Linus Torvalds 83684c4e4d Merge tag 'rcu.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux
Pull RCU updates from Paul McKenney:
 "Make expedited grace periods expedite normal RCU callbacks

  Miscellaneous fixes:
   - Improve diagnostic output with character task states
   - Mark accesses to inform KCSAN of concurrency design
   - Move from kmalloc() to kmalloc_obj()
   - Documentation updates
   - Improve handling of RCU deferred quiescent states
   - Clean up unused function arguments and structure fields
   - Reduce show_rcu_gp_kthreads() stack space

  Tasks RCU updates:
   - Clean up after SRCU re-implementation of Tasks Trace RCU
   - Mark accesses to inform KCSAN of concurrency design
   - Add ->lazy_timer status to diagnostic output
   - Remove an unnecessary memory barrier
   - Fix a data race, courtesy of KCSAN
   - Documentation updates
   - Convert cond_resched_tasks_rcu_qs() from macro to static inline
     function

  SRCU updates:
   - Add Rust helpers for SRCU
   - Avoid losing queued work at cleanup_srcu_struct() time

  Torture-test updates:
   - Preparation work for immediate RCU priority deboosting
   - Test RCU readers from real interrupt handlers (as opposed to
     softirq)
   - Simplify code through use of cpumask_next_wrap()
   - Improve diagnostic output with character task states
   - Add rcutorture.nwriters parameter to allow lightweight stall
     testing, and rcutorture.stall_only to make doing so easier
   - Test an RCU Tasks Trace grace period implying an RCU grace period
   - Make RCU Tasks Trace torturing track reader batches
   - Fix a data race, courtesy of KCSAN
   - Plug a shuffle_tmp_mask memory leak on kthread spawn failure"

* tag 'rcu.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (59 commits)
  rcu: Add closing parenthesis in comment in rcu_read_unlock_strict()
  rcutorture: Make {,s}rcu_read_delay() better handle forward-progress testing
  rcutorture: Announce declining to forward-progress test
  torture: Don't leak shuffle_tmp_mask when shuffler kthread fails to start
  rcutorture: Use this_cpu_inc() for rcu_torture_count[] and rcu_torture_batch[]
  rcutorture: Make RCU Tasks Trace track Reader Batches
  rcutorture: Test RCU Tasks Trace GP implying RCU GP
  rcutorture: Add a stall_only module parameter
  rcutorture: Add nwriters module parameter
  rcutorture: Use task_state_to_char() for task-state reporting
  rcutorture: Use cpumask_next_wrap() in rcu_torture_preempt()
  rcutorture: Test RCU readers from hardware interrupt handlers
  rcutorture: Check for immediate deboosting at reader end
  srcu: Queue sdp->work when the delay timer is successfully deleted
  rcu-tasks: Convert cond_resched_tasks_rcu_qs() to static inline
  rcu-tasks: Fix some comments for call_rcu_tasks() and call_rcu_tasks_rude()
  rcu-tasks: Rename tasks_rcu_exit_srcu_stall_timer to tasks_rcu_exit_stall_timer
  rcu: Mark interrupts-enabled accesses to rdp->cpu_no_qs.s
  rcu: Reduce stack usage in show_rcu_gp_kthreads()
  rcu: Mark accesses to ->rcu_urgent_qs and ->rcu_need_heavy_qs
  ...
2026-08-23 18:00:22 -07:00
2026-01-26 19:07:09 -08:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2026-07-15 10:51:29 -06:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer: Getting started with kernel development
* Academic Researcher: Studying kernel internals and architecture
* Security Expert: Hardening and vulnerability analysis
* Backport/Maintenance Engineer: Maintaining stable kernels
* System Administrator: Configuring and troubleshooting
* Maintainer: Leading subsystems and reviewing patches
* Hardware Vendor: Writing drivers for new hardware
* Distribution Maintainer: Packaging kernels for distros
* AI Coding Assistant: LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst
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