This is a note to let you know that I've just added the patch titled
cgroup/cpuset: Fix partition root's cpuset.cpus update bug
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cgroup-cpuset-fix-partition-root-s-cpuset.cpus-update-bug.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 292fd843de26c551856e66faf134512c52dd78b4 Mon Sep 17 00:00:00 2001
From: Waiman Long <longman@xxxxxxxxxx>
Date: Fri, 17 Mar 2023 11:15:05 -0400
Subject: cgroup/cpuset: Fix partition root's cpuset.cpus update bug
From: Waiman Long <longman@xxxxxxxxxx>
commit 292fd843de26c551856e66faf134512c52dd78b4 upstream.
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>
Cc: stable@xxxxxxxxxxxxxxx # v6.2+
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/cgroup/cpuset.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1513,7 +1513,7 @@ static int update_parent_subparts_cpumas
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
/*
* 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
}
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);
Patches currently in stable-queue which might be from longman@xxxxxxxxxx are
queue-6.2/cgroup-cpuset-make-cpuset_fork-handle-clone_into_cgroup-properly.patch
queue-6.2/cgroup-cpuset-add-cpuset_can_fork-and-cpuset_cancel_fork-methods.patch
queue-6.2/cgroup-cpuset-wake-up-cpuset_attach_wq-tasks-in-cpuset_cancel_attach.patch
queue-6.2/cgroup-cpuset-fix-partition-root-s-cpuset.cpus-update-bug.patch
