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2024-11-12rcutorture: Test start-poll primitives with interrupts disabledPaul E. McKenney
This commit tests the ->start_poll() and ->start_poll_full() functions with interrupts disabled, but only for RCU variants setting the ->start_poll_irqsoff flag. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
2024-11-12rcutorture: Add srcu_read_lock_lite() support to rcutorture.reader_flavorPaul E. McKenney
This commit causes bit 0x4 of rcutorture.reader_flavor to select the new srcu_read_lock_lite() and srcu_read_unlock_lite() functions. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: <bpf@vger.kernel.org> Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
2024-11-12rcutorture: Add reader_flavor parameter for SRCU readersPaul E. McKenney
This commit adds an rcutorture.reader_flavor parameter whose bits correspond to reader flavors. For example, SRCU's readers are 0x1 for normal and 0x2 for NMI-safe. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: <bpf@vger.kernel.org> Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
2024-11-12rcutorture: Expand RCUTORTURE_RDR_MASK_[12] to eight bitsPaul E. McKenney
This commit prepares for testing of multiple SRCU reader flavors by expanding RCUTORTURE_RDR_MASK_1 and RCUTORTURE_RDR_MASK_2 from a single bit to eight bits, allowing them to accommodate the return values from multiple calls to srcu_read_lock*(). This will in turn permit better testing coverage for these SRCU reader flavors, including testing of the diagnostics for inproper use of mixed reader flavors. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: <bpf@vger.kernel.org> Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
2024-11-07softirq: Use a dedicated thread for timer wakeups on PREEMPT_RT.Sebastian Andrzej Siewior
The timer and hrtimer soft interrupts are raised in hard interrupt context. With threaded interrupts force enabled or on PREEMPT_RT this leads to waking the ksoftirqd for the processing of the soft interrupt. ksoftirqd runs as SCHED_OTHER task which means it will compete with other tasks for CPU resources. This can introduce long delays for timer processing on heavy loaded systems and is not desired. Split the TIMER_SOFTIRQ and HRTIMER_SOFTIRQ processing into a dedicated timers thread and let it run at the lowest SCHED_FIFO priority. Wake-ups for RT tasks happen from hardirq context so only timer_list timers and hrtimers for "regular" tasks are processed here. The higher priority ensures that wakeups are performed before scheduling SCHED_OTHER tasks. Using a dedicated variable to store the pending softirq bits values ensure that the timer are not accidentally picked up by ksoftirqd and other threaded interrupts. It shouldn't be picked up by ksoftirqd since it runs at lower priority. However if ksoftirqd is already running while a timer fires, then ksoftird will be PI-boosted due to the BH-lock to ktimer's priority. The timer thread can pick up pending softirqs from ksoftirqd but only if the softirq load is high. It is not be desired that the picked up softirqs are processed at SCHED_FIFO priority under high softirq load but this can already happen by a PI-boost by a force-threaded interrupt. [ frederic@kernel.org: rcutorture.c fixes, storm fix by introduction of local_timers_pending() for tick_nohz_next_event() ] [ junxiao.chang@intel.com: Ensure ktimersd gets woken up even if a softirq is currently served. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> [rcutorture] Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/all/20241106150419.2593080-4-bigeasy@linutronix.de
2024-09-09Merge branches 'context_tracking.15.08.24a', 'csd.lock.15.08.24a', ↵Neeraj Upadhyay
'nocb.09.09.24a', 'rcutorture.14.08.24a', 'rcustall.09.09.24a', 'srcu.12.08.24a', 'rcu.tasks.14.08.24a', 'rcu_scaling_tests.15.08.24a', 'fixes.12.08.24a' and 'misc.11.08.24a' into next.09.09.24a
2024-08-15rcu: Rename rcu_momentary_dyntick_idle() into rcu_momentary_eqs()Valentin Schneider
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to RCU_WATCHING, replace "dyntick_idle" into "eqs" to drop the dyntick reference. Signed-off-by: Valentin Schneider <vschneid@redhat.com> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
