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2021-07-27rcutorture: Preempt rather than block when testing task stallsPaul E. McKenney
Currently, rcu_torture_stall() does a one-jiffy timed wait when stall_cpu_block is set. This works, but emits a pointless splat in CONFIG_PREEMPT=y kernels. This commit avoids this splat by instead invoking preempt_schedule() in CONFIG_PREEMPT=y kernels. This uses an admittedly ugly #ifdef, but abstracted approaches just looked worse. A prettier approach would provide a preempt_schedule() definition with a WARN_ON() for CONFIG_PREEMPT=n kernels, but this seems quite silly. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-07-04Merge branch 'core-rcu-2021.07.04' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu Pull RCU updates from Paul McKenney: - Bitmap parsing support for "all" as an alias for all bits - Documentation updates - Miscellaneous fixes, including some that overlap into mm and lockdep - kvfree_rcu() updates - mem_dump_obj() updates, with acks from one of the slab-allocator maintainers - RCU NOCB CPU updates, including limited deoffloading - SRCU updates - Tasks-RCU updates - Torture-test updates * 'core-rcu-2021.07.04' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (78 commits) tasks-rcu: Make show_rcu_tasks_gp_kthreads() be static inline rcu-tasks: Make ksoftirqd provide RCU Tasks quiescent states rcu: Add missing __releases() annotation rcu: Remove obsolete rcu_read_unlock() deadlock commentary rcu: Improve comments describing RCU read-side critical sections rcu: Create an unrcu_pointer() to remove __rcu from a pointer srcu: Early test SRCU polling start rcu: Fix various typos in comments rcu/nocb: Unify timers rcu/nocb: Prepare for fine-grained deferred wakeup rcu/nocb: Only cancel nocb timer if not polling rcu/nocb: Delete bypass_timer upon nocb_gp wakeup rcu/nocb: Cancel nocb_timer upon nocb_gp wakeup rcu/nocb: Allow de-offloading rdp leader rcu/nocb: Directly call __wake_nocb_gp() from bypass timer rcu: Don't penalize priority boosting when there is nothing to boost rcu: Point to documentation of ordering guarantees rcu: Make rcu_gp_cleanup() be noinline for tracing rcu: Restrict RCU_STRICT_GRACE_PERIOD to at most four CPUs rcu: Make show_rcu_gp_kthreads() dump rcu_node structures blocking GP ...
2021-06-18sched: Change task_struct::statePeter Zijlstra
Change the type and name of task_struct::state. Drop the volatile and shrink it to an 'unsigned int'. Rename it in order to find all uses such that we can use READ_ONCE/WRITE_ONCE as appropriate. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Acked-by: Will Deacon <will@kernel.org> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Link: https://lore.kernel.org/r/20210611082838.550736351@infradead.org
2021-05-10rcutorture: Move mem_dump_obj() tests into separate functionPaul E. McKenney
To make the purpose of the code more apparent, this commit moves the tests of mem_dump_obj() to a new rcu_torture_mem_dump_obj() function and calls it from rcu_torture_cleanup(). Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10rcutorture: Don't count CPU-stalled time against priority boostingPaul E. McKenney
It will frequently be the case that rcu_torture_boost() will get a ->start_gp_poll() cookie that needs almost all of the current grace period plus an additional grace period to elapse before ->poll_gp_state() will return true. It is quite possible that the current grace period will have (say) two seconds of stall by a CPU failing to pass through a quiescent state, followed by 300 milliseconds of delay due to a preempted reader. The next grace period might suffer only one second of stall by a CPU, followed by another 300 milliseconds of delay due to a preempted reader. This is an example of RCU priority boosting doing its job, but the full elapsed time of 3.6 seconds exceeds the 3.5-second limit. In addition, there is no CPU stall in force at the 3.5-second mark, so this would nevertheless currently be counted as an RCU priority boosting failure. This commit therefore avoids this sort of false positive by resetting the gp_state_time timestamp any time that the current grace period is being blocked by a CPU. This results in extremely frequent calls to the ->check_boost_failed() function, so this commit provides a lockless fastpath that is selected by supplying a NULL CPU-number pointer. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10rcutorture: Forgive RCU boost failures when CPUs don't pass through QSPaul E. McKenney
Currently, rcu_torture_boost() runs CPU-bound at real-time priority to force RCU priority inversions. It then checks that grace periods progress during this CPU-bound time. If grace periods fail to progress, it reports and RCU priority boosting failure. However, it is possible (and sometimes does happen) that the grace period fails to progress due to a CPU failing to pass through a quiescent state for an extended time period (3.5 seconds by default). This can happen due to vCPU preemption, long-running interrupts, and much else besides. There is nothing that RCU priority boosting can do about these situations, and so they should not be counted as RCU priority boosting failures. This commit therefore checks for CPUs (as opposed to preempted tasks) holding up a grace period, and flags the resulting RCU priority boosting failures, but does not splat nor count them as errors. It does rate-limit them to avoid flooding the console log. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10rcutorture: Make rcu_torture_boost_failed() check for GP endPaul E. McKenney
