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author | Joel Fernandes (Google) <joel@joelfernandes.org> | 2023-01-01 06:15:55 +0000 |
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committer | Paul E. McKenney <paulmck@kernel.org> | 2023-01-05 12:10:35 -0800 |
commit | d52d3a2bf408ff86f3a79560b5cce80efb340239 (patch) | |
tree | 43351d3edc66beb03f7ccb0f3dca91c2f0e86bb3 /kernel | |
parent | 273661595c21f390d2522af06c7b552f907fe12a (diff) | |
download | linux-stable-d52d3a2bf408ff86f3a79560b5cce80efb340239.tar.gz linux-stable-d52d3a2bf408ff86f3a79560b5cce80efb340239.tar.bz2 linux-stable-d52d3a2bf408ff86f3a79560b5cce80efb340239.zip |
torture: Fix hang during kthread shutdown phase
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>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/torture.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/torture.c b/kernel/torture.c index 29afc62f2bfe..1a0519b836ac 100644 --- a/kernel/torture.c +++ b/kernel/torture.c @@ -915,7 +915,7 @@ void torture_kthread_stopping(char *title) 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); |