2024-08-14rcutorture: Stop testing RCU Tasks Rude asynchronous APIsPaul E. McKenney
The call_rcu_tasks_rude() and rcu_barrier_tasks_rude() APIs are currently unused. Furthermore, the idea is to get rid of RCU Tasks Rude entirely once all architectures have their deep-idle and entry/exit code correctly marked as inline or noinstr. As a first step towards this goal, this commit therefore removes these two functions from rcutorture testing. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
2024-08-14rcutorture: Add a stall_cpu_repeat module parameterPaul E. McKenney
This commit adds an stall_cpu_repeat kernel, which is also the rcutorture.stall_cpu_repeat boot parameter, to test repeated CPU stalls. Note that only the first stall will pay attention to the stall_cpu_irqsoff module parameter. For the second and subsequent stalls, interrupts will be enabled. This is helpful when testing the interaction between RCU CPU stall warnings and CSD-lock stall warnings. Reported-by: Rik van Riel <riel@surriel.com> Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
2024-07-29rcutorture: Make rcu_torture_write_types() print number of update typesPaul E. McKenney
This commit follows the list of update types with their count, resulting in console output like this: rcu_torture_write_types: Testing conditional GPs. rcu_torture_write_types: Testing conditional expedited GPs. rcu_torture_write_types: Testing conditional full-state GPs. rcu_torture_write_types: Testing expedited GPs. rcu_torture_write_types: Testing asynchronous GPs. rcu_torture_write_types: Testing polling GPs. rcu_torture_write_types: Testing polling full-state GPs. rcu_torture_write_types: Testing polling expedited GPs. rcu_torture_write_types: Testing polling full-state expedited GPs. rcu_torture_write_types: Testing normal GPs. rcu_torture_write_types: Testing 10 update types This commit adds the final line giving the count. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
2024-07-29rcutorture: Generic test for NUM_ACTIVE_*RCU_POLL*Paul E. McKenney
The rcutorture test suite has specific tests for both of the NUM_ACTIVE_RCU_POLL_OLDSTATE and NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE macros provided for RCU polled grace periods. However, with the advent of NUM_ACTIVE_SRCU_POLL_OLDSTATE, a more generic test is needed. This commit therefore adds ->poll_active and ->poll_active_full fields to the rcu_torture_ops structure and converts the existing specific tests to use these fields, when present. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
2024-07-29rcutorture: Add SRCU ->same_gp_state and ->get_comp_state functionsPaul E. McKenney
This commit points the SRCU ->same_gp_state and ->get_comp_state fields to same_state_synchronize_srcu() and get_completed_synchronize_srcu(), allowing them to be tested. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
2024-07-29rcutorture: Remove redundant rcu_torture_ops get_gp_completed fieldsPaul E. McKenney
The rcu_torture_ops structure's ->get_gp_completed and ->get_gp_completed_full fields are redundant with its ->get_comp_state and ->get_comp_state_full fields. This commit therefore removes the former in favor of the latter. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
2024-06-06rcutorture: Add missing MODULE_DESCRIPTION() macrosJeff Johnson
Fix the following 'make W=1' warnings: WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/rcutorture.o WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/rcuscale.o WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/refscale.o Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2024-06-06rcutorture: Fix rcu_torture_fwd_cb_cr() data racePaul E. McKenney
On powerpc systems, spinlock acquisition does not order prior stores against later loads. This means that this statement: rfcp->rfc_next = NULL; Can be reordered to follow this statement: WRITE_ONCE(*rfcpp, rfcp); Which is then a data race with rcu_torture_fwd_prog_cr(), specifically, this statement: rfcpn = READ_ONCE(rfcp->rfc_next) KCSAN located this data race, which represents a real failure on powerpc. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Acked-by: Marco Elver <elver@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: <kasan-dev@googlegroups.com>