It is possible that a delayed grace period that rcu_torture_boost() was polling for ended while rcu_torture_boost_failed() was printing the failure splat. It would be good to know when this happens. This commit therefore has rcu_torture_boost_failed() recheck the grace period after printing the splat, and printing a message indicating whether or not the grace period has ended. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10rcutorture: Consolidate rcu_torture_boost() timing and statisticsPaul E. McKenney
This commit consolidates two loops in rcu_torture_boost(), one of which counts the number of boost-test episodes and the other of which computes the start time of the next episode, into one loop that does both with but a single acquisition of boost_mutex. This means that the count of the number of boost-test episodes is incremented after an episode completes rather than before it starts, but it also avoids the over-counting that was possible previously. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10rcutorture: Delay-based false positives for RCU priority boosting testsPaul E. McKenney
If an rcu_torture_boost() kthread determines that its grace period has not yet ended, it invokes rcu_torture_boost_failed() which checks whether enough time has elapsed for this to be considered a failure of RCU priority boosting, and, if so, flags the error. Unfortunately, that kthread might be preempted for some seconds between the time that it checks the grace period and the time that it checks the time. This delay can result in a false positive, featuring a complaint that a particular grace period has not ended, followed by a diagnostic dump featuring a much later grace period. This commit avoids these false positives by rechecking for the end of the grace period after the time check. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10rcutorture: Judge RCU priority boosting on grace periods, not callbacksPaul E. McKenney
Currently, rcutorture's testing of RCU priority boosting insists not only that grace periods complete, but also that callbacks be invoked. Although this is in fact what the user would want, ensuring that there is sufficient CPU bandwidth devoted to callback execution is in fact the user's responsibility. One could argue that rcutorture can take on that responsibility, which is true in theory. But in practice, ensuring sufficient CPU bandwidth to ksoftirqd, any rcuc kthreads, and any rcuo kthreads is not particularly consistent with rcutorture's main job, that of stress-testing RCU. In addition, if the system administrator (say) makes very poor choices when pinning rcuo kthreads and then runs rcutorture, there really isn't much rcutorture can do. Besides, RCU priority boosting only boosts lagging readers, not all the machinery required to invoke callbacks in a timely fashion. This commit therefore switches rcutorture's evaluation of RCU priority boosting from callback execution to grace-period completion by using the new start_poll_synchronize_rcu() and poll_state_synchronize_rcu() functions. When rcutorture is built in (as in when there is no innocent workload to inconvenience), the ksoftirqd ktheads are boosted to real-time priority 2 in order to allow timeouts to work properly in the face of rcutorture's testing of RCU priority boosting. Indeed, it is not as easy as it looks to create a reliable test of RCU priority boosting without destroying the rest of the kernel! Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-05-10rcutorture: Abstract read-lock-held checksPaul E. McKenney
This commit adds a (*readlock_held)() function pointer to the rcu_torture_ops structure in order to make the rcu_torture_one_read() function's rcu_dereference_check() lockdep expression more appropriate for a given run. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-03-24Merge branches 'bitmaprange.2021.03.08a', 'fixes.2021.03.15a', ↵Paul E. McKenney
'kvfree_rcu.2021.03.08a', 'mmdumpobj.2021.03.08a', 'nocb.2021.03.15a', 'poll.2021.03.24a', 'rt.2021.03.08a', 'tasks.2021.03.08a', 'torture.2021.03.08a' and 'torturescript.2021.03.22a' into HEAD bitmaprange.2021.03.08a: Allow 3-N for bitmap ranges. fixes.2021.03.15a: Miscellaneous fixes. kvfree_rcu.2021.03.08a: kvfree_rcu() updates. mmdumpobj.2021.03.08a: mem_dump_obj() updates. nocb.2021.03.15a: RCU NOCB CPU updates, including limited deoffloading. poll.2021.03.24a: Polling grace-period interfaces for RCU. rt.2021.03.08a: Realtime-related RCU changes. tasks.2021.03.08a: Tasks-RCU updates. torture.2021.03.08a: Torture-test updates. torturescript.2021.03.22a: Torture-test scripting updates.
