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2020-01-24Merge branches 'doc.2019.12.10a', 'exp.2019.12.09a', 'fixes.2020.01.24a', ↵Paul E. McKenney
'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
2020-01-24rcu: Move gp_state_names[] and gp_state_getname() to tree_stall.hLai Jiangshan
Only tree_stall.h needs to get name from GP state, so this commit moves the gp_state_names[] array and the gp_state_getname() from kernel/rcu/tree.h and kernel/rcu/tree.c, respectively, to kernel/rcu/tree_stall.h. While moving gp_state_names[], this commit uses the GCC syntax to ensure that the right string is associated with the right CPP macro. Signed-off-by: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-01-24rcu: Rename some instance of CONFIG_PREEMPTION to CONFIG_PREEMPT_RCULai Jiangshan
CONFIG_PREEMPTION and CONFIG_PREEMPT_RCU are always identical, but some code depends on CONFIG_PREEMPTION to access to rcu_preempt functionality. This patch changes CONFIG_PREEMPTION to CONFIG_PREEMPT_RCU in these cases. Signed-off-by: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-01-24rcu: Remove kfree_rcu() special casing and lazy-callback handlingJoel Fernandes (Google)
This commit removes kfree_rcu() special-casing and the lazy-callback handling from Tree RCU. It moves some of this special casing to Tiny RCU, the removal of which will be the subject of later commits. This results in a nice negative delta. Suggested-by: Paul E. McKenney <paulmck@linux.ibm.com> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Add slab.h #include, thanks to kbuild test robot <lkp@intel.com>. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-09-16Merge branch 'sched-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: - MAINTAINERS: Add Mark Rutland as perf submaintainer, Juri Lelli and Vincent Guittot as scheduler submaintainers. Add Dietmar Eggemann, Steven Rostedt, Ben Segall and Mel Gorman as scheduler reviewers. As perf and the scheduler is getting bigger and more complex, document the status quo of current responsibilities and interests, and spread the review pain^H^H^H^H fun via an increase in the Cc: linecount generated by scripts/get_maintainer.pl. :-) - Add another series of patches that brings the -rt (PREEMPT_RT) tree closer to mainline: split the monolithic CONFIG_PREEMPT dependencies into a new CONFIG_PREEMPTION category that will allow the eventual introduction of CONFIG_PREEMPT_RT. Still a few more hundred patches to go though. - Extend the CPU cgroup controller with uclamp.min and uclamp.max to allow the finer shaping of CPU bandwidth usage. - Micro-optimize energy-aware wake-ups from O(CPUS^2) to O(CPUS). - Improve the behavior of high CPU count, high thread count applications running under cpu.cfs_quota_us constraints. - Improve balancing with SCHED_IDLE (SCHED_BATCH) tasks present. - Improve CPU isolation housekeeping CPU allocation NUMA locality. - Fix deadline scheduler bandwidth calculations and logic when cpusets rebuilds the topology, or when it gets deadline-throttled while it's being offlined. - Convert the cpuset_mutex to percpu_rwsem, to allow it to be used from setscheduler() system calls without creating global serialization. Add new synchronization between cpuset topology-changing events and the deadline acceptance tests in setscheduler(), which were broken before. - Rework the active_mm state machine to be less confusing and more optimal. - Rework (simplify) the pick_next_task() slowpath. - Improve load-balancing on AMD EPYC systems. - ... and misc cleanups, smaller fixes and improvements - please see the Git log for more details. * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits) sched/psi: Correct overly pessimistic size calculation sched/fair: Speed-up energy-aware wake-ups sched/uclamp: Always use 'enum uclamp_id' for clamp_id values sched/uclamp: Update CPU's refcount on TG's clamp changes sched/uclamp: Use TG's clamps to restrict TASK's clamps sched/uclamp: Propagate system defaults to the root group sched/uclamp: Propagate parent clamps sched/uclamp: Extend CPU's cgroup controller sched/topology: Improve load balancing on AMD EPYC systems arch, ia64: Make NUMA select SMP sched, perf: MAINTAINERS update, add submaintainers and reviewers sched/fair: Use rq_lock/unlock in online_fair_sched_group cpufreq: schedutil: fix equation in comment sched: Rework pick_next_task() slow-path sched: Allow put_prev_task() to drop rq->lock sched/fair: Expose newidle_balance() sched: Add task_struct pointer to sched_class::set_curr_task sched: Rework CPU hotplug task selection sched/{rt,deadline}: Fix set_next_task vs pick_next_task sched: Fix kerneldoc comment for ia64_set_curr_task ...