2024-06-03rcutorture: Make rcutorture support srcu double call testZqiang
This commit allows rcutorture to test double-call_srcu() when the CONFIG_DEBUG_OBJECTS_RCU_HEAD Kconfig option is enabled. The non-raw sdp structure's ->spinlock will be acquired in call_srcu(), hence this commit also removes the current IRQ and preemption disabling so as to avoid lockdep complaints. Link: https://lore.kernel.org/all/20240407112714.24460-1-qiang.zhang1211@gmail.com/ Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2024-04-16rcutorture: Use rcu_gp_slow_register/unregister() only for rcutype testZqiang
The rcu_gp_slow_register/unregister() is only useful in tests where torture_type=rcu, so this commit therefore generates ->gp_slow_register() and ->gp_slow_unregister() function pointers in the rcu_torture_ops structure, and slows grace periods only when these function pointers exist. Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-16rcutorture: Fix invalid context warning when enable srcu barrier testingZqiang
When the torture_type is set srcu or srcud and cb_barrier is non-zero, running the rcutorture test will trigger the following warning: [ 163.910989][ C1] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 [ 163.910994][ C1] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1 [ 163.910999][ C1] preempt_count: 10001, expected: 0 [ 163.911002][ C1] RCU nest depth: 0, expected: 0 [ 163.911005][ C1] INFO: lockdep is turned off. [ 163.911007][ C1] irq event stamp: 30964 [ 163.911010][ C1] hardirqs last enabled at (30963): [<ffffffffabc7df52>] do_idle+0x362/0x500 [ 163.911018][ C1] hardirqs last disabled at (30964): [<ffffffffae616eff>] sysvec_call_function_single+0xf/0xd0 [ 163.911025][ C1] softirqs last enabled at (0): [<ffffffffabb6475f>] copy_process+0x16ff/0x6580 [ 163.911033][ C1] softirqs last disabled at (0): [<0000000000000000>] 0x0 [ 163.911038][ C1] Preemption disabled at: [ 163.911039][ C1] [<ffffffffacf1964b>] stack_depot_save_flags+0x24b/0x6c0 [ 163.911063][ C1] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G W 6.8.0-rc4-rt4-yocto-preempt-rt+ #3 1e39aa9a737dd024a3275c4f835a872f673a7d3a [ 163.911071][ C1] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 [ 163.911075][ C1] Call Trace: [ 163.911078][ C1] <IRQ> [ 163.911080][ C1] dump_stack_lvl+0x88/0xd0 [ 163.911089][ C1] dump_stack+0x10/0x20 [ 163.911095][ C1] __might_resched+0x36f/0x530 [ 163.911105][ C1] rt_spin_lock+0x82/0x1c0 [ 163.911112][ C1] spin_lock_irqsave_ssp_contention+0xb8/0x100 [ 163.911121][ C1] srcu_gp_start_if_needed+0x782/0xf00 [ 163.911128][ C1] ? _raw_spin_unlock_irqrestore+0x46/0x70 [ 163.911136][ C1] ? debug_object_active_state+0x336/0x470 [ 163.911148][ C1] ? __pfx_srcu_gp_start_if_needed+0x10/0x10 [ 163.911156][ C1] ? __pfx_lock_release+0x10/0x10 [ 163.911165][ C1] ? __pfx_rcu_torture_barrier_cbf+0x10/0x10 [ 163.911188][ C1] __call_srcu+0x9f/0xe0 [ 163.911196][ C1] call_srcu+0x13/0x20 [ 163.911201][ C1] srcu_torture_call+0x1b/0x30 [ 163.911224][ C1] rcu_torture_barrier1cb+0x4a/0x60 [ 163.911247][ C1] __flush_smp_call_function_queue+0x267/0xca0 [ 163.911256][ C1] ? __pfx_rcu_torture_barrier1cb+0x10/0x10 [ 163.911281][ C1] generic_smp_call_function_single_interrupt+0x13/0x20 [ 163.911288][ C1] __sysvec_call_function_single+0x7d/0x280 [ 163.911295][ C1] sysvec_call_function_single+0x93/0xd0 [ 163.911302][ C1] </IRQ> [ 163.911304][ C1] <TASK> [ 163.911308][ C1] asm_sysvec_call_function_single+0x1b/0x20 [ 163.911313][ C1] RIP: 0010:default_idle+0x17/0x20 [ 163.911326][ C1] RSP: 0018:ffff888001997dc8 EFLAGS: 00000246 [ 163.911333][ C1] RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffffffae618b51 [ 163.911337][ C1] RDX: 0000000000000000 RSI: ffffffffaea80920 RDI: ffffffffaec2de80 [ 163.911342][ C1] RBP: ffff888001997dc8 R08: 0000000000000001 R09: ffffed100d740cad [ 163.911346][ C1] R10: ffffed100d740cac R11: ffff88806ba06563 R12: 0000000000000001 [ 163.911350][ C1] R13: ffffffffafe460c0 R14: ffffffffafe460c0 R15: 0000000000000000 [ 163.911358][ C1] ? ct_kernel_exit.constprop.3+0x121/0x160 [ 163.911369][ C1] ? lockdep_hardirqs_on+0xc4/0x150 [ 163.911376][ C1] arch_cpu_idle+0x9/0x10 [ 163.911383][ C1] default_idle_call+0x7a/0xb0 [ 163.911390][ C1] do_idle+0x362/0x500 [ 163.911398][ C1] ? __pfx_do_idle+0x10/0x10 [ 163.911404][ C1] ? complete_with_flags+0x8b/0xb0 [ 163.911416][ C1] cpu_startup_entry+0x58/0x70 [ 163.911423][ C1] start_secondary+0x221/0x280 [ 163.911430][ C1] ? __pfx_start_secondary+0x10/0x10 [ 163.911440][ C1] secondary_startup_64_no_verify+0x17f/0x18b [ 163.911455][ C1] </TASK> This commit therefore use smp_call_on_cpu() instead of smp_call_function_single(), make rcu_torture_barrier1cb() invoked happens on task-context. Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-16rcutorture: Make stall-tasks directly exit when rcutorture tests endZqiang