2021-03-24rcutorture: Test start_poll_synchronize_rcu() and poll_state_synchronize_rcu()Paul E. McKenney
This commit causes rcutorture to test the new start_poll_synchronize_rcu() and poll_state_synchronize_rcu() functions. Because of the difficulty of determining the nature of a synchronous RCU grace (expedited or not), the test that insisted that poll_state_synchronize_rcu() detect an intervening synchronize_rcu() had to be dropped. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-03-08rcutorture: Replace rcu_torture_stall string with %sStephen Zhang
This commit replaces a hard-coded "rcu_torture_stall" string in a pr_alert() format with "%s" and __func__. Signed-off-by: Stephen Zhang <stephenzhangzsd@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-03-08rcutorture: Fix testing of RCU priority boostingPaul E. McKenney
Currently, rcutorture refuses to test RCU priority boosting in CONFIG_HOTPLUG_CPU=y kernels, which are the only kind normally built on x86 these days. This commit therefore updates rcutorture's tests of RCU priority boosting to make them safe for CPU hotplug. However, these tests will fail unless TIMER_SOFTIRQ runs at realtime priority, which does not happen in current mainline. This commit therefore also refuses to test RCU priority boosting except in kernels built with CONFIG_PREEMPT_RT=y. While in the area, this commt adds some debug output at boost-fail time that helps diagnose the cause of the failure, for example, failing to run TIMER_SOFTIRQ at realtime priority. Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Scott Wood <swood@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-03-08rcutorture: Add crude tests for mem_dump_obj()Paul E. McKenney
This commit adds a few crude tests for mem_dump_obj() to rcutorture runs. Just to prevent bitrot, you understand! Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-22Merge branches 'doc.2021.01.06a', 'fixes.2021.01.04b', ↵Paul E. McKenney
'kfree_rcu.2021.01.04a', 'mmdumpobj.2021.01.22a', 'nocb.2021.01.06a', 'rt.2021.01.04a', 'stall.2021.01.06a', 'torture.2021.01.12a' and 'tortureall.2021.01.06a' into HEAD 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.
2021-01-06torture: Maintain torture-specific set of CPUs-online booksPaul E. McKenney
The TREE01 rcutorture scenario intentionally creates confusion as to the number of available CPUs by specifying the "maxcpus=8 nr_cpus=43" kernel boot parameters. This can disable rcutorture's load shedding, which currently uses num_online_cpus(), which would count the extra 35 CPUs. However, the rcutorture guest OS will be provisioned with only 8 CPUs, which means that rcutorture will present full load even when all but one of the original 8 CPUs are offline. This can result in spurious errors due to extreme overloading of that single remaining CPU. This commit therefore keeps a separate set of books on the number of usable online CPUs, so that torture_num_online_cpus() is used for load shedding instead of num_online_cpus(). Note that initial sizing must use num_online_cpus() because torture_num_online_cpus() will return NR_CPUS until shortly after torture_onoff_init() is invoked. Reported-by: Frederic Weisbecker <frederic@kernel.org> [ paulmck: Apply feedback from kernel test robot. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06rcutorture: Make object_debug also double call_rcu() heap objectPaul E. McKenney
This commit provides a test for call_rcu() printing the allocation address of a double-freed callback by double-freeing a callback allocated via kmalloc(). However, this commit does not depend on any other commit. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06rcutorture: Use hrtimers for reader and writer delaysPaul E. McKenney
This commit replaces schedule_timeout_uninterruptible() and schedule_timeout_interruptible() with torture_hrtimeout_us() and torture_hrtimeout_jiffies() to avoid timer-wheel synchronization. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06rcutorture: Use torture_hrtimeout_jiffies() to avoid busy-waitsPaul E. McKenney
Because rcu_torture_writer() and rcu_torture_fakewriter() predate hrtimers, they do timer-wheel-decoupled timed waits by using the timer-wheel-based schedule_timeout_interruptible() functions in conjunction with a random udelay()-based wait. This latter unnecessarily burns CPU time, so this commit instead uses torture_hrtimeout_jiffies() to decouple from the timer wheels without busy-waiting. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06rcutorture: Make rcu_torture_fakewriter() use blocking wait primitivesPaul E. McKenney
Full testing of the new SRCU polling API requires that the fake writers also use it in order to test concurrent calls to all of the API members, especially start_poll_synchronize_srcu(). This commit makes rcu_torture_fakewriter() use all available blocking grace-period-wait primitives available from the RCU flavor under test. Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/ Reported-by: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06rcutorture: Make synctype[] and nsynctype be static globalPaul E. McKenney
