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* rcutorture: Allow pointer leaks to test diagnostic codePaul E. McKenney2020-08-241-0/+4
| | | | | | | | | | | | | | | 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>
* rcutorture: Hoist OOM registry up one levelPaul E. McKenney2020-08-241-2/+2
| | | | | | | | | | 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>
* rcutorture: Properly synchronize with OOM notifierPaul E. McKenney2020-08-241-1/+13
| | | | | | | | | | | | | | 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>
* rcutorture: Properly set rcu_fwds for OOM handlingPaul E. McKenney2020-08-241-1/+12
| | | | | | | | | | | 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>
* rcutorture: Output number of elapsed grace periodsJoel Fernandes (Google)2020-08-241-2/+11
| | | | | | | | | | | | 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>
* rcutorture: Remove KCSAN stubsPaul E. McKenney2020-08-241-13/+0
| | | | | | | | 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>
* Merge tag 'sched-fifo-2020-08-04' of ↵Linus Torvalds2020-08-061-6/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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*() ...
| * sched: Remove sched_set_*() return valuePeter Zijlstra2020-06-151-4/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * sched,rcutorture: Convert to sched_set_fifo_low()Peter Zijlstra2020-06-151-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Because SCHED_FIFO is a broken scheduler model (see previous patches) take away the priority field, the kernel can't possibly make an informed decision. Effectively no change. Cc: paulmck@kernel.org Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
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*-. \ Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', ↵Paul E. McKenney2020-06-291-5/+112
|\ \ \ | | |/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | '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.
| | * rcutorture: Check for unwatched readersPaul E. McKenney2020-06-291-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * rcu/rcutorture: Replace 0 with falseJules Irenge2020-06-291-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * rcutorture: NULL rcu_torture_current earlier in cleanup codePaul E. McKenney2020-06-291-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * rcutorture: Add races with task-exit processingPaul E. McKenney2020-06-291-3/+109
| |/ | | | | | | | | | | | | | | | | | | | | | | | | 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>
* / docs: RCU: Convert torture.txt to ReSTMauro Carvalho Chehab2020-06-291-1/+1
|/ | | | | | | | | | | - 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>
*-. Merge branches 'fixes.2020.04.27a', 'kfree_rcu.2020.04.27a', ↵Paul E. McKenney2020-05-071-22/+133
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | 'rcu-tasks.2020.04.27a', 'stall.2020.04.27a' and 'torture.2020.05.07a' into HEAD fixes.2020.04.27a: Miscellaneous fixes. kfree_rcu.2020.04.27a: Changes related to kfree_rcu(). rcu-tasks.2020.04.27a: Addition of new RCU-tasks flavors. stall.2020.04.27a: RCU CPU stall-warning updates. torture.2020.05.07a: Torture-test updates.
| | * rcutorture: Convert ULONG_CMP_LT() to time_before()Paul E. McKenney2020-05-071-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | This commit converts three ULONG_CMP_LT() invocations in rcutorture to time_before() to reflect the fact that they are comparing timestamps to the jiffies counter. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | * rcutorture: Make rcu_fwds and rcu_fwd_emergency_stop staticJason Yan2020-05-071-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit fixes the following sparse warning: kernel/rcu/rcutorture.c:1695:16: warning: symbol 'rcu_fwds' was not declared. Should it be static? kernel/rcu/rcutorture.c:1696:6: warning: symbol 'rcu_fwd_emergency_stop' was not declared. Should it be static? Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Jason Yan <yanaijie@huawei.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | * rcu: Allow rcutorture to starve grace-period kthreadPaul E. McKenney2020-05-071-3/+15
| | | | | | | | | | | | | | | | | | | | | | | | This commit provides an rcutorture.stall_gp_kthread module parameter to allow rcutorture to starve the grace-period kthread. This allows testing the code that detects such starvation. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | * rcutorture: Add flag to produce non-busy-wait task stallsPaul E. McKenney2020-05-071-6/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit aids testing of RCU task stall warning messages by adding an rcutorture.stall_cpu_block module parameter that results in the induced stall sleeping within the RCU read-side critical section. Spinning with interrupts disabled is still available via the rcutorture.stall_cpu_irqsoff module parameter, and specifying neither of these two module parameters will spin with preemption disabled. Note that sleeping (as opposed to preemption) results in additional complaints from RCU at context-switch time, so yet more testing. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | * rcutorture: Mark data-race potential for rcu_barrier() test statisticsPaul E. McKenney2020-04-271-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The n_barrier_successes, n_barrier_attempts, and n_rcu_torture_barrier_error variables are updated (without access markings) by the main rcu_barrier() test kthread, and accessed (also without access markings) by the rcu_torture_stats() kthread. This of course can result in KCSAN complaints. Because the accesses are in diagnostic prints, this commit uses data_race() to excuse the diagnostic prints from the data race. If this were to ever cause bogus statistics prints (for example, due to store tearing), any misleading information would be disambiguated by the presence or absence of an rcutorture splat. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely and due to the mild consequences of the failure, namely a confusing rcutorture console message. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
