Hosts the 0x221E linux distro kernel. https://git.0xinfinity.dev/distro/kernel.git/atom?h=linux-5.14.y 2021-09-15T08:02:07Z 2021-09-15T08:02:07Z Yanfei Xu 2021-05-16T09:50:10Z urn:sha1:8af14fb35efc7279d390fc7e7c6054b59c65b167 [ Upstream commit dc87740c8a6806bd2162bfb441770e4e53be5601 ] If rcu_print_task_stall() is invoked on an rcu_node structure that does not contain any tasks blocking the current grace period, it takes an early exit that fails to release that rcu_node structure's lock. This results in a self-deadlock, which is detected by lockdep. To reproduce this bug: tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --duration 3 --trust-make --configs "TREE03" --kconfig "CONFIG_PROVE_LOCKING=y" --bootargs "rcutorture.stall_cpu=30 rcutorture.stall_cpu_block=1 rcutorture.fwd_progress=0 rcutorture.test_boost=0" This will also result in other complaints, including RCU's scheduler hook complaining about blocking rather than preemption and an rcutorture writer stall. Only a partial RCU CPU stall warning message will be printed because of the self-deadlock. This commit therefore releases the lock on the rcu_print_task_stall() function's early exit path. Fixes: c583bcb8f5ed ("rcu: Don't invoke try_invoke_on_locked_down_task() with irqs disabled") Tested-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 2021-09-15T08:02:07Z Yanfei Xu 2021-05-15T16:45:11Z urn:sha1:0133d52e0eb243c98880a4dcb0d00d350eeb6449 [ Upstream commit e6a901a44f76878ed1653626c9ff4cfc5a3f58f8 ] The for loop in rcu_print_task_stall() always omits ts[0], which points to the first task blocking the stalled grace period. This in turn fails to count this first task, which means that ndetected will be equal to zero when all CPUs have passed through their quiescent states and only one task is blocking the stalled grace period. This zero value for ndetected will in turn result in an incorrect "All QSes seen" message: rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-1 rcu_node (CPUs 12-23): (detected by 15, t=6504 jiffies, g=164777, q=9011209) rcu: All QSes seen, last rcu_preempt kthread activity 1 (4295252379-4295252378), jiffies_till_next_fqs=1, root ->qsmask 0x2 BUG: sleeping function called from invalid context at include/linux/uaccess.h:156 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 70613, name: msgstress04 INFO: lockdep is turned off. Preemption disabled at: [<ffff8000104031a4>] create_object.isra.0+0x204/0x4b0 CPU: 15 PID: 70613 Comm: msgstress04 Kdump: loaded Not tainted 5.12.2-yoctodev-standard #1 Hardware name: Marvell OcteonTX CN96XX board (DT) Call trace: dump_backtrace+0x0/0x2cc show_stack+0x24/0x30 dump_stack+0x110/0x188 ___might_sleep+0x214/0x2d0 __might_sleep+0x7c/0xe0 This commit therefore fixes the loop to include ts[0]. Fixes: c583bcb8f5ed ("rcu: Don't invoke try_invoke_on_locked_down_task() with irqs disabled") Tested-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 2021-09-15T08:02:02Z Sergey Senozhatsky 2021-05-21T15:56:23Z urn:sha1:f08a6566aaa460721fc1156ec24386a851a8d566 [ Upstream commit ccfc9dd6914feaa9a81f10f9cce56eb0f7712264 ] The soft watchdog timer function checks if a virtual machine was suspended and hence what looks like a lockup in fact is a false positive. This is what kvm_check_and_clear_guest_paused() does: it tests guest PVCLOCK_GUEST_STOPPED (which is set by the host) and if it's set then we need to touch all watchdogs and bail out. Watchdog timer function runs from IRQ, so PVCLOCK_GUEST_STOPPED check works fine. There is, however, one more watchdog that runs from IRQ, so watchdog timer fn races with it, and that watchdog is not aware of PVCLOCK_GUEST_STOPPED - RCU stall