Full testing of the new SRCU polling API requires that the fake writers also use it in order to test concurrent calls to all of the API members, especially start_poll_synchronize_srcu(). This commit prepares the ground for this by making the synctype[] and nsynctype variables be static globals so that the rcu_torture_fakewriter() function can access them. Initialization of these variables is moved from rcu_torture_writer() to a new rcu_torture_write_types() function that is invoked from rcu_torture_init() just before the first writer kthread is spawned. Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/ Reported-by: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06rcutorture: Require entire stutter period be post-bootPaul E. McKenney
Currently, the rcu_torture_writer() function checks that all required grace periods elapse during a stutter interval, which is a multi-second time period during which the test load is removed. However, this check is suppressed during early boot (that is, before init is spawned) in order to avoid false positives that otherwise occur due to heavy load on the single boot CPU. Unfortunately, this approach is insufficient. It is possible that the stutter interval might end just as init is spawned, so that early boot conditions prevailed during almost the entire stutter interval. This commit therefore takes a snapshot of boot-complete state just before the stutter interval, thus suppressing the check for failure to complete grace periods unless the entire stutter interval took place after early boot. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06rcu/nocb: Code-style nits in callback-offloading togglingPaul E. McKenney
This commit addresses a few code-style nits in callback-offloading toggling, including one that predates this toggling. Cc: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-06rcutorture: Test runtime toggling of CPUs' callback offloadingPaul E. McKenney
Frederic Weisbecker is adding the ability to change the rcu_nocbs state of CPUs at runtime, that is, to offload and deoffload their RCU callback processing without the need to reboot. As the old saying goes, "if it ain't tested, it don't work", so this commit therefore adds prototype rcutorture testing for this capability. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Frederic Weisbecker <frederic@kernel.org>
2021-01-04rcutorture: Add testing for RCU's global memory orderingPaul E. McKenney
RCU guarantees that anything seen by a given reader will also be seen after any grace period that must wait on that reader. This is very likely to hold based on inspection, but the advantage of having rcutorture do the inspecting is that rcutorture doesn't mind inspecting frequently and often. This commit therefore adds code to test RCU's global memory ordering. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-04rcutorture: Add reader-side tests of polling grace-period APIPaul E. McKenney
This commit adds reader-side testing of the polling grace-period API. This testing verifies that a cookie obtained in an SRCU read-side critical section does not get a true return from poll_state_synchronize_srcu() within that same critical section. Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/ Reported-by: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-04rcutorture: Add writer-side tests of polling grace-period APIPaul E. McKenney
This commit adds writer-side testing of the polling grace-period API. One test verifies that the polling API sees a grace period caused by some other mechanism. Another test verifies that using the polling API to wait for a grace period does not result in too-short grace periods. A third test verifies that the polling API does not report completion within a read-side critical section. A fourth and final test verifies that the polling API does report completion given an intervening grace period. Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/ Reported-by: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-01-04rcutorture: Prepare for ->start_gp_poll and ->poll_gp_statePaul E. McKenney
The new get_state_synchronize_srcu(), start_poll_synchronize_srcu() and poll_state_synchronize_srcu() functions need to be tested, and so this commit prepares by renaming the rcu_torture_ops field ->get_state to ->get_gp_state in order to be consistent with the upcoming ->start_gp_poll and ->poll_gp_state fields. Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/ Reported-by: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-19Merge branches 'cpuinfo.2020.11.06a', 'doc.2020.11.06a', ↵Paul E. McKenney
'fixes.2020.11.19b', 'lockdep.2020.11.02a', 'tasks.2020.11.06a' and 'torture.2020.11.06a' into HEAD cpuinfo.2020.11.06a: Speedups for /proc/cpuinfo. doc.2020.11.06a: Documentation updates. fixes.2020.11.19b: Miscellaneous fixes. lockdep.2020.11.02a: Lockdep-RCU updates to avoid "unused variable". tasks.2020.11.06a: Tasks-RCU updates. torture.2020.11.06a': Torture-test updates.
