linux-stable.git/kernel/torture.c, branch v6.6.2

torture: Stop right-shifting torture_random() return values

2023-08-14T22:01:08+00:00

Now that torture_random() uses swahw32(), its callers no longer see
not-so-random low-order bits, as these are now swapped up into the upper
16 bits of the torture_random() function's return value.  This commit
therefore removes the right-shifting of torture_random() return values.

Signed-off-by: Paul E. McKenney

torture: Move stutter_wait() timeouts to hrtimers

2023-08-14T22:01:08+00:00

In order to gain better race coverage, move the test start/stop
waits in stutter_wait() to torture_hrtimeout_jiffies().

Signed-off-by: Paul E. McKenney

torture: Move torture_shuffle() timeouts to hrtimers

2023-08-14T22:01:08+00:00

In order to gain better race coverage, move the CPU-migration timed
waits in torture_shuffle() to torture_hrtimeout_jiffies().

Signed-off-by: Paul E. McKenney

torture: Move torture_onoff() timeouts to hrtimers

2023-08-14T22:01:08+00:00

In order to gain better race coverage, move the CPU-hotplug-related
timed waits in torture_onoff() to torture_hrtimeout_jiffies().

Signed-off-by: Paul E. McKenney

torture: Make torture_hrtimeout_*() use TASK_IDLE

2023-08-14T22:01:07+00:00

Given that it is expected that more code will use torture_hrtimeout_*(),
including for longer timeouts, make it use TASK_IDLE instead of
TASK_UNINTERRUPTIBLE.

Signed-off-by: Paul E. McKenney

torture: Add lock_torture writer_fifo module parameter

2023-08-14T22:01:07+00:00

This commit adds a module parameter that causes the locktorture writer
to run at real-time priority.

To use it:
insmod /lib/modules/torture.ko random_shuffle=1
insmod /lib/modules/locktorture.ko torture_type=mutex_lock rt_boost=1 rt_boost_factor=50 nested_locks=3 writer_fifo=1
													^^^^^^^^^^^^^

A predecessor to this patch has been helpful to uncover issues with the
proxy-execution series.

[ paulmck: Remove locktorture-specific code from kernel/torture.c. ]

Cc: "Paul E. McKenney" 
Cc: Josh Triplett 
Cc: Joel Fernandes 
Cc: Juri Lelli 
Cc: Valentin Schneider 
Cc: kernel-team@android.com
Signed-off-by: Dietmar Eggemann 
[jstultz: Include header change to build, reword commit message]
Signed-off-by: John Stultz 
Acked-by: Davidlohr Bueso 
Signed-off-by: Paul E. McKenney

torture: Add a kthread-creation callback to _torture_create_kthread()

2023-08-14T22:00:37+00:00

This commit adds a kthread-creation callback to the
_torture_create_kthread() function, which allows callers of a new
torture_create_kthread_cb() macro to specify a function to be invoked
after the kthread is created but before it is awakened for the first time.

Signed-off-by: Paul E. McKenney 
Cc: Dietmar Eggemann 
Cc: Josh Triplett 
Cc: Juri Lelli 
Cc: Valentin Schneider 
Cc: Dietmar Eggemann 
Cc: kernel-team@android.com
Reviewed-by: Joel Fernandes (Google) 
Acked-by: John Stultz

torture: Support randomized shuffling for proxy exec testing

2023-07-14T22:04:09+00:00

Currently shuffling sets the same cpu affinities for all tasks,
which makes us less likely to hit paths involving migrating
blocked tasks onto a cpu where they can't run.

This patch adds an element of randomness to allow affinities of
different writer tasks to diverge.

This has helped uncover issues in testing with Proxy Execution

Cc: "Paul E. McKenney" 
Cc: Josh Triplett 
Cc: Joel Fernandes 
Cc: Juri Lelli 
Cc: Valentin Schneider 
Cc: Dietmar Eggemann 
Cc: kernel-team@android.com
Signed-off-by: Connor O'Brien 
Signed-off-by: John Stultz 
Acked-by: Davidlohr Bueso 
Signed-off-by: Paul E. McKenney

torture: Fix hang during kthread shutdown phase

2023-01-05T20:10:35+00:00

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

torture: Seed torture_random_state on CPU

2023-01-04T01:52:54+00:00

The DEFINE_TORTURE_RANDOM_PERCPU() macro defines per-CPU random-number
generators for torture testing, but the seeds for each CPU's instance
will be identical if they are first used at the same time.  This commit
therefore adds the CPU number to the mix when reseeding.

Signed-off-by: Paul E. McKenney