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* Merge tag 'mm-stable-2022-08-03' of ↵Linus Torvalds2022-08-051-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: "Most of the MM queue. A few things are still pending. Liam's maple tree rework didn't make it. This has resulted in a few other minor patch series being held over for next time. Multi-gen LRU still isn't merged as we were waiting for mapletree to stabilize. The current plan is to merge MGLRU into -mm soon and to later reintroduce mapletree, with a view to hopefully getting both into 6.1-rc1. Summary: - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe Lin, Yang Shi, Anshuman Khandual and Mike Rapoport - Some kmemleak fixes from Patrick Wang and Waiman Long - DAMON updates from SeongJae Park - memcg debug/visibility work from Roman Gushchin - vmalloc speedup from Uladzislau Rezki - more folio conversion work from Matthew Wilcox - enhancements for coherent device memory mapping from Alex Sierra - addition of shared pages tracking and CoW support for fsdax, from Shiyang Ruan - hugetlb optimizations from Mike Kravetz - Mel Gorman has contributed some pagealloc changes to improve latency and realtime behaviour. - mprotect soft-dirty checking has been improved by Peter Xu - Many other singleton patches all over the place" [ XFS merge from hell as per Darrick Wong in https://lore.kernel.org/all/YshKnxb4VwXycPO8@magnolia/ ] * tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (282 commits) tools/testing/selftests/vm/hmm-tests.c: fix build mm: Kconfig: fix typo mm: memory-failure: convert to pr_fmt() mm: use is_zone_movable_page() helper hugetlbfs: fix inaccurate comment in hugetlbfs_statfs() hugetlbfs: cleanup some comments in inode.c hugetlbfs: remove unneeded header file hugetlbfs: remove unneeded hugetlbfs_ops forward declaration hugetlbfs: use helper macro SZ_1{K,M} mm: cleanup is_highmem() mm/hmm: add a test for cross device private faults selftests: add soft-dirty into run_vmtests.sh selftests: soft-dirty: add test for mprotect mm/mprotect: fix soft-dirty check in can_change_pte_writable() mm: memcontrol: fix potential oom_lock recursion deadlock mm/gup.c: fix formatting in check_and_migrate_movable_page() xfs: fail dax mount if reflink is enabled on a partition mm/memcontrol.c: remove the redundant updating of stats_flush_threshold userfaultfd: don't fail on unrecognized features hugetlb_cgroup: fix wrong hugetlb cgroup numa stat ...
| * mm: shrinkers: provide shrinkers with namesRoman Gushchin2022-07-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently shrinkers are anonymous objects. For debugging purposes they can be identified by count/scan function names, but it's not always useful: e.g. for superblock's shrinkers it's nice to have at least an idea of to which superblock the shrinker belongs. This commit adds names to shrinkers. register_shrinker() and prealloc_shrinker() functions are extended to take a format and arguments to master a name. In some cases it's not possible to determine a good name at the time when a shrinker is allocated. For such cases shrinker_debugfs_rename() is provided. The expected format is: <subsystem>-<shrinker_type>[:<instance>]-<id> For some shrinkers an instance can be encoded as (MAJOR:MINOR) pair. After this change the shrinker debugfs directory looks like: $ cd /sys/kernel/debug/shrinker/ $ ls dquota-cache-16 sb-devpts-28 sb-proc-47 sb-tmpfs-42 mm-shadow-18 sb-devtmpfs-5 sb-proc-48 sb-tmpfs-43 mm-zspool:zram0-34 sb-hugetlbfs-17 sb-pstore-31 sb-tmpfs-44 rcu-kfree-0 sb-hugetlbfs-33 sb-rootfs-2 sb-tmpfs-49 sb-aio-20 sb-iomem-12 sb-securityfs-6 sb-tracefs-13 sb-anon_inodefs-15 sb-mqueue-21 sb-selinuxfs-22 sb-xfs:vda1-36 sb-bdev-3 sb-nsfs-4 sb-sockfs-8 sb-zsmalloc-19 sb-bpf-32 sb-pipefs-14 sb-sysfs-26 thp-deferred_split-10 sb-btrfs:vda2-24 sb-proc-25 sb-tmpfs-1 thp-zero-9 sb-cgroup2-30 sb-proc-39 sb-tmpfs-27 xfs-buf:vda1-37 sb-configfs-23 sb-proc-41 sb-tmpfs-29 xfs-inodegc:vda1-38 sb-dax-11 sb-proc-45 sb-tmpfs-35 sb-debugfs-7 sb-proc-46 sb-tmpfs-40 [roman.gushchin@linux.dev: fix build warnings] Link: https://lkml.kernel.org/r/Yr+ZTnLb9lJk6fJO@castle Reported-by: kernel test robot <lkp@intel.com> Link: https://lkml.kernel.org/r/20220601032227.4076670-4-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Cc: Dave Chinner <dchinner@redhat.