From 05f7468584caa0092b212eba6c9bff166a013ca2 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Sun, 27 Aug 2023 10:04:14 +0200 Subject: [PATCH] 5.15-stable patches added patches: torture-fix-hang-during-kthread-shutdown-phase.patch --- queue-5.15/series | 1 + ...x-hang-during-kthread-shutdown-phase.patch | 54 +++++++++++++++++++ 2 files changed, 55 insertions(+) create mode 100644 queue-5.15/torture-fix-hang-during-kthread-shutdown-phase.patch diff --git a/queue-5.15/series b/queue-5.15/series index b43e965c794..460946fbd4b 100644 --- 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 index 00000000000..8be693996fa --- /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)" +Date: Sun, 1 Jan 2023 06:15:55 +0000 +Subject: torture: Fix hang during kthread shutdown phase + +From: Joel Fernandes (Google) + +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 +Cc: Frederic Weisbecker +Cc: Zhouyi Zhou +Cc: # 6.0.x +Signed-off-by: Joel Fernandes (Google) +Tested-by: Zhouyi Zhou +Reviewed-by: Davidlohr Bueso +Signed-off-by: Paul E. McKenney +Signed-off-by: Greg Kroah-Hartman +--- + 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); -- 2.47.3