detector. apic_timer_interrupt() smp_apic_timer_interrupt() hrtimer_interrupt() __hrtimer_run_queues() tick_sched_timer() tick_sched_handle() update_process_times() rcu_sched_clock_irq() This triggers RCU stalls on our devices during VM resume. If tick_sched_handle()->rcu_sched_clock_irq() runs on a VCPU before watchdog_timer_fn()->kvm_check_and_clear_guest_paused() then there is nothing on this VCPU that touches watchdogs and RCU reads stale gp stall timestamp and new jiffies value, which makes it think that RCU has stalled. Make RCU stall watchdog aware of PVCLOCK_GUEST_STOPPED and don't report RCU stalls when we resume the VM. Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by: Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 2021-07-06T22:53:12Z Paul E. McKenney 2021-07-04T20:59:35Z urn:sha1:2a2ed5618a0e8a890d948b88b368c0459f35136c This commit changes from "%lx" to "%x" and from "0x1ffffL" to "0x1ffff" to match the change in type between the old field ->state (unsigned long) and the new field ->__state (unsigned int). Signed-off-by: Paul E. McKenney <paulmck@kernel.org> 2021-07-04T19:58:33Z Linus Torvalds 2021-07-04T19:58:33Z urn:sha1:28e92f990337b8b4c5fdec47667f8b96089c503e 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 ... 2021-06-18T09:43:09Z Peter Zijlstra 2021-06-11T08:28:17Z urn:sha1:2f064a59a11ff9bc22e52e9678bc601404c7cb34 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 2021-05-18T17:56:19Z Paul E. McKenney 2021-05-18T17:56:19Z urn:sha1:641faf1b9064c270a476a424e60063bb05df3ee9 bitmaprange.2021.05.10c: Allow "all" for bitmap ranges. doc.2021.05.10c: Documentation updates. fixes.2021.05.13a: Miscellaneous fixes. kvfree_rcu.2021.05.10c: kvfree_rcu() updates. mmdumpobj.2021.05.10c: mem_dump_obj() updates. nocb.2021.05.12a: RCU NOCB CPU updates, including limited deoffloading. srcu.2021.05.12a: SRCU updates. tasks.2021.05.18a: Tasks-RCU updates. torture.2021.05.10c: Torture-test updates. 2021-05-13T16:13:23Z Jules Irenge 2021-04-28T23:12:19Z urn:sha1:c70360c3343f975bd066b6b98159d93f1bd4219f Sparse reports a warning at rcu_print_task_stall(): "warning: context imbalance in rcu_print_task_stall - unexpected unlock" The root cause is a missing annotation on rcu_print_task_stall(). This commit therefore adds the missing __releases(rnp->lock) annotation. Signed-off-by: Jules Irenge <jbi.octave@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> 2021-05-10T23:44:11Z Paul E. McKenney 2021-04-15T23:30:34Z urn:sha1:5390473ec1697b71af0e9d63ef7aaa7ecd27e2c9 RCU priority boosting cannot do anything unless there is at least one task blocking the current RCU grace period that was preempted within the RCU read-side critical section that it still resides in. However, the current rcu_torture_boost_failed() code will count this as an RCU priority-boosting failure if there were no CPUs blocking the current grace period. This situation can happen (for example) if the last CPU blocking the current grace period was subjected to vCPU preemption, which is always a risk for rcutorture guest OSes. This commit therefore causes rcu_torture_boost_failed() to refrain from reporting failure unless there is at least one task blocking the current RCU grace period that was preempted within the RCU read-side critical section that it still resides in. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> 2021-05-10T23:22:54Z Paul E. McKenney 2021-04-07T22:14:01Z urn:sha1:b15805013b441b13fcf6e402c03421c03edb79c6 Currently, show_rcu_gp_kthreads() only dumps rcu_node structures that have outdated ideas of the current grace-period number. This commit also dumps those that are in any way blocking the current grace period. This helps diagnose RCU priority boosting failures. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>