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Kent Overstreet <kent.overstreet@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* | Merge tag 'char-misc-6.0-rc1' of ↵Linus Torvalds2022-08-041-2/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc Pull char / misc driver updates from Greg KH: "Here is the large set of char and misc and other driver subsystem changes for 6.0-rc1. Highlights include: - large set of IIO driver updates, additions, and cleanups - new habanalabs device support added (loads of register maps much like GPUs have) - soundwire driver updates - phy driver updates - slimbus driver updates - tiny virt driver fixes and updates - misc driver fixes and updates - interconnect driver updates - hwtracing driver updates - fpga driver updates - extcon driver updates - firmware driver updates - counter driver update - mhi driver fixes and updates - binder driver fixes and updates - speakup driver fixes All of these have been in linux-next for a while without any reported problems" * tag 'char-misc-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (634 commits) drivers: lkdtm: fix clang -Wformat warning char: remove VR41XX related char driver misc: Mark MICROCODE_MINOR unused spmi: trace: fix stack-out-of-bound access in SPMI tracing functions dt-bindings: iio: adc: Add compatible for MT8188 iio: light: isl29028: Fix the warning in isl29028_remove() iio: accel: sca3300: Extend the trigger buffer from 16 to 32 bytes iio: fix iio_format_avail_range() printing for none IIO_VAL_INT iio: adc: max1027: unlock on error path in max1027_read_single_value() iio: proximity: sx9324: add empty line in front of bullet list iio: magnetometer: hmc5843: Remove duplicate 'the' iio: magn: yas530: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: magnetometer: ak8974: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: veml6030: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: vcnl4035: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: vcnl4000: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: tsl2591: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() iio: light: tsl2583: Use DEFINE_RUNTIME_DEV_PM_OPS and pm_ptr() iio: light: isl29028: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() iio: light: gp2ap002: Switch to DEFINE_RUNTIME_DEV_PM_OPS and pm_ptr() ...
| * | remove CONFIG_ANDROIDChristoph Hellwig2022-07-011-2/+1
| |/ | | | | | | | | | | | | | | | | | | | | The ANDROID config symbol is only used to guard the binder config symbol and to inject completely random config changes. Remove it as it is obviously a bad idea. Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220629150102.1582425-2-hch@lst.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | Merge tag 'rcu.2022.07.26a' of ↵Linus Torvalds2022-08-0215-994/+1104
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu Pull RCU updates from Paul McKenney: - Documentation updates - Miscellaneous fixes - Callback-offload updates, perhaps most notably a new RCU_NOCB_CPU_DEFAULT_ALL Kconfig option that causes all CPUs to be offloaded at boot time, regardless of kernel boot parameters. This is useful to battery-powered systems such as ChromeOS and Android. In addition, a new RCU_NOCB_CPU_CB_BOOST kernel boot parameter prevents offloaded callbacks from interfering with real-time workloads and with energy-efficiency mechanisms - Polled grace-period updates, perhaps most notably making these APIs account for both normal and expedited grace periods - Tasks RCU updates, perhaps most notably reducing the CPU overhead of RCU tasks trace grace periods by more than a factor of two on a system with 15,000 tasks. The reduction is expected to increase with the number of tasks, so it seems reasonable to hypothesize that a system with 150,000 tasks might see a 20-fold reduction in CPU overhead - Torture-test updates - Updates that merge RCU's dyntick-idle tracking into context tracking, thus reducing the overhead of transitioning to kernel mode from either idle or nohz_full userspace execution for kernels that track context independently of RCU. This is expected to be helpful primarily for kernels built with CONFIG_NO_HZ_FULL=y * tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (98 commits) rcu: Add irqs-disabled indicator to expedited RCU CPU stall warnings rcu: Diagnose extended sync_rcu_do_polled_gp() loops rcu: Put panic_on_rcu_stall() after expedited RCU CPU stall warnings rcutorture: Test polled expedited grace-period primitives rcu: Add polled expedited grace-period primitives rcutorture: Verify that polled GP API sees synchronous grace periods rcu: Make Tiny RCU grace periods visible to polled APIs rcu: Make polled grace-period API account for expedited grace periods rcu: Switch polled grace-period APIs to ->gp_seq_polled rcu/nocb: Avoid polling when my_rdp->nocb_head_rdp list is empty rcu/nocb: Add option to opt rcuo kthreads out of RT priority rcu: Add nocb_cb_kthread check to rcu_is_callbacks_kthread() rcu/nocb: Add an option to offload all CPUs on boot rcu/nocb: Fix NOCB kthreads spawn failure with rcu_nocb_rdp_deoffload() direct call rcu/nocb: Invert rcu_state.barrier_mutex VS hotplug lock locking order rcu/nocb: Add/del rdp to iterate from rcuog itself rcu/tree: Add comment to describe GP-done condition in fqs loop rcu: Initialize first_gp_fqs at declaration in rcu_gp_fqs() rcu/kvfree: Remove useless monitor_todo flag rcu: Cleanup RCU urgency state for offline CPU ...
