561cb7625dfecab404c /kernel
parenta7391ad3572431a354c927cf8896e86e50d7d0bf (diff)
downloadlinux-2685027fca387b602ae565bff17895188b803988.tar.bz2
cgroup/cpuset: Remove cpus_allowed/mems_allowed setup in cpuset_init_smp()
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() call just sets all the bits in the masks. The second cpuset_bind() call sets cpus_allowed and mems_allowed to the default v2 values. The third cpuset_init_smp() call sets them back to v1 values. For systems with cgroup v2 setup, cpuset_bind() is called once. 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. For systems with cgroup v1 setup, cpuset_bind() is called again by rebind_subsystem() when the v1 cpuset filesystem is mounted as shown in the dmesg log below with an instrumented kernel. [ 2.609781] cpuset_bind() called - v2 = 1 [ 3.079473] cpuset_init_smp() called [ 7.103710] cpuset_bind() called - v2 = 0 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 cgroup v2 mask setup problem, the potentially incorrect cpus_allowed & mems_allowed setting in cpuset_init_smp() are removed. For cgroup v2 systems, the initial cpuset_bind() call will set the masks 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> Tested-by: Feng Tang <feng.tang@intel.com> Reviewed-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup/cpuset.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 9390bfd9f1cd..71a418858a5e 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3390,8 +3390,11 @@ 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 set to v2 values in the initial
+ * cpuset_bind() call will be reset to v1 values in another
+ * cpuset_bind() call when v1 cpuset is mounted.
+ */
top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);