2019-08-13rcu/nocb: Print no-CBs diagnostics when rcutorture writer unduly delayedPaul E. McKenney
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>
2019-08-01rcu: Add kernel parameter to dump trace after RCU CPU stall warningPaul E. McKenney
This commit adds a rcu_cpu_stall_ftrace_dump kernel boot parameter, that, when set, causes the trace buffer to be dumped after an RCU CPU stall warning is printed. This kernel boot parameter is disabled by default, maintaining compatibility with previous behavior. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-07-31rcu: Use CONFIG_PREEMPTIONThomas Gleixner
CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same functionality which today depends on CONFIG_PREEMPT. Switch the conditionals in RCU to use CONFIG_PREEMPTION. That's the first step towards RCU on RT. The further tweaks are work in progress. This neither touches the selftest bits which need a closer look by Paul. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20190726212124.210156346@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-05-28rcu: Correctly unlock root node in rcu_check_gp_start_stall()Neeraj Upadhyay
On systems whose rcu_node tree has only one node, the rcu_check_gp_start_stall() function's values of rnp and rnp_root will be identical. In this case, it clearly does not make sense to release both rnp->lock and rnp_root->lock, but that is exactly what this function does in the last early exit. This commit therefore unlocks only rnp->lock when rnp and rnp_root are equal. Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org> Reviewed-by: Mukesh Ojha <mojha@codeaurora.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26rcu: Fix nohz status in stall warningNeeraj Upadhyay
The Documentation/RCU/stallwarn.txt file says that stall warnings print "D" if dyntick-idle processing is enabled, but the code in print_cpu_stall_fast_no_hz() prints "." instead. This commit therefore reverses the sense of the test to make the code match the documentation. Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26rcu: Move forward-progress checkers into tree_stall.hPaul E. McKenney
This commit further consolidates stall-warning functionality by moving forward-progress checkers into kernel/rcu/tree_stall.h, updating a comment or two while in the area. More specifically, this commit moves show_rcu_gp_kthreads(), rcu_check_gp_start_stall(), rcu_fwd_progress_check(), sysrq_rcu, sysrq_show_rcu(), sysrq_rcudump_op, and rcu_sysrq_init() from kernel/rcu/tree.c to kernel/rcu/tree_stall.h. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26rcu: Move irq-disabled stall-warning checking to tree_stall.hPaul E. McKenney
The rcu_iw_handler() function's sole purpose in life is to indicate whether a stalled CPU had interrupts disabled, so it belongs in kernel/rcu/tree_stall.h. This commit therefore makes that move, clarifying its header comment while in the area. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26rcu: Organize functions in tree_stall.hPaul E. McKenney
This commit does only code movement, removal of now-unneeded forward declarations, and addition of comments. It organizes the functions that implement RCU CPU stall warnings for normal grace periods into three categories: 1. Control of RCU CPU stall warnings, including computing timeouts. 2. Interaction of stall warnings with grace periods. 3. Actual printing of the RCU CPU stall-warning messages. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26rcu: Move FAST_NO_HZ stall-warning code to tree_stall.hPaul E. McKenney
This commit further consolidates the stall-warning code by moving print_cpu_stall_info() and its helper functions along with zero_cpu_stall_ticks() to kernel/rcu/tree_stall.h. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26rcu: Inline RCU stall-warning info helper functionsPaul E. McKenney
The print_cpu_stall_info_begin() and print_cpu_stall_info_end() print a single character each onto the console, and are a holdover from a time when RCU CPU stall warning messages could be abbreviated using a long-gone Kconfig option. This commit therefore adds these single characters to already-printed strings in the calling functions, and then eliminates both print_cpu_stall_info_begin() and print_cpu_stall_info_end(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26rcu: Inline RCU task stall-warning helper functionsPaul E. McKenney
The rcu_print_detail_task_stall(), rcu_print_task_stall_begin(), and rcu_print_task_stall_end() functions were defined to allow long-gone Kconfig options to provide an abbreviated RCU CPU stall warning printout. This commit saves a few lines of code by inlining them into their sole callers. While in the area, a useless call of rcu_print_detail_task_stall_rnp() on the root rcu_node structure was eliminated. If there is only one rcu_node structure, its tasks get printed twice, but if there are more, the root rcu_node structure is guaranteed to have an empty list of blocked tasks, hence the uselessness. (Long ago, root rcu_node structures with non-empty ->blkd_tasks lists could happen, but no longer.) Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26rcu: Move RCU CPU stall-warning code out of tree.cPaul E. McKenney
This commit completes the process of consolidating the code for RCU CPU stall warnings for normal grace periods by moving the remaining such code from kernel/rcu/tree.c to kernel/rcu/tree_stall.h. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26rcu: Move RCU CPU stall-warning code out of tree_plugin.hPaul E. McKenney
The RCU CPU stall-warning code for normal grace periods is currently scattered across two files, due to earlier Tiny RCU support for RCU CPU stall warnings and for old Kconfig options that have long since been retired. Given that it is hard for the lead RCU maintainer to find relevant stall-warning code, it would be good to consolidate it. This commit continues this process by moving stall-warning code from kernel/rcu/tree_plugin.c to a new kernel/rcu/tree_stall.h file. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26rcu: Move RCU CPU stall-warning code out of update.cPaul E. McKenney
The RCU CPU stall-warning code for normal grace periods is currently scattered across three files, due to earlier Tiny RCU support for RCU CPU stall warnings and for old Kconfig options that have long since been retired. Given that it is hard for the lead RCU maintainer to find relevant stall-warning code, it would be good to consolidate it. This commit starts this process by moving stall-warning code from kernel/rcu/update.c to a new kernel/rcu/tree_stall.h file. Note that the definitions of rcu_cpu_stall_suppress and rcu_cpu_stall_timeout must remain in kernel/rcu/update.h to provide compatibility for kernel boot parameter lists. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>