2020-11-06rcutorture: Don't do need_resched() testing if ->sync is NULLPaul E. McKenney
If cur_ops->sync is NULL, rcu_torture_fwd_prog_nr() will nevertheless attempt to call through it. This commit therefore flags cases where neither need_resched() nor call_rcu() forward-progress testing can be performed due to NULL function pointers, and also causes rcu_torture_fwd_prog_nr() to take an early exit if cur_ops->sync() is NULL. Reported-by: Tom Rix <trix@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-06rcutorture: Small code cleanupsPaul E. McKenney
The rcu_torture_cleanup() function fails to NULL out the reader_tasks pointer after freeing it and its fakewriter_tasks loop has redundant braces. This commit therefore cleans these up. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-06rcutorture: Make stutter_wait() caller restore priorityPaul E. McKenney
Currently, stutter_wait() will happily spin waiting for the stutter interval to end even if the caller is running at a real-time priority level. This could starve normal-priority tasks for no good reason. This commit therefore drops the calling task's priority to SCHED_OTHER MAX_NICE if stutter_wait() needs to wait. But when it waits, stutter_wait() returns true, which allows the caller to restore the priority if needed. Callers that were already running at SCHED_OTHER MAX_NICE obviously do not need any changes, but this commit also restores priority for higher-priority callers. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-06rcutorture: Prevent hangs for invalid argumentsPaul E. McKenney
If an rcutorture torture-test run is given a bad kvm.sh argument, the test will complain to the console, which is good. What is bad is that from the user's perspective, it will just hang for the time specified by the --duration argument. This commit therefore forces an immediate kernel shutdown if a rcu_torture_init()-time error occurs, thus avoiding the appearance of a hang. It also forces a console splat in this case to clearly indicate the presence of an error. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-02rcutorture: Make grace-period kthread report match RCU flavor being testedPaul E. McKenney
At the end of the test and after rcu_torture_writer() stalls, rcutorture invokes show_rcu_gp_kthreads() in order to dump out information on the RCU grace-period kthread. This makes a lot of sense when testing vanilla RCU, but not so much for the other flavors. This commit therefore allows per-flavor kthread-dump functions to be specified. [ paulmck: Apply feedback from kernel test robot <lkp@intel.com>. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24rcutorture: Allow pointer leaks to test diagnostic codePaul E. McKenney
This commit adds an rcutorture.leakpointer module parameter that intentionally leaks an RCU-protected pointer out of the RCU read-side critical section and checks to see if the corresponding grace period has elapsed, emitting a WARN_ON_ONCE() if so. This module parameter can be used to test facilities like CONFIG_RCU_STRICT_GRACE_PERIOD that end grace periods quickly. While in the area, also document rcutorture.irqreader, which was previously left out. Reported-by Jann Horn <jannh@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24rcutorture: Hoist OOM registry up one levelPaul E. McKenney
Currently, registering and unregistering the OOM notifier is done right before and after the test, respectively. This will not work well for multi-threaded tests, so this commit hoists this registering and unregistering up into the rcu_torture_fwd_prog_init() and rcu_torture_fwd_prog_cleanup() functions. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24rcutorture: Properly synchronize with OOM notifierPaul E. McKenney
The current rcutorture forward-progress code assumes that it is the only cause of out-of-memory (OOM) events. For script-based rcutorture testing, this assumption is in fact correct. However, testing based on modprobe/rmmod might well encounter external OOM events, which could happen at any time. This commit therefore properly synchronizes the interaction between rcutorture's forward-progress testing and its OOM notifier by adding a global mutex. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24rcutorture: Properly set rcu_fwds for OOM handlingPaul E. McKenney
The conversion of rcu_fwds to dynamic allocation failed to actually allocate the required structure. This commit therefore allocates it, frees it, and updates rcu_fwds accordingly. While in the area, it abstracts the cleanup actions into rcu_torture_fwd_prog_cleanup(). Fixes: 5155be9994e5 ("rcutorture: Dynamically allocate rcu_fwds structure") Reported-by: kernel test robot <rong.a.chen@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24rcutorture: Output number of elapsed grace periodsJoel Fernandes (Google)