When the rcutorture tests start to exit, the rcu_torture_cleanup() is invoked to stop kthreads and release resources, if the stall-task kthreads exist, cpu-stall has started and the rcutorture.stall_cpu is set to a larger value, the rcu_torture_cleanup() will be blocked for a long time and the hung-task may occur, this commit therefore add kthread_should_stop() to the loop of cpu-stall operation, when rcutorture tests ends, no need to wait for cpu-stall to end, exit directly. Use the following command to test: insmod rcutorture.ko torture_type=srcu fwd_progress=0 stat_interval=4 stall_cpu_block=1 stall_cpu=200 stall_cpu_holdoff=10 read_exit_burst=0 object_debug=1 rmmod rcutorture [15361.918610] INFO: task rmmod:878 blocked for more than 122 seconds. [15361.918613] Tainted: G W 6.8.0-rc2-yoctodev-standard+ #25 [15361.918615] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [15361.918616] task:rmmod state:D stack:0 pid:878 tgid:878 ppid:773 flags:0x00004002 [15361.918621] Call Trace: [15361.918623] <TASK> [15361.918626] __schedule+0xc0d/0x28f0 [15361.918631] ? __pfx___schedule+0x10/0x10 [15361.918635] ? rcu_is_watching+0x19/0xb0 [15361.918638] ? schedule+0x1f6/0x290 [15361.918642] ? __pfx_lock_release+0x10/0x10 [15361.918645] ? schedule+0xc9/0x290 [15361.918648] ? schedule+0xc9/0x290 [15361.918653] ? trace_preempt_off+0x54/0x100 [15361.918657] ? schedule+0xc9/0x290 [15361.918661] schedule+0xd0/0x290 [15361.918665] schedule_timeout+0x56d/0x7d0 [15361.918669] ? debug_smp_processor_id+0x1b/0x30 [15361.918672] ? rcu_is_watching+0x19/0xb0 [15361.918676] ? __pfx_schedule_timeout+0x10/0x10 [15361.918679] ? debug_smp_processor_id+0x1b/0x30 [15361.918683] ? rcu_is_watching+0x19/0xb0 [15361.918686] ? wait_for_completion+0x179/0x4c0 [15361.918690] ? __pfx_lock_release+0x10/0x10 [15361.918693] ? __kasan_check_write+0x18/0x20 [15361.918696] ? wait_for_completion+0x9d/0x4c0 [15361.918700] ? _raw_spin_unlock_irq+0x36/0x50 [15361.918703] ? wait_for_completion+0x179/0x4c0 [15361.918707] ? _raw_spin_unlock_irq+0x36/0x50 [15361.918710] ? wait_for_completion+0x179/0x4c0 [15361.918714] ? trace_preempt_on+0x54/0x100 [15361.918718] ? wait_for_completion+0x179/0x4c0 [15361.918723] wait_for_completion+0x181/0x4c0 [15361.918728] ? __pfx_wait_for_completion+0x10/0x10 [15361.918738] kthread_stop+0x152/0x470 [15361.918742] _torture_stop_kthread+0x44/0xc0 [torture 7af7f9cbba28271a10503b653f9e05d518fbc8c3] [15361.918752] rcu_torture_cleanup+0x2ac/0xe90 [rcutorture f2cb1f556ee7956270927183c4c2c7749a336529] [15361.918766] ? __pfx_rcu_torture_cleanup+0x10/0x10 [rcutorture f2cb1f556ee7956270927183c4c2c7749a336529] [15361.918777] ? __kasan_check_write+0x18/0x20 [15361.918781] ? __mutex_unlock_slowpath+0x17c/0x670 [15361.918789] ? __might_fault+0xcd/0x180 [15361.918793] ? find_module_all+0x104/0x1d0 [15361.918799] __x64_sys_delete_module+0x2a4/0x3f0 [15361.918803] ? __pfx___x64_sys_delete_module+0x10/0x10 [15361.918807] ? syscall_exit_to_user_mode+0x149/0x280 Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-16rcutorture: Removing redundant function pointer initializationZqiang
For these rcu_torture_ops structure's objects defined by using static, if the value of the function pointer in its member is not set, the default value will be NULL, this commit therefore remove the pre-existing initialization of function pointers to NULL. Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-16rcutorture: Make rcutorture support print rcu-tasks gp stateZqiang