| | * rcutorture: Add KCSAN stubsPaul E. McKenney2020-04-271-0/+12
| |/ |/| | | | | | | | | | | | | This commit adds stubs for KCSAN's data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS() macros to allow code using these macros to move ahead. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| * rcutorture: Add torture tests for RCU Tasks TracePaul E. McKenney2020-04-271-1/+43
| | | | | | | | | | | | | | This commit adds the definitions required to torture the tracing flavor of RCU tasks. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| * rcutorture: Add torture tests for RCU Tasks RudePaul E. McKenney2020-04-271-2/+29
| | | | | | | | | | | | | | This commit adds the definitions required to torture the rude flavor of RCU tasks. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| * rcutorture: Add a test for synchronize_rcu_mult()Paul E. McKenney2020-04-271-2/+7
| | | | | | | | | | | | | | This commit adds a crude test for synchronize_rcu_mult(). This is currently a smoke test rather than a high-quality stress test. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| * rcutorture: Add test of holding scheduler locks across rcu_read_unlock()Paul E. McKenney2020-04-271-1/+9
|/ | | | | | | | | | | | | | | Now that it should be safe to hold scheduler locks across rcu_read_unlock(), even in cases where the corresponding RCU read-side critical section might have been preempted and boosted, the commit adds a test of this capability to rcutorture. This has been tested on current mainline (which can deadlock in this situation), and lockdep duly reported the expected deadlock. On -rcu, lockdep is silent, thus far, anyway. Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcutorture: Manually clean up after rcu_barrier() failurePaul E. McKenney2020-02-201-1/+15
| | | | | | | | | | | | | | | | | Currently, if rcu_barrier() returns too soon, the test waits 100ms and then does another instance of the test. However, if rcu_barrier() were to have waited for more than 100ms too short a time, this could cause the test's rcu_head structures to be reused while they were still on RCU's callback lists. This can result in knock-on errors that obscure the original rcu_barrier() test failure. This commit therefore adds code that attempts to wait until all of the test's callbacks have been invoked. Of course, if RCU completely lost track of the corresponding rcu_head structures, this wait could be forever. This commit therefore also complains if this attempted recovery takes more than one second, and it also gives up when the test ends. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcutorture: Make rcu_torture_barrier_cbs() post from corresponding CPUPaul E. McKenney2020-02-201-3/+13
| | | | | | | | | | | | | | Currently, rcu_torture_barrier_cbs() posts callbacks from whatever CPU it is running on, which means that all these kthreads might well be posting from the same CPU, which would drastically reduce the effectiveness of this test. This commit therefore uses IPIs to make the callbacks be posted from the corresponding CPU (given by local variable myid). If the IPI fails (which can happen if the target CPU is offline or does not exist at all), the callback is posted on whatever CPU is currently running. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcutorture: Annotation lockless accesses to rcu_torture_currentPaul E. McKenney2020-02-201-4/+6
| | | | | | | | | | | The rcutorture global variable rcu_torture_current is accessed locklessly, so it must use the RCU pointer load/store primitives. This commit therefore adds several that were missed. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely and due to this being used only by rcutorture. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcutorture: Add READ_ONCE() to rcu_torture_count and rcu_torture_batchPaul E. McKenney2020-02-201-2/+2
| | | | | | | | | | | The rcutorture rcu_torture_count and rcu_torture_batch per-CPU variables are read locklessly, so this commit adds the READ_ONCE() to a load in order to avoid various types of compiler vandalism^Woptimization. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely and due to this being rcutorture. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcutorture: Fix stray access to rcu_fwd_cb_nodelayPaul E. McKenney2020-02-201-1/+1
| | | | | | | | | | | | | The rcu_fwd_cb_nodelay variable suppresses excessively long read-side delays while carrying out an rcutorture forward-progress test. As such, it is accessed both by readers and updaters, and most of the accesses therefore use *_ONCE(). Except for one in rcu_read_delay(), which this commit fixes. This data race was reported by KCSAN. Not appropriate for backporting due to this being rcutorture. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcutorture: Fix rcu_torture_one_read()/rcu_torture_writer() data racePaul E. McKenney2020-02-201-4/+6