| * \ Merge branch 'ctxt.2022.07.05a' into HEADPaul E. McKenney2022-07-218-530/+57
| |\ \ | | | | | | | | | | | | ctxt.2022.07.05a: Linux-kernel memory model development branch.
| | * | context_tracking: Convert state to atomic_tFrederic Weisbecker2022-07-052-9/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Context tracking's state and dynticks counter are going to be merged in a single field so that both updates can happen atomically and at the same time. Prepare for that with converting the state into an atomic_t. [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
| | * | rcu/context-tracking: Move RCU-dynticks internal functions to context_trackingFrederic Weisbecker2022-07-053-362/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Move the core RCU eqs/dynticks functions to context tracking so that we can later merge all that code within context tracking. Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
| | * | rcu/context-tracking: Move deferred nocb resched to context trackingFrederic Weisbecker2022-07-051-13/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To prepare for migrating the RCU eqs accounting code to context tracking, split the last-resort deferred nocb resched from rcu_user_enter() and move it into a separate call from context tracking. Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
| | * | rcu/context_tracking: Move dynticks_nmi_nesting to context trackingFrederic Weisbecker2022-07-054-33/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The RCU eqs tracking is going to be performed by the context tracking subsystem. The related nesting counters thus need to be moved to the context tracking structure. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
| | * | rcu/context_tracking: Move dynticks_nesting to context trackingFrederic Weisbecker2022-07-053-17/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The RCU eqs tracking is going to be performed by the context tracking subsystem. The related nesting counters thus need to be moved to the context tracking structure. Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
| | * | rcu/context_tracking: Move dynticks counter to context trackingFrederic Weisbecker2022-07-054-33/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to prepare for merging RCU dynticks counter into the context tracking state, move the rcu_data's dynticks field to the context tracking structure. It will later be mixed within the context tracking state itself. [ paulmck: Move enum ctx_state into global scope. ] Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
| | * | rcu/context-tracking: Remove rcu_irq_enter/exit()Frederic Weisbecker2022-07-051-83/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now rcu_irq_enter/exit() is an unnecessary middle call between ct_irq_enter/exit() and nmi_irq_enter/exit(). Take this opportunity to remove the former functions and move the comments above them to the new entrypoints. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
| | * | context_tracking: Take idle eqs entrypoints over RCUFrederic Weisbecker2022-07-053-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The RCU dynticks counter is going to be merged into the context tracking subsystem. Start with moving the idle extended quiescent states entrypoints to context tracking. For now those are dumb redirections to existing RCU calls. [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
| | * | rcu: Apply noinstr to rcu_idle_enter() and rcu_idle_exit()Paul E. McKenney2022-06-201-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit applies the "noinstr" tag to the rcu_idle_enter() and rcu_idle_exit() functions, which are invoked from portions of the idle loop that cannot be instrumented. These tags require reworking the rcu_eqs_enter() and rcu_eqs_exit() functions that these two functions invoke in order to cause them to use normal assertions rather than lockdep. In addition, within rcu_idle_exit(), the raw versions of local_irq_save() and local_irq_restore() are used, again to avoid issues with lockdep in uninstrumented code. This patch is based in part on an earlier patch by Jiri Olsa, discussions with Peter Zijlstra and Frederic Weisbecker, earlier changes by Thomas Gleixner, and off-list discussions with Yonghong Song. Link: https://lore.kernel.org/lkml/20220515203653.4039075-1-jolsa@kernel.org/ Reported-by: Jiri Olsa <jolsa@kernel.org> Reported-by: Alexei Starovoitov <ast@kernel.org> Reported-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Yonghong Song <yhs@fb.com>
| | * | rcu: Dump rcuc kthread status for CPUs not reporting quiescent stateZqiang2022-06-201-28/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If the rcutree.use_softirq kernel boot parameter is disabled, then it is possible that a RCU CPU stall is due to the rcuc kthreads being starved of CPU time. There is currently no easy way to infer this from the RCU CPU stall warning output. This commit therefore adds a string of the form " rcuc=%ld jiffies(starved)" to a given CPU's output if the corresponding rcuc kthread has been starved for more than two seconds. [ paulmck: Eliminate extraneous space characters. ] Signed-off-by: Zqiang <qiang1.zhang@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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| *-------. \ \ Merge branches 'doc.2022.06.21a', 'fixes.2022.07.19a', 'nocb.2022.07.19a', ↵Paul E. McKenney2022-07-2115-455/+1105
| |\ \ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'poll.2022.07.21a', 'rcu-tasks.2022.06.21a' and 'torture.2022.06.21a' into HEAD doc.2022.06.21a: Documentation updates. fixes.2022.07.19a: Miscellaneous fixes. nocb.2022.07.19a: Callback-offload updates. poll.2022.07.21a: Polled grace-period updates. rcu-tasks.2022.06.21a: Tasks RCU updates. torture.2022.06.21a: Torture-test updates.
