The rt boosting in locktorture has a factor variable s currently large enough that boosting only happens once every minute or so. Add a tunable to reduce the factor so that boosting happens more often, to test paths and arrive at failure modes earlier. With this change, I can set the factor to like 50 and have the boosting happens every 10 seconds or so. Tested with boot parameters: locktorture.torture_type=mutex_lock locktorture.onoff_interval=1 locktorture.nwriters_stress=8 locktorture.stutter=0 locktorture.rt_boost=1 locktorture.rt_boost_factor=50 locktorture.nlocks=3 Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently RT boosting is only done for rtmutex_lock, however with proxy execution, we also have the mutex_lock participating in priorities. To exercise the testing better, add RT boosting to other lock testing types as well, using a new knob (rt_boost). Tested with boot parameters: locktorture.torture_type=mutex_lock locktorture.onoff_interval=1 locktorture.nwriters_stress=8 locktorture.stutter=0 locktorture.rt_boost=1 locktorture.rt_boost_factor=1 locktorture.nlocks=3 Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Unconditionally log messages corresponding to errors. Acked-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Li Zhijian <zhijianx.li@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
When running locktorture as a module, any lock_torture_init() issues will be reflected in the error code from modprobe or insmod, as the case may be. However, these error codes are not available when running locktorture built-in, for example, when using the kvm.sh script. This commit therefore adds WARN_ON_ONCE() to allow distinguishing lock_torture_init() errors when running locktorture built-in. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, the lock_is_read_held variable is bool, so that a reader sets it to true just after lock acquisition and then to false just before lock release. This works in a rough statistical sense, but can result in false negatives just after one of a pair of concurrent readers has released the lock. This approach does have low overhead, but at the expense of the setting to true potentially never leaving the reader's store buffer, thus resulting in an unconditional false negative. This commit therefore converts this variable to atomic_t and makes the reader use atomic_inc() just after acquisition and atomic_dec() just before release. This does increase overhead, but this increase is negligible compared to the 10-microsecond lock hold time. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The lock_stress_stats structure's ->n_lock_fail and ->n_lock_acquired fields are incremented and sampled locklessly using plain C-language statements, which KCSAN objects to. This commit therefore marks the statistics gathering with data_race() to flag the intent. While in the area, this commit also reduces the number of accesses to the ->n_lock_acquired field, thus eliminating some possible check/use confusion. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The ww_acquire_ctx structure for ww_mutex needs to persist for a complete lock/unlock cycle. In the ww_mutex test in locktorture, however, both ww_acquire_init() and ww_acquire_fini() are called within the lock function only. This causes a lockdep splat of "WARNING: Nested lock was not taken" when lockdep is enabled in the kernel. To fix this problem, we need to move the ww_acquire_fini() after the ww_mutex_unlock() in torture_ww_mutex_unlock(). This is done by allocating a global array of ww_acquire_ctx structures. Each locking thread is associated with its own ww_acquire_ctx via the unique thread id it has so that both the lock and unlock functions can access the same ww_acquire_ctx structure. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210318172814.4400-6-longman@redhat.com
To allow the lock and unlock functions in locktorture to access per-thread information, we need to pass some hint on how to locate those information. One way to do this is to pass in a unique thread id which can then be used to access a global array for thread specific information. Change the lock and unlock method to add a thread id parameter which can be determined by the offset of the lwsp/lrsp pointer from the global lwsa/lrsa array. There is no other functional change in this patch. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210318172814.4400-5-longman@redhat.com
In order to avoid false positive circular locking lockdep splat when runnng the ww_mutex torture test, we need to make sure that the ww_mutexes have the same lock class as the acquire_ctx. This means the ww_mutexes must have the same lockdep key as the acquire_ctx. Unfortunately the current DEFINE_WW_MUTEX() macro fails to do that. As a result, we add an init method for the ww_mutex test to do explicit ww_mutex_init()'s of the ww_mutexes to avoid the false positive warning. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210318172814.4400-3-longman@redhat.com
doc.2021.01.06a: Documentation updates. fixes.2021.01.04b: Miscellaneous fixes. kfree_rcu.2021.01.04a: kfree_rcu() updates. mmdumpobj.2021.01.22a: Dump allocation point for memory blocks. nocb.2021.01.06a: RCU callback offload updates and cblist segment lengths. rt.2021.01.04a: Real-time updates. stall.2021.01.06a: RCU CPU stall warning updates. torture.2021.01.12a: Torture-test updates and polling SRCU grace-period API. tortureall.2021.01.06a: Torture-test script updates.