This commit make rcu-tasks related rcutorture test support rcu-tasks gp state printing when the writer stall occurs or the at the end of rcutorture test, and generate rcu_ops->get_gp_data() operation to simplify the acquisition of gp state for different types of rcutorture tests. Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-16rcutorture: Use the gp_kthread_dbg operation specified by cur_opsZqiang
Despite there being a cur_ops->gp_kthread_dbg(), rcu_torture_writer() unconditionally invokes vanilla RCU's show_rcu_gp_kthreads(). This is not at all helpful when some other flavor of RCU is being tested. This commit therefore makes rcu_torture_writer() invoke cur_ops->gp_kthread_dbg() for RCU implementations providing this function. Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-16rcutorture: Re-use value stored to ->rtort_pipe_count instead of re-readinglinke li
Currently, the rcu_torture_pipe_update_one() writes the value (i + 1) to rp->rtort_pipe_count, then immediately re-reads it in order to compare it to RCU_TORTURE_PIPE_LEN. This re-read is pointless because no other update to rp->rtort_pipe_count can occur at this point. This commit therefore instead re-uses the (i + 1) value stored in the comparison instead of re-reading rp->rtort_pipe_count. Signed-off-by: linke li <lilinke99@qq.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-16rcutorture: Fix rcu_torture_one_read() pipe_count overflow commentPaul E. McKenney
The "pipe_count > RCU_TORTURE_PIPE_LEN" check has a comment saying "Should not happen, but...". This is only true when testing an RCU whose grace periods are always long enough. This commit therefore fixes this comment. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Closes: https://lore.kernel.org/lkml/CAHk-=wi7rJ-eGq+xaxVfzFEgbL9tdf6Kc8Z89rCpfcQOKm74Tw@mail.gmail.com/ Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-16rcutorture: Remove extraneous rcu_torture_pipe_update_one() READ_ONCE()Paul E. McKenney
The rcu_torture_pipe_update_one() cannot run concurrently with any updates of ->rtort_pipe_count, so this commit removes the extraneous READ_ONCE() from the read from this field. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Closes: https://lore.kernel.org/lkml/CAHk-=wiX_zF5Mpt8kUm_LFQpYY-mshrXJPOe+wKNwiVhEUcU9g@mail.gmail.com/ Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-09rcutorture: ASSERT_EXCLUSIVE_WRITER() for ->rtort_pipe_count updatesPaul E. McKenney
It turns out that only one CPU at a time will ever invoke rcu_torture_pipe_update_one() on a given rcu_torture structure. This commit therefore adds three ASSERT_EXCLUSIVE_WRITER() calls to enlist KCSAN's aid in checking this. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-09rcutorture: Dump GP kthread state on insufficient cb-flood launderingPaul E. McKenney
If a callback flood prevents grace period from completing, rcutorture does a WARN_ON(). Avoiding this WARN_ON() currently requires that at least three grace periods elapse during an eight-second callback-flood interval. Unfortunately, the current debug information does not include anything about the grace-period state. This commit therefore adds a call to cur_ops->gp_kthread_dbg(), if this function pointer is non-NULL. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-04-09rcutorture: Dump # online CPUs on insufficient cb-flood launderingPaul E. McKenney
This commit adds the number of online CPUs to the state dump following an unsuccesful callback-flood test. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
2024-02-14rcutorture: Suppress rtort_pipe_count warnings until after stallsPaul E. McKenney
Currently, if rcu_torture_writer() sees fewer than ten grace periods having elapsed during a call to stutter_wait() that actually waited, the rtort_pipe_count warning is emitted. This has worked well for a long time. Except that the rcutorture TREE07 scenario now does a short-term 14-second RCU CPU stall, which can most definitely case false-positive rtort_pipe_count warnings. This commit therefore changes rcu_torture_writer() to compute the full expected holdoff and stall duration, and to refuse to report any rtort_pipe_count warnings until after all stalls have completed. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2023-12-14Merge branches 'doc.2023.12.13a', 'torture.2023.11.23a', ↵Neeraj Upadhyay (AMD)
'fixes.2023.12.13a', 'rcu-tasks.2023.12.12b' and 'srcu.2023.12.13a' into rcu-merge.2023.12.13a