| | | | | | * | | refscale: Convert test_lock spinlock to raw_spinlockZqiang2022-06-211-9/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In kernels built with CONFIG_PREEMPT_RT=y, spinlocks are replaced by rt_mutex, which can sleep. This means that acquiring a non-raw spinlock in a critical section where preemption is disabled can trigger the following BUG: BUG: scheduling while atomic: ref_scale_reade/76/0x00000002 Preemption disabled at: ref_lock_section+0x16/0x80 Call Trace: <TASK> dump_stack_lvl+0x5b/0x82 dump_stack+0x10/0x12 __schedule_bug.cold+0x9c/0xad __schedule+0x839/0xc00 schedule_rtlock+0x22/0x40 rtlock_slowlock_locked+0x460/0x1350 rt_spin_lock+0x61/0xe0 ref_lock_section+0x29/0x80 rcu_scale_one_reader+0x52/0x60 ref_scale_reader+0x28d/0x490 kthread+0x128/0x150 ret_from_fork+0x22/0x30 </TASK> This commit therefore converts spinlock to raw_spinlock. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | | | | | * | | rcutorture: Handle failure of memory allocation functionsLi Qiong2022-06-211-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds warnings for allocation failure during the mem_dump_obj() tests. It also terminates these tests upon such failure. Signed-off-by: Li Qiong <liqiong@nfschina.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | | | | | * | | rcutorture: Fix ksoftirqd boosting timing and iterationFrederic Weisbecker2022-06-211-15/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The RCU priority boosting can fail in two situations: 1) If (nr_cpus= > maxcpus=), which means if the total number of CPUs is higher than those brought online at boot, then torture_onoff() may later bring up CPUs that weren't online on boot. Now since rcutorture initialization only boosts the ksoftirqds of the CPUs that have been set online on boot, the CPUs later set online by torture_onoff won't benefit from the boost, making RCU priority boosting fail. 2) The ksoftirqd kthreads are boosted after the creation of rcu_torture_boost() kthreads, which opens a window large enough for these rcu_torture_boost() kthreads to wait (despite running at FIFO priority) for ksoftirqds that are still running at SCHED_NORMAL priority. The issues can trigger for example with: ./kvm.sh --configs TREE01 --kconfig "CONFIG_RCU_BOOST=y" [ 34.968561] rcu-torture: !!! [ 34.968627] ------------[ cut here ]------------ [ 35.014054] WARNING: CPU: 4 PID: 114 at kernel/rcu/rcutorture.c:1979 rcu_torture_stats_print+0x5ad/0x610 [ 35.052043] Modules linked in: [ 35.069138] CPU: 4 PID: 114 Comm: rcu_torture_sta Not tainted 5.18.0-rc1 #1 [ 35.096424] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014 [ 35.154570] RIP: 0010:rcu_torture_stats_print+0x5ad/0x610 [ 35.198527] Code: 63 1b 02 00 74 02 0f 0b 48 83 3d 35 63 1b 02 00 74 02 0f 0b 48 83 3d 21 63 1b 02 00 74 02 0f 0b 48 83 3d 0d 63 1b 02 00 74 02 <0f> 0b 83 eb 01 0f 8e ba fc ff ff 0f 0b e9 b3 fc ff f82 [ 37.251049] RSP: 0000:ffffa92a0050bdf8 EFLAGS: 00010202 [ 37.277320] rcu: De-offloading 8 [ 37.290367] RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000001 [ 37.290387] RDX: 0000000000000000 RSI: 00000000ffffbfff RDI: 00000000ffffffff [ 37.290398] RBP: 000000000000007b R08: 0000000000000000 R09: c0000000ffffbfff [ 37.290407] R10: 000000000000002a R11: ffffa92a0050bc18 R12: ffffa92a0050be20 [ 37.290417] R13: ffffa92a0050be78 R14: 0000000000000000 R15: 000000000001bea0 [ 37.290427] FS: 0000000000000000(0000) GS:ffff96045eb00000(0000) knlGS:0000000000000000 [ 37.290448] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 37.290460] CR2: 0000000000000000 CR3: 000000001dc0c000 CR4: 00000000000006e0 [ 37.290470] Call Trace: [ 37.295049] <TASK> [ 37.295065] ? preempt_count_add+0x63/0x90 [ 37.295095] ? _raw_spin_lock_irqsave+0x12/0x40 [ 37.295125] ? rcu_torture_stats_print+0x610/0x610 [ 37.295143] rcu_torture_stats+0x29/0x70 [ 37.295160] kthread+0xe3/0x110 [ 37.295176] ? kthread_complete_and_exit+0x20/0x20 [ 37.295193] ret_from_fork+0x22/0x30 [ 37.295218] </TASK> Fix this with boosting the ksoftirqds kthreads from the boosting hotplug callback itself and before the boosting kthreads are created. Fixes: ea6d962e80b6 ("rcutorture: Judge RCU priority boosting on grace periods, not callbacks") Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | | | | | * | | rcuscale: Fix smp_processor_id()-in-preemptible warningsZqiang2022-06-211-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Systems built with CONFIG_DEBUG_PREEMPT=y can trigger the following BUG while running the rcuscale performance test: BUG: using smp_processor_id() in preemptible [00000000] code: rcu_scale_write/69 CPU: 0 PID: 66 Comm: rcu_scale_write Not tainted 5.18.0-rc7-next-20220517-yoctodev-standard+ caller is debug_smp_processor_id+0x17/0x20 Call Trace: <TASK> dump_stack_lvl+0x49/0x5e dump_stack+0x10/0x12 check_preemption_disabled+0xdf/0xf0 debug_smp_processor_id+0x17/0x20 rcu_scale_writer+0x2b5/0x580 kthread+0x177/0x1b0 ret_from_fork+0x22/0x30 </TASK> Reproduction method: runqemu kvm slirp nographic qemuparams="-m 4096 -smp 8" bootparams="isolcpus=2,3 nohz_full=2,3 rcu_nocbs=2,3 rcutree.dump_tree=1 rcuscale.shutdown=false rcuscale.gp_async=true" -d The problem is that the rcu_scale_writer() kthreads fail to set the PF_NO_SETAFFINITY flags, which causes is_percpu_thread() to assume that the kthread's affinity might change at any time, thus the BUG noted above. This commit therefore causes rcu_scale_writer() to set PF_NO_SETAFFINITY in its kthread's ->flags field, thus preventing this BUG. