It was found that commit 7a2127e66a00 ("cpuset: Call
set_cpus_allowed_ptr() with appropriate mask for task") introduced a bug
that corrupted "cpuset.cpus" of a partition root when it was updated.
It is because the tmp->new_cpus field of the passed tmp parameter
of update_parent_subparts_cpumask() should not be used at all as
it contains important cpumask data that should not be overwritten.
Fix it by using tmp->addmask instead.
Also update update_cpumask() to make sure that trialcs->cpu_allowed
will not be corrupted until it is no longer needed.
Fixes: 7a2127e66a00 ("cpuset: Call set_cpus_allowed_ptr() with appropriate mask for task")
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
---
kernel/cgroup/cpuset.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 636f1c682ac0..f310915d1257 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1513,7 +1513,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
spin_unlock_irq(&callback_lock);
if (adding || deleting)
- update_tasks_cpumask(parent, tmp->new_cpus);
+ update_tasks_cpumask(parent, tmp->addmask);
/*
* Set or clear CS_SCHED_LOAD_BALANCE when partcmd_update, if necessary.
@@ -1770,10 +1770,13 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
/*
* Use the cpumasks in trialcs for tmpmasks when they are pointers
* to allocated cpumasks.
+ *
+ * Note that update_parent_subparts_cpumask() uses only addmask &
+ * delmask, but not new_cpus.
*/
tmp.addmask = trialcs->subparts_cpus;
tmp.delmask = trialcs->effective_cpus;
- tmp.new_cpus = trialcs->cpus_allowed;
+ tmp.new_cpus = NULL;
#endif
retval = validate_change(cs, trialcs);
@@ -1838,6 +1841,11 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
}
spin_unlock_irq(&callback_lock);
+#ifdef CONFIG_CPUMASK_OFFSTACK
+ /* Now trialcs->cpus_allowed is available */
+ tmp.new_cpus = trialcs->cpus_allowed;
+#endif
+
/* effective_cpus will be updated here */
update_cpumasks_hier(cs, &tmp, false);
--
2.31.1