2023-12-12rcu: Restrict access to RCU CPU stall notifiersPaul E. McKenney
Although the RCU CPU stall notifiers can be useful for dumping state when tracking down delicate forward-progress bugs where NUMA effects cause cache lines to be delivered to a given CPU regularly, but always in a state that prevents that CPU from making forward progress. These bugs can be detected by the RCU CPU stall-warning mechanism, but in some cases, the stall-warnings printk()s disrupt the forward-progress bug before any useful state can be obtained. Unfortunately, the notifier mechanism added by commit 5b404fdabacf ("rcu: Add RCU CPU stall notifier") can make matters worse if used at all carelessly. For example, if the stall warning was caused by a lock not being released, then any attempt to acquire that lock in the notifier will hang. This will prevent not only the notifier from producing any useful output, but it will also prevent the stall-warning message from ever appearing. This commit therefore hides this new RCU CPU stall notifier mechanism under a new RCU_CPU_STALL_NOTIFIER Kconfig option that depends on both DEBUG_KERNEL and RCU_EXPERT. In addition, the rcupdate.rcu_cpu_stall_notifiers=1 kernel boot parameter must also be specified. The RCU_CPU_STALL_NOTIFIER Kconfig option's help text contains a warning and explains the dangers of careless use, recommending lockless notifier code. In addition, a WARN() is triggered each time that an attempt is made to register a stall-warning notifier in kernels built with CONFIG_RCU_CPU_STALL_NOTIFIER=y. This combination of measures will keep use of this mechanism confined to debug kernels and away from routine deployments. [ paulmck: Apply Dan Carpenter feedback. ] Fixes: 5b404fdabacf ("rcu: Add RCU CPU stall notifier") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.iitr10@gmail.com>
2023-11-23rcutorture: Add fqs_holdoff check before fqs_task is createdZqiang
For rcutorture tests on RCU implementations that support force-quiescent-state operations and that set the fqs_duration module parameter greater than zero, the fqs_task kthread will be created. However, if the fqs_holdoff module parameter is not set, then its default value of zero will cause fqs_task enter a long-term busy loop until stopped by kthread_stop(). This commit therefore adds a fqs_holdoff check before the fqs_task is created, making sure that whenever the fqs_task is created, the fqs_holdoff will be greater than zero. Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.iitr10@gmail.com>
2023-10-23Merge branches 'rcu/torture', 'rcu/fixes', 'rcu/docs', 'rcu/refscale', ↵Frederic Weisbecker
'rcu/tasks' and 'rcu/stall' into rcu/next rcu/torture: RCU torture, locktorture and generic torture infrastructure rcu/fixes: Generic and misc fixes rcu/docs: RCU documentation updates rcu/refscale: RCU reference scalability test updates rcu/tasks: RCU tasks updates rcu/stall: Stall detection updates
2023-09-24rcutorture: Traverse possible cpu to set maxcpu in rcu_nocb_toggle()Zqiang
Currently, the maxcpu is set by traversing online CPUs, however, if the rcutorture.onoff_holdoff is set zero and onoff_interval is set non-zero, and the some CPUs with larger cpuid has been offline before setting maxcpu, for these CPUs, even if they are online again, also cannot be offload or deoffload. This can result in rcutorture attempting to (de-)offload CPUs that have never been online, but the (de-)offload code handles this. This commit therefore use for_each_possible_cpu() instead of for_each_online_cpu() in rcu_nocb_toggle(). Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
2023-09-24rcutorture: Replace schedule_timeout*() 1-jiffy waits with HZ/20Joel Fernandes (Google)
In the past, spinning on schedule_timeout* with a wait of 1 jiffy has hung the kernel. See for example d52d3a2bf408 ("torture: Fix hang during kthread shutdown phase"). This issue recently recurred in torture's stutter code. The result is that the function instantly returns and never goes to sleep, preempting whatever might otherwise make useful forward progress. To prevent future issues, apply the commit-d52d3a2bf408 fix throughout rcutorture, moving from a 1-jiffy wait to a 50-millisecond wait. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