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | | | | | * | | rcutorture: Make failure indication note reader-batch overflowPaul E. McKenney2022-06-211-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The loop scanning the pipesummary[] array currently skips the last element, which means that the diagnostics ignore those rarest of situations, namely where some readers persist across more than ten grace periods, but all other readers avoid spanning a full grace period. This commit therefore adjusts the scan to include the last element of this array. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | | | | | * | | rcutorture: Fix memory leak in rcu_test_debug_objects()Zqiang2022-06-211-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kernel memory leak detector located the following: unreferenced object 0xffff95d941135b50 (size 16): comm "swapper/0", pid 1, jiffies 4294667610 (age 1367.451s) hex dump (first 16 bytes): f0 c6 c2 bd d9 95 ff ff 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000bc81d9b1>] kmem_cache_alloc_trace+0x2f6/0x500 [<00000000d28be229>] rcu_torture_init+0x1235/0x1354 [<0000000032c3acd9>] do_one_initcall+0x51/0x210 [<000000003c117727>] kernel_init_freeable+0x205/0x259 [<000000003961f965>] kernel_init+0x1a/0x120 [<000000001998f890>] ret_from_fork+0x22/0x30 This is caused by the rcu_test_debug_objects() function allocating an rcu_head structure, then failing to free it. This commit therefore adds the needed kfree() after the last use of this structure. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | | | | | * | | rcutorture: Simplify rcu_torture_read_exit_child() loopPaul E. McKenney2022-06-211-27/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The existing loop has an implicit manual loop that obscures the flow and requires an extra control variable. This commit makes this implicit loop explicit, thus saving several lines of code. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | | | | | * | | rcu/torture: Change order of warning and trace dumpAnna-Maria Behnsen2022-06-211-1/+2
| | | | | | |/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Dumping a big ftrace buffer could lead to a RCU stall. So there is the ftrace buffer and the stall information which needs to be printed. When there is additionally a WARN_ON() which describes the reason for the ftrace buffer dump and the WARN_ON() is executed _after_ ftrace buffer dump, the information get lost in the middle of the RCU stall information. Therefore print WARN_ON() message before dumping the ftrace buffer in rcu_torture_writer(). [ paulmck: Add tracing_off() to avoid cruft from WARN(). ] Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Reviewed-by: Benedikt Spranger <b.spranger@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | | | | * | | rcu-tasks: Use delayed_work to delay rcu_tasks_verify_self_tests()Waiman Long2022-06-211-5/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 2585014188d5 ("rcu-tasks: Be more patient for RCU Tasks boot-time testing") fixes false positive rcu_tasks verification check failure by repeating the test once every second until timeout using schedule_timeout_uninterruptible(). Since rcu_tasks_verify_selft_tests() is called from do_initcalls() as a late_initcall, this has the undesirable side effect of delaying other late_initcall's queued after it by a second or more. Fix this by instead using delayed_work to repeat the verification check. Fixes: 2585014188d5 ("rcu-tasks: Be more patient for RCU Tasks boot-time testing") Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| | | | | * | | rcu-tasks: Be more patient for RCU Tasks boot-time testingPaul E. McKenney2022-06-211-7/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The RCU-Tasks family of grace-period primitives can take some time to complete, and the amount of time can depend on the exact hardware and software configuration. Some configurations boot up fast enough that the RCU-Tasks verification process gets false-positive failures. This commit therefore allows up to 30 seconds for the grace periods to complete, with this value adjustable downwards using the rcupdate.rcu_task_stall_timeout kernel boot parameter. Reported-by: Matthew Wilcox <willy@infradead.org> Reported-by: Zhouyi Zhou <zhouzhouyi@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com> Tested-by: Mark Rutland <mark.rutland@arm.com>
