From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Wed, 23 Feb 2022 18:11:07 +0000 (+0100)
Subject: 5.10-stable patches
X-Git-Tag: v4.9.304~77
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6686e0c577c8a8c7fc5151ab14373cce5e628ae3;p=thirdparty%2Fkernel%2Fstable-queue.git

5.10-stable patches

added patches:
	cgroup-cpuset-fix-a-race-between-cpuset_attach-and-cpu-hotplug.patch
---

diff --git a/queue-5.10/cgroup-cpuset-fix-a-race-between-cpuset_attach-and-cpu-hotplug.patch b/queue-5.10/cgroup-cpuset-fix-a-race-between-cpuset_attach-and-cpu-hotplug.patch
new file mode 100644
index 00000000000..0123f2a932e
--- /dev/null
+++ b/queue-5.10/cgroup-cpuset-fix-a-race-between-cpuset_attach-and-cpu-hotplug.patch
@@ -0,0 +1,62 @@
+From 05c7b7a92cc87ff8d7fde189d0fade250697573c Mon Sep 17 00:00:00 2001
+From: Zhang Qiao <zhangqiao22@huawei.com>
+Date: Fri, 21 Jan 2022 18:12:10 +0800
+Subject: cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Zhang Qiao <zhangqiao22@huawei.com>
+
+commit 05c7b7a92cc87ff8d7fde189d0fade250697573c upstream.
+
+As previously discussed(https://lkml.org/lkml/2022/1/20/51),
+cpuset_attach() is affected with similar cpu hotplug race,
+as follow scenario:
+
+     cpuset_attach()				cpu hotplug
+    ---------------------------            ----------------------
+    down_write(cpuset_rwsem)
+    guarantee_online_cpus() // (load cpus_attach)
+					sched_cpu_deactivate
+					  set_cpu_active()
+					  // will change cpu_active_mask
+    set_cpus_allowed_ptr(cpus_attach)
+      __set_cpus_allowed_ptr_locked()
+       // (if the intersection of cpus_attach and
+         cpu_active_mask is empty, will return -EINVAL)
+    up_write(cpuset_rwsem)
+
+To avoid races such as described above, protect cpuset_attach() call
+with cpu_hotplug_lock.
+
+Fixes: be367d099270 ("cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time")
+Cc: stable@vger.kernel.org # v2.6.32+
+Reported-by: Zhao Gongyi <zhaogongyi@huawei.com>
+Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
+Acked-by: Waiman Long <longman@redhat.com>
+Reviewed-by: Michal Koutný <mkoutny@suse.com>
+Signed-off-by: Tejun Heo <tj@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/cgroup/cpuset.c |    2 ++
+ 1 file changed, 2 insertions(+)
+
+--- a/kernel/cgroup/cpuset.c
++++ b/kernel/cgroup/cpuset.c
+@@ -2212,6 +2212,7 @@ static void cpuset_attach(struct cgroup_
+ 	cgroup_taskset_first(tset, &css);
+ 	cs = css_cs(css);
+ 
++	cpus_read_lock();
+ 	percpu_down_write(&cpuset_rwsem);
+ 
+ 	/* prepare for attach */
+@@ -2267,6 +2268,7 @@ static void cpuset_attach(struct cgroup_
+ 		wake_up(&cpuset_attach_wq);
+ 
+ 	percpu_up_write(&cpuset_rwsem);
++	cpus_read_unlock();
+ }
+ 
+ /* The various types of files and directories in a cpuset file system */
diff --git a/queue-5.10/series b/queue-5.10/series
new file mode 100644
index 00000000000..5ac931fd893
--- /dev/null
+++ b/queue-5.10/series
@@ -0,0 +1 @@
+cgroup-cpuset-fix-a-race-between-cpuset_attach-and-cpu-hotplug.patch