2023-09-24torture: Move rcutorture_sched_setaffinity() out of rcutorturePaul E. McKenney
The rcutorture_sched_setaffinity() function is needed by locktorture, so move its declaration from rcu.h to torture.h and rename it to the more generic torture_sched_setaffinity() name. Please note that use of this function is still restricted to torture tests, and of those, currently only rcutorture and locktorture. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
2023-09-11rcutorture: Add test of RCU CPU stall notifiersPaul E. McKenney
This commit registers an RCU CPU stall notifier when testing RCU CPU stalls. The notifier logs a message similar to the following: rcu_torture_stall_nf: v=1, duration=21001. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
2023-08-14rcutorture: Stop right-shifting torture_random() return valuesPaul E. McKenney
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 <paulmck@kernel.org>
2023-07-14rcutorture: Dump grace-period state upon rtort_pipe_count incidentsPaul E. McKenney
The rtort_pipe_count WARN() indicates that grace periods were unable to invoke all callbacks during a stutter_wait() interval. But it is sometimes helpful to have a bit more information as to why. This commit therefore invokes show_rcu_gp_kthreads() immediately before that WARN() in order to dump out some relevant information. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-04-05Merge branches 'rcu/staging-core', 'rcu/staging-docs' and ↵Joel Fernandes (Google)
'rcu/staging-kfree', remote-tracking branches 'paul/srcu-cf.2023.04.04a', 'fbq/rcu/lockdep.2023.03.27a' and 'fbq/rcu/rcutorture.2023.03.20a' into rcu/staging
2023-03-27rcutorture: Add RCU Tasks Trace and SRCU deadlock scenariosPaul E. McKenney
Add a test number 3 that creates deadlock cycles involving one RCU Tasks Trace step and L-1 SRCU steps. Please note that lockdep will not detect these deadlocks until synchronize_rcu_tasks_trace() is marked with lockdep's new "sync" annotation, which will probably not happen until some time after these markings prove their worth on SRCU. Please note that these tests are available only in kernels built with CONFIG_TASKS_TRACE_RCU=y. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2023-03-27rcutorture: Add SRCU deadlock scenariosPaul E. McKenney
In order to test the new SRCU-lockdep functionality, this commit adds an rcutorture.test_srcu_lockdep module parameter that, when non-zero, selects an SRCU deadlock scenario to execute. This parameter is a five-digit number formatted as DNNL, where "D" is 1 to force a deadlock and 0 to avoid doing so; "NN" is the test number, 0 for SRCU-based, 1 for SRCU/mutex-based, and 2 for SRCU/rwsem-based; and "L" is the number of steps in the deadlock cycle. Note that rcutorture.test_srcu_lockdep=1 will also force a hard hang. If a non-zero value of rcutorture.test_srcu_lockdep does not select a deadlock scenario, a console message is printed and testing continues. [ paulmck: Apply kernel test robot feedback, add rwsem support. ] [ paulmck: Apply Dan Carpenter feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2023-03-20rcutorture: Create nocb kthreads only when testing rcu in ↵Zqiang
CONFIG_RCU_NOCB_CPU=y kernels Given a non-zero rcutorture.nocbs_nthreads module parameter, the specified number of nocb kthreads will be created, regardless of whether or not the RCU implementation under test is capable of offloading callbacks. Please note that even vanilla RCU is incapable of offloading in kernels built with CONFIG_RCU_NOCB_CPU=n. And when the RCU implementation is incapable of offloading callbacks, there is no point in creating those kthreads. This commit therefore checks the cur_ops.torture_type module parameter and CONFIG_RCU_NOCB_CPU Kconfig option in order to avoid creating unnecessary nocb tasks. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> [ boqun: Fix checkpatch warning ] Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2023-03-11rcutorture: Eliminate variable n_rcu_torture_boost_rterrorYue Hu
After commit 8b700983de82 ("sched: Remove sched_set_*() return value"), this variable is not used anymore. So eliminate it entirely. Signed-off-by: Yue Hu <huyue2@coolpad.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2023-03-11rcutorture: Add test_nmis module parameterPaul E. McKenney
