cgroup: use nodes_and() output where appropriate

Now that nodes_and() returns true if the result nodemask is not empty,
drop useless nodes_intersects() in guarantee_online_mems() and
nodes_empty() in update_nodemasks_hier(), which both are O(N).

Link: https://lkml.kernel.org/r/20260114172217.861204-4-ynorov@nvidia.com
Signed-off-by: Yury Norov <ynorov@nvidia.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Waiman Long <longman@redhat.com>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index c06e2e96f79dcdf5a50e5a8fab5a61b313498afa..99cf37e7d491b1106dd60ba4a8e41d3a5448b981 100644 (file)
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -453,9 +453,8 @@ static void guarantee_active_cpus(struct task_struct *tsk,
  */
 static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
 {
-       while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
+       while (!nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]))
                cs = parent_cs(cs);
-       nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
 }
 
 /**
@@ -2859,13 +2858,13 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
        cpuset_for_each_descendant_pre(cp, pos_css, cs) {
                struct cpuset *parent = parent_cs(cp);
 
-               nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
+               bool has_mems = nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
 
                /*
                 * If it becomes empty, inherit the effective mask of the
                 * parent, which is guaranteed to have some MEMs.
                 */
-               if (is_in_v2_mode() && nodes_empty(*new_mems))
+               if (is_in_v2_mode() && !has_mems)
                        *new_mems = parent->effective_mems;
 
                /* Skip the whole subtree if the nodemask remains the same. */