5.15-stable patches

added patches:
	torture-fix-hang-during-kthread-shutdown-phase.patch

diff --git a/queue-5.15/series b/queue-5.15/series
index b43e965c7944fcf3f81d9133a39833e3b4917bd7..460946fbd4b3387a0ebce4eb8374874d10042374 100644 (file)
--- a/queue-5.15/series
+++ b/queue-5.15/series
@@ -72,3 +72,4 @@ x86-fpu-invalidate-fpu-state-correctly-on-exec.patch
 x86-fpu-set-x86_feature_osxsave-feature-after-enabling-osxsave-in-cr4.patch
 nfs-use-vfs-setgid-helper.patch
 nfsd-use-vfs-setgid-helper.patch
+torture-fix-hang-during-kthread-shutdown-phase.patch

diff --git a/queue-5.15/torture-fix-hang-during-kthread-shutdown-phase.patch b/queue-5.15/torture-fix-hang-during-kthread-shutdown-phase.patch
new file mode 100644 (file)
index 0000000..8be6939
--- /dev/null
+++ b/queue-5.15/torture-fix-hang-during-kthread-shutdown-phase.patch
@@ -0,0 +1,54 @@
+From d52d3a2bf408ff86f3a79560b5cce80efb340239 Mon Sep 17 00:00:00 2001
+From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
+Date: Sun, 1 Jan 2023 06:15:55 +0000
+Subject: torture: Fix hang during kthread shutdown phase
+
+From: Joel Fernandes (Google) <joel@joelfernandes.org>
+
+commit d52d3a2bf408ff86f3a79560b5cce80efb340239 upstream.
+
+During rcutorture shutdown, the rcu_torture_cleanup() function calls
+torture_cleanup_begin(), which sets the fullstop global variable to
+FULLSTOP_RMMOD. This causes the rcutorture threads for readers and
+fakewriters to exit all of their "while" loops and start shutting down.
+
+They then call torture_kthread_stopping(), which in turn waits for
+kthread_stop() to be called.  However, rcu_torture_cleanup() has
+not yet called kthread_stop() on those threads, and before it gets a
+chance to do so, multiple instances of torture_kthread_stopping() invoke
+schedule_timeout_interruptible(1) in a tight loop.  Tracing confirms that
+TIMER_SOFTIRQ can then continuously execute timer callbacks.  If that
+TIMER_SOFTIRQ preempts the task executing rcu_torture_cleanup(), that
+task might never invoke kthread_stop().
+
+This commit improves this situation by increasing the timeout passed to
+schedule_timeout_interruptible() from one jiffy to 1/20th of a second.
+This change prevents TIMER_SOFTIRQ from monopolizing its CPU, thus
+allowing rcu_torture_cleanup() to carry out the needed kthread_stop()
+invocations.  Testing has shown 100 runs of TREE07 passing reliably,
+as oppose to the tens-of-percent failure rates seen beforehand.
+
+Cc: Paul McKenney <paulmck@kernel.org>
+Cc: Frederic Weisbecker <fweisbec@gmail.com>
+Cc: Zhouyi Zhou <zhouzhouyi@gmail.com>
+Cc: <stable@vger.kernel.org> # 6.0.x
+Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
+Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
+Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
+Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/torture.c |    2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/kernel/torture.c
++++ b/kernel/torture.c
+@@ -915,7 +915,7 @@ void torture_kthread_stopping(char *titl
+       VERBOSE_TOROUT_STRING(buf);
+       while (!kthread_should_stop()) {
+               torture_shutdown_absorb(title);
+-              schedule_timeout_uninterruptible(1);
++              schedule_timeout_uninterruptible(HZ / 20);
+       }
+ }
+ EXPORT_SYMBOL_GPL(torture_kthread_stopping);