| | | | | * | | rcu-tasks: Update commentsPaul E. McKenney2022-06-211-38/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit updates comments to reflect the changes in the series of commits that eliminated the full task-list scan. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Disable and enable CPU hotplug in same functionPaul E. McKenney2022-06-211-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rcu_tasks_trace_pregp_step() function invokes cpus_read_lock() to disable CPU hotplug, and a later call to the rcu_tasks_trace_postscan() function invokes cpus_read_unlock() to re-enable it. This was absolutely necessary in the past in order to protect the intervening scan of the full tasks list, but there is no longer such a scan. This commit therefore improves readability by moving the cpus_read_unlock() call to the end of the rcu_tasks_trace_pregp_step() function. This commit is a pure code-motion commit without any (intended) change in functionality. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Eliminate RCU Tasks Trace IPIs to online CPUsPaul E. McKenney2022-06-211-17/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, the RCU Tasks Trace grace-period kthread IPIs each online CPU using smp_call_function_single() in order to track any tasks currently in RCU Tasks Trace read-side critical sections during which the corresponding task has neither blocked nor been preempted. These IPIs are annoying and are also not strictly necessary because any task that blocks or is preempted within its current RCU Tasks Trace read-side critical section will be tracked on one of the per-CPU rcu_tasks_percpu structure's ->rtp_blkd_tasks list. So the only time that this is a problem is if one of the CPUs runs through a long-duration RCU Tasks Trace read-side critical section without a context switch. Note that the task_call_func() function cannot help here because there is no safe way to identify the target task. Of course, the task_call_func() function will be very useful later, when processing the list of tasks, but it needs to know the task. This commit therefore creates a cpu_curr_snapshot() function that returns a pointer the task_struct structure of some task that happened to be running on the specified CPU more or less during the time that the cpu_curr_snapshot() function was executing. If there was no context switch during this time, this function will return a pointer to the task_struct structure of the task that was running throughout. If there was a context switch, then the outgoing task will be taken care of by RCU's context-switch hook, and the incoming task was either already taken care during some previous context switch, or it is not currently within an RCU Tasks Trace read-side critical section. And in this latter case, the grace period already started, so there is no need to wait on this task. This new cpu_curr_snapshot() function is invoked on each CPU early in the RCU Tasks Trace grace-period processing, and the resulting tasks are queued for later quiescent-state inspection. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Maintain a count of tasks blocking RCU Tasks Trace grace periodPaul E. McKenney2022-06-211-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit maintains a new n_trc_holdouts counter that tracks the number of tasks blocking the RCU Tasks grace period. This counter is useful for debugging, and its value has been added to a diagostic message. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Stop RCU Tasks Trace from scanning full tasks listPaul E. McKenney2022-06-211-5/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit takes off the training wheels and relies only on scanning currently running tasks and tasks that have blocked or been preempted within their current RCU Tasks Trace read-side critical section. Before this commit, the time complexity of an RCU Tasks Trace grace period is O(T), where T is the number of tasks. After this commit, this time complexity is O(C+B), where C is the number of CPUs and B is the number of tasks that have blocked (or been preempted) at least once during their current RCU Tasks Trace read-side critical sections. Of course, if all tasks have blocked (or been preempted) at least once during their current RCU Tasks Trace read-side critical sections, this is still O(T), but current expectations are that RCU Tasks Trace read-side critical section will be short and that there will normally not be large numbers of tasks blocked within such a critical section. Dave Marchevsky kindly measured the effects of this commit on the RCU Tasks Trace grace-period latency and the rcu_tasks_trace_kthread task's CPU consumption per RCU Tasks Trace grace period over the course of a fixed test, all in milliseconds: Before After GP latency 22.3 ms stddev > 0.1 17.0 ms stddev < 0.1 GP CPU 2.3 ms stddev 0.3 1.1 ms stddev 0.2 This was on a system with 15,000 tasks, so it is reasonable to expect much larger savings on the systems on which this issue was first noted, given that they sport well in excess of 100,000 tasks. CPU consumption was measured using profiling techniques. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org> Tested-by: Dave Marchevsky <davemarchevsky@fb.com>