This commit adds a test_nmis module parameter to generate the specified number of NMI stack backtraces 15 seconds apart. This module parameter can be used to test NMI delivery and accompanying diagnostics. Note that this parameter is ignored when rcutorture is a module rather than built into the kernel. This could be changed with the addition of an EXPORT_SYMBOL_GPL(). [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2023-01-05rcutorture: Drop sparse lock-acquisition annotationsPaul E. McKenney
The sparse __acquires() and __releases() annotations provide very little value. The argument is ignored, so sparse cannot tell the differences between acquiring one lock and releasing another on the one hand and acquiring and releasing a given lock on the other. In addition, lockdep annotations provide much more precision, for but one example, actually knowing which lock is held. This commit therefore removes the __acquires() and __releases() annotations from rcutorture. Reported-by: Tejun Heo <tj@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-11-30Merge branches 'doc.2022.10.20a', 'fixes.2022.10.21a', 'lazy.2022.11.30a', ↵Paul E. McKenney
'srcunmisafe.2022.11.09a', 'torture.2022.10.18c' and 'torturescript.2022.10.20a' into HEAD doc.2022.10.20a: Documentation updates. fixes.2022.10.21a: Miscellaneous fixes. lazy.2022.11.30a: Lazy call_rcu() and NOCB updates. srcunmisafe.2022.11.09a: NMI-safe SRCU readers. torture.2022.10.18c: Torture-test updates. torturescript.2022.10.20a: Torture-test scripting updates.
2022-11-29rcu/rcutorture: Use call_rcu_hurry() where neededJoel Fernandes (Google)
call_rcu() changes to save power will change the behavior of rcutorture tests. Use the call_rcu_hurry() API instead which reverts to the old behavior. [ paulmck: Apply s/call_rcu_flush/call_rcu_hurry/ feedback from Tejun Heo. ] Reported-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-10-20srcu: Create an srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe()Paul E. McKenney
On strict load-store architectures, the use of this_cpu_inc() by srcu_read_lock() and srcu_read_unlock() is not NMI-safe in TREE SRCU. To see this suppose that an NMI arrives in the middle of srcu_read_lock(), just after it has read ->srcu_lock_count, but before it has written the incremented value back to memory. If that NMI handler also does srcu_read_lock() and srcu_read_lock() on that same srcu_struct structure, then upon return from that NMI handler, the interrupted srcu_read_lock() will overwrite the NMI handler's update to ->srcu_lock_count, but leave unchanged the NMI handler's update by srcu_read_unlock() to ->srcu_unlock_count. This can result in a too-short SRCU grace period, which can in turn result in arbitrary memory corruption. If the NMI handler instead interrupts the srcu_read_unlock(), this can result in eternal SRCU grace periods, which is not much better. This commit therefore creates a pair of new srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe() functions, which allow SRCU readers in both NMI handlers and in process and IRQ context. It is bad practice to mix the existing and the new _nmisafe() primitives on the same srcu_struct structure. Use one set or the other, not both. Just to underline that "bad practice" point, using srcu_read_lock() at process level and srcu_read_lock_nmisafe() in your NMI handler will not, repeat NOT, work. If you do not immediately understand why this is the case, please review the earlier paragraphs in this commit log. [ paulmck: Apply kernel test robot feedback. ] [ paulmck: Apply feedback from Randy Dunlap. ] [ paulmck: Apply feedback from John Ogness. ] [ paulmck: Apply feedback from Frederic Weisbecker. ] Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/ Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: John Ogness <john.ogness@linutronix.de> Cc: Petr Mladek <pmladek@suse.com>
2022-10-18rcutorture: Verify NUM_ACTIVE_RCU_POLL_OLDSTATEPaul E. McKenney
This commit adds code to the RTWS_POLL_GET case of rcu_torture_writer() to verify that the value of NUM_ACTIVE_RCU_POLL_OLDSTATE is sufficiently large Signed-off-by: Paul E. McKenney <paulmck@kernel.org>