| | | | | | | | | | | | The ->rtort_pipe_count field in the rcu_torture structure checks for too-short grace periods, and is therefore read by rcutorture's readers while being updated by rcutorture's writers. This commit therefore adds the needed READ_ONCE() and WRITE_ONCE() invocations. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely and due to this being rcutorture. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcutorture: Suppress boottime bad-sequence warningsPaul E. McKenney2020-02-201-1/+2
| | | | | | | | | | | | | | In normal production, an excessively long wait on a grace period (synchronize_rcu(), for example) at boottime is often just as bad as at any other time. In fact, given the desire for fast boot, any sort of long wait at boot is a bad idea. However, heavy rcutorture testing on large hyperthreaded systems can generate such long waits during boot as a matter of course. This commit therefore causes the rcupdate.rcu_cpu_stall_suppress_at_boot kernel boot parameter to suppress reporting of bootime bad-sequence warning due to excessively long grace-period waits. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcutorture: Allow boottime stall warnings to be suppressedPaul E. McKenney2020-02-201-1/+1
| | | | | | | | | | | | In normal production, an RCU CPU stall warning at boottime is often just as bad as at any other time. In fact, given the desire for fast boot, any sort of long-term stall at boot is a bad idea. However, heavy rcutorture testing on large hyperthreaded systems can generate boottime RCU CPU stalls as a matter of course. This commit therefore provides a kernel boot parameter that suppresses reporting of boottime RCU CPU stall warnings and similarly of rcutorture writer stalls. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcutorture: Refrain from callback flooding during bootPaul E. McKenney2020-02-201-2/+5
| | | | | | | | | | | | | | | | | Additional rcutorture aggression can result in, believe it or not, boot times in excess of three minutes on large hyperthreaded systems. This is long enough for rcutorture to decide to do some callback flooding, which seems a bit excessive given that userspace cannot have started until long after boot, and it is userspace that does the real-world callback flooding. Worse yet, because Tiny RCU lacks forward-progress functionality, the looping-in-the-kernel tests can also be problematic during early boot. This commit therefore causes rcutorture to hold off on callback flooding until about the time that init is spawned, and the same for looping-in-the-kernel tests for Tiny RCU. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcutorture: Suppress forward-progress complaints during early bootPaul E. McKenney2020-02-201-1/+2
| | | | | | | | | | | | | | | | | | Some larger systems can take in excess of 50 seconds to complete their early boot initcalls prior to spawing init. This does not in any way help the forward-progress judgments of built-in rcutorture (when rcutorture is built as a module, the insmod or modprobe command normally cannot happen until some time after boot completes). This commit therefore suppresses such complaints until about the time that init is spawned. This also includes a fix to a stupid error located by kbuild test robot. [ paulmck: Apply kbuild test robot feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org> [ paulmck: Fix to nohz_full slow-expediting recovery logic, per bpetkov. ] [ paulmck: Restrict splat to CONFIG_PREEMPT_RT=y kernels and simplify. ] Tested-by: Borislav Petkov <bp@alien8.de>
*-. Merge branches 'doc.2019.12.10a', 'exp.2019.12.09a', 'fixes.2020.01.24a', ↵Paul E. McKenney2020-01-241-60/+81
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'kfree_rcu.2020.01.24a', 'list.2020.01.10a', 'preempt.2020.01.24a' and 'torture.2019.12.09a' into HEAD doc.2019.12.10a: Documentations updates exp.2019.12.09a: Expedited grace-period updates fixes.2020.01.24a: Miscellaneous fixes kfree_rcu.2020.01.24a: Batch kfree_rcu() work list.2020.01.10a: RCU-protected-list updates preempt.2020.01.24a: Preemptible RCU updates torture.2019.12.09a: Torture-test updates
| | * rcutorture: Dynamically allocate rcu_fwds structurePaul E. McKenney2019-12-091-5/+8
| | | | | | | | | | | | | | | | | | | | | | | | This commit switches from static structure to dynamic allocation for rcu_fwds as another step towards providing multiple call_rcu() forward-progress kthreads. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | * rcutorture: Complete threading rcu_fwd pointers through functionsPaul E. McKenney2019-12-091-18/+21
| | | | | | | | | | | | | | | | | | | | | | | | This commit threads pointers to rcu_fwd structures through the remaining functions using rcu_fwds directly, namely rcu_torture_fwd_prog_cbfree(), rcutorture_oom_notify() and rcu_torture_fwd_prog_init(). Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | * rcutorture: Move to dynamic initialization of rcu_fwdsPaul E. McKenney2019-12-091-5/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | In order to add multiple call_rcu() forward-progress kthreads, it will be necessary to dynamically allocate and initialize. This commit therefore moves the initialization from compile time to instead immediately precede thread-creation time. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | * rcutorture: Thread rcu_fwd pointer through forward-progress functionsPaul E. McKenney2019-12-091-37/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to add multiple kthreads, it will be necessary to allow the various functions to operate on a pointer to their kthread's rcu_fwd structure. This commit therefore starts the process of adding the needed "struct rcu_fwd" parameters and arguments to the various callback forward-progress functions. Note that rcutorture_oom_notify() and rcu_torture_fwd_cb_hist() will eventually need to iterate over all kthreads' rcu_fwd structures. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | * rcutorture: Pull callback forward-progress data into rcu_fwd structPaul E. McKenney2019-12-091-45/+58