This commit adds code to print the grace-period number at the start of the test along with both the grace-period number and the number of elapsed grace periods at the end of the test. Note that variants of RCU)without the notion of a grace-period number (for example, Tiny RCU) just print zeroes. [ paulmck: Adjust commit log. ] Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24rcutorture: Remove KCSAN stubsPaul E. McKenney
KCSAN is now in mainline, so this commit removes the stubs for the data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS() macros. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-06Merge tag 'sched-fifo-2020-08-04' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull sched/fifo updates from Ingo Molnar: "This adds the sched_set_fifo*() encapsulation APIs to remove static priority level knowledge from non-scheduler code. The three APIs for non-scheduler code to set SCHED_FIFO are: - sched_set_fifo() - sched_set_fifo_low() - sched_set_normal() These are two FIFO priority levels: default (high), and a 'low' priority level, plus sched_set_normal() to set the policy back to non-SCHED_FIFO. Since the changes affect a lot of non-scheduler code, we kept this in a separate tree" * tag 'sched-fifo-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) sched,tracing: Convert to sched_set_fifo() sched: Remove sched_set_*() return value sched: Remove sched_setscheduler*() EXPORTs sched,psi: Convert to sched_set_fifo_low() sched,rcutorture: Convert to sched_set_fifo_low() sched,rcuperf: Convert to sched_set_fifo_low() sched,locktorture: Convert to sched_set_fifo() sched,irq: Convert to sched_set_fifo() sched,watchdog: Convert to sched_set_fifo() sched,serial: Convert to sched_set_fifo() sched,powerclamp: Convert to sched_set_fifo() sched,ion: Convert to sched_set_normal() sched,powercap: Convert to sched_set_fifo*() sched,spi: Convert to sched_set_fifo*() sched,mmc: Convert to sched_set_fifo*() sched,ivtv: Convert to sched_set_fifo*() sched,drm/scheduler: Convert to sched_set_fifo*() sched,msm: Convert to sched_set_fifo*() sched,psci: Convert to sched_set_fifo*() sched,drbd: Convert to sched_set_fifo*() ...
2020-06-29Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', ↵Paul E. McKenney
'kfree_rcu.2020.06.29a', 'rcu-tasks.2020.06.29a', 'scale.2020.06.29a', 'srcu.2020.06.29a' and 'torture.2020.06.29a' into HEAD doc.2020.06.29a: Documentation updates. fixes.2020.06.29a: Miscellaneous fixes. kfree_rcu.2020.06.29a: kfree_rcu() updates. rcu-tasks.2020.06.29a: RCU Tasks updates. scale.2020.06.29a: Read-side scalability tests. srcu.2020.06.29a: SRCU updates. torture.2020.06.29a: Torture-test updates.
2020-06-29rcutorture: Check for unwatched readersPaul E. McKenney
RCU is supposed to be watching all non-idle kernel code and also all softirq handlers. This commit adds some teeth to this statement by adding a WARN_ON_ONCE(). Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-29rcu/rcutorture: Replace 0 with falseJules Irenge
Coccinelle reports a warning WARNING: Assignment of 0/1 to bool variable The root cause is that the variable lastphase is a bool, but is initialised with integer 0. This commit therefore replaces the 0 with a false. Signed-off-by: Jules Irenge <jbi.octave@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-29rcutorture: NULL rcu_torture_current earlier in cleanup codePaul E. McKenney
Currently, the rcu_torture_current variable remains non-NULL until after all readers have stopped. During this time, rcu_torture_stats_print() will think that the test is still ongoing, which can result in confusing dmesg output. This commit therefore NULLs rcu_torture_current immediately after the rcu_torture_writer() kthread has decided to stop, thus informing rcu_torture_stats_print() much sooner. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-29rcutorture: Add races with task-exit processingPaul E. McKenney
Several variants of Linux-kernel RCU interact with task-exit processing, including preemptible RCU, Tasks RCU, and Tasks Trace RCU. This commit therefore adds testing of this interaction to rcutorture by adding rcutorture.read_exit_burst and rcutorture.read_exit_delay kernel-boot parameters. These kernel parameters control the frequency and spacing of special read-then-exit kthreads that are spawned. [ paulmck: Apply feedback from Dan Carpenter's static checker. ] [ paulmck: Reduce latency to avoid false-positive shutdown hangs. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-29docs: RCU: Convert torture.txt to ReSTMauro Carvalho Chehab
- Add a SPDX header; - Adjust document and section titles; - Some whitespace fixes and new line breaks; - Mark literal blocks as such; - Add it to RCU/index.rst. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-15sched: Remove sched_set_*() return valuePeter Zijlstra
Ingo suggested that since the new sched_set_*() functions are implemented using the 'nocheck' variants, they really shouldn't ever fail, so remove the return value. Cc: axboe@kernel.dk Cc: daniel.lezcano@linaro.org Cc: sudeep.holla@arm.com Cc: airlied@redhat.com Cc: broonie@kernel.org Cc: paulmck@kernel.org Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org>