From: Will Deacon will@kernel.org
[ Upstream commit 7a2127e66a00e073db8d90f9aac308f4a8a64226 ]
set_cpus_allowed_ptr() will fail with -EINVAL if the requested affinity mask is not a subset of the task_cpu_possible_mask() for the task being updated. Consequently, on a heterogeneous system with cpusets spanning the different CPU types, updates to the cgroup hierarchy can silently fail to update task affinities when the effective affinity mask for the cpuset is expanded.
For example, consider an arm64 system with 4 CPUs, where CPUs 2-3 are the only cores capable of executing 32-bit tasks. Attaching a 32-bit task to a cpuset containing CPUs 0-2 will correctly affine the task to CPU 2. Extending the cpuset to CPUs 0-3, however, will fail to extend the affinity mask of the 32-bit task because update_tasks_cpumask() will pass the full 0-3 mask to set_cpus_allowed_ptr().
Extend update_tasks_cpumask() to take a temporary 'cpumask' paramater and use it to mask the 'effective_cpus' mask with the possible mask for each task being updated.
Fixes: 431c69fac05b ("cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus()") Signed-off-by: Will Deacon will@kernel.org Acked-by: Waiman Long longman@redhat.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/cgroup/cpuset.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index a753adcbc7c70..fac4260366208 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1201,12 +1201,13 @@ void rebuild_sched_domains(void) /** * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset. * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed + * @new_cpus: the temp variable for the new effective_cpus mask * * Iterate through each task of @cs updating its cpus_allowed to the * effective cpuset's. As this function is called with cpuset_rwsem held, * cpuset membership stays stable. */ -static void update_tasks_cpumask(struct cpuset *cs) +static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus) { struct css_task_iter it; struct task_struct *task; @@ -1220,7 +1221,10 @@ static void update_tasks_cpumask(struct cpuset *cs) if (top_cs && (task->flags & PF_KTHREAD) && kthread_is_per_cpu(task)) continue; - set_cpus_allowed_ptr(task, cs->effective_cpus); + + cpumask_and(new_cpus, cs->effective_cpus, + task_cpu_possible_mask(task)); + set_cpus_allowed_ptr(task, new_cpus); } css_task_iter_end(&it); } @@ -1505,7 +1509,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, spin_unlock_irq(&callback_lock);
if (adding || deleting) - update_tasks_cpumask(parent); + update_tasks_cpumask(parent, tmp->new_cpus);
/* * Set or clear CS_SCHED_LOAD_BALANCE when partcmd_update, if necessary. @@ -1657,7 +1661,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, WARN_ON(!is_in_v2_mode() && !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
- update_tasks_cpumask(cp); + update_tasks_cpumask(cp, tmp->new_cpus);
/* * On legacy hierarchy, if the effective cpumask of any non- @@ -2305,7 +2309,7 @@ static int update_prstate(struct cpuset *cs, int new_prs) } }
- update_tasks_cpumask(parent); + update_tasks_cpumask(parent, tmpmask.new_cpus);
if (parent->child_ecpus_count) update_sibling_cpumasks(parent, cs, &tmpmask); @@ -3318,7 +3322,7 @@ hotplug_update_tasks_legacy(struct cpuset *cs, * as the tasks will be migrated to an ancestor. */ if (cpus_updated && !cpumask_empty(cs->cpus_allowed)) - update_tasks_cpumask(cs); + update_tasks_cpumask(cs, new_cpus); if (mems_updated && !nodes_empty(cs->mems_allowed)) update_tasks_nodemask(cs);
@@ -3355,7 +3359,7 @@ hotplug_update_tasks(struct cpuset *cs, spin_unlock_irq(&callback_lock);
if (cpus_updated) - update_tasks_cpumask(cs); + update_tasks_cpumask(cs, new_cpus); if (mems_updated) update_tasks_nodemask(cs); }