| |/ |/| | | | | | | | | | | | | | | Now that RCU behaves reasonably well with the current single-kthread call_rcu() forward-progress testing, it is time to add more kthreads. This commit takes a first step towards that goal by wrapping what will be the per-kthread data into a new rcu_fwd structure. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| * rcu: Use CONFIG_PREEMPTION where appropriateSebastian Andrzej Siewior2019-12-091-1/+1
|/ | | | | | | | | | | | | | | | | | | | | The config option `CONFIG_PREEMPT' is used for the preemption model "Low-Latency Desktop". The config option `CONFIG_PREEMPTION' is enabled when kernel preemption is enabled which is true for the preemption model `CONFIG_PREEMPT' and `CONFIG_PREEMPT_RT'. Use `CONFIG_PREEMPTION' if it applies to both preemption models and not just to `CONFIG_PREEMPT'. Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: rcu@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
*-. Merge branches 'doc.2019.10.29a', 'fixes.2019.10.30a', 'nohz.2019.10.28a', ↵Paul E. McKenney2019-10-301-13/+31
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'replace.2019.10.30a', 'torture.2019.10.05a' and 'lkmm.2019.10.05a' into HEAD doc.2019.10.29a: RCU documentation updates. fixes.2019.10.30a: RCU miscellaneous fixes. nohz.2019.10.28a: RCU NO_HZ and NO_HZ_FULL updates. replace.2019.10.30a: Replace rcu_swap_protected() with rcu_replace(). torture.2019.10.05a: RCU torture-test updates. lkmm.2019.10.05a: Linux kernel memory model updates.
| | * rcutorture: Make in-kernel-loop testing more brutalPaul E. McKenney2019-10-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rcu_torture_fwd_prog_nr() tests the ability of RCU to tolerate in-kernel busy loops. It invokes rcu_torture_fwd_prog_cond_resched() within its delay loop, which, in PREEMPT && NO_HZ_FULL kernels results in the occasional direct call to schedule(). Now, this direct call to schedule() is appropriate for call_rcu() flood testing, in which either the kernel should restrain itself or userspace transitions will supply the needed restraint. But in pure in-kernel loops, the occasional cond_resched() should do the job. This commit therefore makes rcu_torture_fwd_prog_nr() use cond_resched() instead of rcu_torture_fwd_prog_cond_resched() in order to increase the brutality of this aspect of rcutorture testing. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | * rcutorture: Separate warnings for each failure typePaul E. McKenney2019-10-051-6/+9
| |/ |/| | | | | | | | | | | | | | | | | | | | | Currently, each of six different types of failure triggers a single WARN_ON_ONCE(), and it is then necessary to stare at the rcu_torture_stats(), Reader Pipe, and Reader Batch lines looking for inappropriately non-zero values. This can be annoying and error-prone, so this commit provides a separate WARN_ON_ONCE() for each of the six error conditions and adds short comments to each to ease error identification. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| * rcutorture: Emulate dyntick aspect of userspace nohz_full sojournPaul E. McKenney2019-10-051-0/+11
| | | | | | | | | | | | | | | | | | During an actual call_rcu() flood, there would be frequent trips to userspace (in-kernel call_rcu() floods must be otherwise housebroken). Userspace execution on nohz_full CPUs implies an RCU dyntick idle/not-idle transition pair, so this commit adds emulation of that pair. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| * rcutorture: Force on tick for readers and callback floodersPaul E. McKenney2019-10-051-6/+10
|/ | | | | | | | | | | | | | | Readers and callback flooders in the rcutorture stress-test suite run for extended time periods by design. They do take pains to relinquish the CPU from time to time, but in some cases this relies on the scheduler being active, which in turn relies on the scheduler-clock interrupt firing from time to time. This commit therefore forces scheduling-clock interrupts within these loops. While in the area, this commit also prevents rcu_torture_reader()'s occasional timed sleeps from delaying shutdown. [ paulmck: Apply Joel Fernandes TICK_DEP_MASK_RCU->TICK_DEP_BIT_RCU fix. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcu/nocb: Print no-CBs diagnostics when rcutorture writer unduly delayedPaul E. McKenney2019-08-131-0/+1
| | | | | | | | This commit causes locking, sleeping, and callback state to be printed for no-CBs CPUs when the rcutorture writer is delayed sufficiently for rcutorture to complain. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* rcutorture: Aggressive forward-progress tests shouldn't block shutdownPaul E. McKenney2019-08-011-1/+16
| | | | | | | | The more aggressive forward-progress tests can interfere with rcutorture shutdown, resulting in false-positive diagnostics. This commit therefore ends any such tests 30 seconds prior to shutdown. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
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