[PATCH v6 07/21] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1
From: Will Deacon <will@kernel.org>
Date: 2021-05-18 09:48:39
Also in:
linux-arm-kernel, lkml
Subsystem:
control group (cgroup), control group - cpuset, the rest · Maintainers:
Tejun Heo, Johannes Weiner, Michal Koutný, Waiman Long, Linus Torvalds
If the scheduler cannot find an allowed CPU for a task, cpuset_cpus_allowed_fallback() will widen the affinity to cpu_possible_mask if cgroup v1 is in use. In preparation for allowing architectures to provide their own fallback mask, just return early if we're either using cgroup v1 or we're using cgroup v2 with a mask that contains invalid CPUs. This will allow select_fallback_rq() to figure out the mask by itself. Cc: Li Zefan <redacted> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Quentin Perret <redacted> Signed-off-by: Will Deacon <will@kernel.org> --- include/linux/cpuset.h | 1 + kernel/cgroup/cpuset.c | 12 ++++++++++-- 2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 04c20de66afc..ed6ec677dd6b 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h@@ -15,6 +15,7 @@ #include <linux/cpumask.h> #include <linux/nodemask.h> #include <linux/mm.h> +#include <linux/mmu_context.h> #include <linux/jump_label.h> #ifdef CONFIG_CPUSETS
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index a945504c0ae7..8c799260a4a2 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c@@ -3322,9 +3322,17 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) void cpuset_cpus_allowed_fallback(struct task_struct *tsk) { + const struct cpumask *cs_mask; + const struct cpumask *possible_mask = task_cpu_possible_mask(tsk); + rcu_read_lock(); - do_set_cpus_allowed(tsk, is_in_v2_mode() ? - task_cs(tsk)->cpus_allowed : cpu_possible_mask); + cs_mask = task_cs(tsk)->cpus_allowed; + + if (!is_in_v2_mode() || !cpumask_subset(cs_mask, possible_mask)) + goto unlock; /* select_fallback_rq will try harder */ + + do_set_cpus_allowed(tsk, cs_mask); +unlock: rcu_read_unlock(); /*
--
2.31.1.751.gd2f1c929bd-goog