| | | | | * | | rcu-tasks: Stop RCU Tasks Trace from scanning idle tasksPaul E. McKenney2022-06-201-7/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that RCU scans both running tasks and tasks that have blocked within their current RCU Tasks Trace read-side critical section, there is no need for it to scan the idle tasks. After all, an idle loop should not be remain within an RCU Tasks Trace read-side critical section across exit from idle, and from a BPF viewpoint, functions invoked from the idle loop should not sleep. So only running idle tasks can be within RCU Tasks Trace read-side critical sections. This commit therefore removes the scan of the idle tasks from the rcu_tasks_trace_postscan() function. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Pull in tasks blocked within RCU Tasks Trace readersPaul E. McKenney2022-06-201-0/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit scans each CPU's ->rtp_blkd_tasks list, adding them to the list of holdout tasks. This will cause the current RCU Tasks Trace grace period to wait until these tasks exit their RCU Tasks Trace read-side critical sections. This commit will enable later work omitting the scan of the full task list. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Scan running tasks for RCU Tasks Trace readersPaul E. McKenney2022-06-201-11/+40
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A running task might be within an RCU Tasks Trace read-side critical section for any length of time, but will not be placed on any of the per-CPU rcu_tasks_percpu structure's ->rtp_blkd_tasks lists. Therefore any RCU Tasks Trace grace-period processing that does not scan the full task list must interact with the running tasks. This commit therefore causes the rcu_tasks_trace_pregp_step() function to IPI each CPU in order to place the corresponding task on the holdouts list and to record whether or not it was in an RCU Tasks Trace read-side critical section. Yes, it is possible to avoid adding it to that list if it is not a reader, but that would prevent the system from remembering that this task was in a quiescent state. Which is why the running tasks are unconditionally added to the holdout list. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Avoid rcu_tasks_trace_pertask() duplicate list additionsPaul E. McKenney2022-06-201-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds checks within rcu_tasks_trace_pertask() to avoid duplicate (and destructive) additions to the holdouts list. These checks will be required later due to the possibility of a given task having blocked while in an RCU Tasks Trace read-side critical section, but now running on a CPU. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Move rcu_tasks_trace_pertask() before rcu_tasks_trace_pregp_step()Paul E. McKenney2022-06-201-14/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a code-motion-only commit that moves rcu_tasks_trace_pertask() to precede rcu_tasks_trace_pregp_step(), so that the latter will be able to invoke the other without forward references. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Add blocked-task indicator to RCU Tasks Trace stall warningsPaul E. McKenney2022-06-201-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds a "B" indicator to the RCU Tasks Trace CPU stall warning when the task has blocked within its current read-side critical section. This serves as a debugging aid. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Untrack blocked RCU Tasks Trace at reader endPaul E. McKenney2022-06-201-6/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit causes rcu_read_unlock_trace() to check for the current task being on a per-CPU list within the rcu_tasks_percpu structure, and removes it from that list if so. This has the effect of curtailing tracking of a task that blocked within an RCU Tasks Trace read-side critical section once it exits that critical section. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Track blocked RCU Tasks Trace readersPaul E. McKenney2022-06-201-1/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit places any task that has ever blocked within its current RCU Tasks Trace read-side critical section on a per-CPU list within the rcu_tasks_percpu structure. Tasks are removed from this list when they exit by the exit_tasks_rcu_finish_trace() function. The purpose of this commit is to provide the information needed to eliminate the current scan of the full task list. This commit offsets the INT_MIN value for ->trc_reader_nesting with the new nesting level in order to avoid queueing tasks that are exiting their read-side critical sections. [ paulmck: Apply kernel test robot feedback. ] [ paulmck: Apply feedback from syzbot+9bb26e7c5e8e4fa7e641@syzkaller.appspotmail.com ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: syzbot <syzbot+9bb26e7c5e8e4fa7e641@syzkaller.appspotmail.com> Tested-by: "Zhang, Qiang1" <qiang1.zhang@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Add data structures for lightweight grace periodsPaul E. McKenney2022-06-201-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds fields to task_struct and to rcu_tasks_percpu that will be used to avoid the task-list scan for RCU Tasks Trace grace periods, and also initializes these fields. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Make RCU Tasks Trace stall warning handle idle offline tasksPaul E. McKenney2022-06-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a CPU is offline, its idle task can appear to be running, but it cannot be doing anything while CPU-hotplug operations are excluded. This commit takes advantage of that fact by making trc_check_slow_task() check for task_curr(t) && cpu_online(task_cpu(t)), and recording full information in that case. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Make RCU Tasks Trace stall warnings print full .b.need_qs fieldPaul E. McKenney2022-06-201-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, the RCU Tasks Trace CPU stall warning simply indicates whether or not the .b.need_qs field is zero. This commit shows the three permitted values and flags other values with either "!" or "?". This is a debugging aid. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Flag offline CPUs in RCU Tasks Trace stall warningsPaul E. McKenney2022-06-201-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit tags offline CPUs with "(offline)" in RCU Tasks Trace CPU stall warnings. This is a debugging aid. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Add slow-IPI indicator to RCU Tasks Trace stall warningsPaul E. McKenney2022-06-201-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds a "I" indicator to the RCU Tasks Trace CPU stall warning when an IPI directed to a task has thus far failed to arrive. This serves as a debugging aid. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Simplify trc_inspect_reader() QS logicPaul E. McKenney2022-06-201-6/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, trc_inspect_reader() does one check for nesting less than or equal to zero, then sorts out the distinctions within this single "if" statement. This commit simplifies the logic by providing one "if" statement for quiescent states (nesting of zero) and another "if" statement for transitioning from one nesting level to another or the outermost rcu_read_unlock_trace() (negative nesting). Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Make rcu_note_context_switch() unconditionally call rcu_tasks_qs()Paul E. McKenney2022-06-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit makes rcu_note_context_switch() unconditionally invoke the rcu_tasks_qs() function, as opposed to doing so only when RCU (as opposed to RCU Tasks Trace) urgently needs a grace period to end. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: RCU Tasks Trace grace-period kthread has implicit QSPaul E. McKenney2022-06-201-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Because the task driving the grace-period kthread is in quiescent state throughout, this commit excludes it from the list of tasks from which a quiescent state is needed. This does mean that attaching a sleepable BPF program to function in kernel/rcu/tasks.h is a bad idea, by the way. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Handle idle tasks for recently offlined CPUsPaul E. McKenney2022-06-201-8/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit identifies idle tasks for recently offlined CPUs as residing in a quiescent state. This is safe only because CPU-hotplug operations are excluded during these checks. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
| | | | | * | | rcu-tasks: Idle tasks on offline CPUs are in quiescent statesPaul E. McKenney2022-06-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Any idle task corresponding to an offline CPU is in an RCU Tasks Trace quiescent state. This commit causes rcu_tasks_trace_postscan() to ignore idle tasks for offline CPUs, which it can do safely due to CPU-hotplug operations being disabled. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>