5.4-stable patches

added patches:
	cgroup-cpuset-fix-suspicious-rcu-usage-lockdep-warning.patch

diff --git a/queue-5.4/cgroup-cpuset-fix-suspicious-rcu-usage-lockdep-warning.patch b/queue-5.4/cgroup-cpuset-fix-suspicious-rcu-usage-lockdep-warning.patch
new file mode 100644 (file)
index 0000000..52408e2
--- /dev/null
+++ b/queue-5.4/cgroup-cpuset-fix-suspicious-rcu-usage-lockdep-warning.patch
@@ -0,0 +1,60 @@
+From 2bdfd2825c9662463371e6691b1a794e97fa36b4 Mon Sep 17 00:00:00 2001
+From: Waiman Long <longman@redhat.com>
+Date: Wed, 2 Feb 2022 22:31:03 -0500
+Subject: cgroup/cpuset: Fix "suspicious RCU usage" lockdep warning
+
+From: Waiman Long <longman@redhat.com>
+
+commit 2bdfd2825c9662463371e6691b1a794e97fa36b4 upstream.
+
+It was found that a "suspicious RCU usage" lockdep warning was issued
+with the rcu_read_lock() call in update_sibling_cpumasks().  It is
+because the update_cpumasks_hier() function may sleep. So we have
+to release the RCU lock, call update_cpumasks_hier() and reacquire
+it afterward.
+
+Also add a percpu_rwsem_assert_held() in update_sibling_cpumasks()
+instead of stating that in the comment.
+
+Fixes: 4716909cc5c5 ("cpuset: Track cpusets that use parent's effective_cpus")
+Signed-off-by: Waiman Long <longman@redhat.com>
+Tested-by: Phil Auld <pauld@redhat.com>
+Reviewed-by: Phil Auld <pauld@redhat.com>
+Signed-off-by: Tejun Heo <tj@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/cgroup/cpuset.c |   10 ++++++++++
+ 1 file changed, 10 insertions(+)
+
+--- a/kernel/cgroup/cpuset.c
++++ b/kernel/cgroup/cpuset.c
+@@ -1473,10 +1473,15 @@ static void update_sibling_cpumasks(stru
+       struct cpuset *sibling;
+       struct cgroup_subsys_state *pos_css;
+ 
++      percpu_rwsem_assert_held(&cpuset_rwsem);
++
+       /*
+        * Check all its siblings and call update_cpumasks_hier()
+        * if their use_parent_ecpus flag is set in order for them
+        * to use the right effective_cpus value.
++       *
++       * The update_cpumasks_hier() function may sleep. So we have to
++       * release the RCU read lock before calling it.
+        */
+       rcu_read_lock();
+       cpuset_for_each_child(sibling, pos_css, parent) {
+@@ -1484,8 +1489,13 @@ static void update_sibling_cpumasks(stru
+                       continue;
+               if (!sibling->use_parent_ecpus)
+                       continue;
++              if (!css_tryget_online(&sibling->css))
++                      continue;
+ 
++              rcu_read_unlock();
+               update_cpumasks_hier(sibling, tmp);
++              rcu_read_lock();
++              css_put(&sibling->css);
+       }
+       rcu_read_unlock();
+ }

diff --git a/queue-5.4/series b/queue-5.4/series
index 8781658535680cb9e68fbfc97e03af212ba0c0e7..101770e6b2a8a976c18cca540aa6253c45ed5944 100644 (file)
--- a/queue-5.4/series
+++ b/queue-5.4/series
@@ -41,3 +41,4 @@ rtc-cmos-evaluate-century-appropriate.patch
 edac-altera-fix-deferred-probing.patch
 edac-xgene-fix-deferred-probing.patch
 ext4-fix-error-handling-in-ext4_restore_inline_data.patch
+cgroup-cpuset-fix-suspicious-rcu-usage-lockdep-warning.patch