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Linus Torvalds a53fcff8fc Updates for the NOHZ subsystem:
- Fix a long standing TOCTOU in get_cpu_sleep_time_us()
 
   - Make the CPU offline NOHZ handling more robust by disabling NOHZ on the
     outgoing CPU early instead of creating unneeded state which needs to be
     undone.
 
   - Unify idle CPU time accounting instead of having two different
     accounting mechanisms. These two different mechanisms are not really
     independent, but the different properties can in the worst case cause
     that gloabl idle time can be observed going backwards.
 
   - Consolidate the idle/iowait time retrieval interfaces instead of
     converting back and forth between them.
 
   - Make idle interrupt time accounting more robust. The original code
     assumes that interrupt time accouting is enabled and therefore stops
     elapsing idle time while an interrupt is handled in NOHZ dyntick
     state. That assumption is not correct as interrupt time accounting can
     be disabled at compile and runtime.
 
   - Fix an accounting error between dyntick idle time and dyntick idle
     steal time. The stolen time is not accounted and therefore idle time
     becomes inaccurate. The stolen time is now accounted after the fact as
     there is no way to predict the steal time upfront.
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Merge tag 'timers-nohz-2026-06-13' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip

Pull NOHZ updates from Thomas Gleixner:

 - Fix a long standing TOCTOU in get_cpu_sleep_time_us()

 - Make the CPU offline NOHZ handling more robust by disabling NOHZ on
   the outgoing CPU early instead of creating unneeded state which needs
   to be undone.

 - Unify idle CPU time accounting instead of having two different
   accounting mechanisms. These two different mechanisms are not really
   independent, but the different properties can in the worst case cause
   that gloabl idle time can be observed going backwards.

 - Consolidate the idle/iowait time retrieval interfaces instead of
   converting back and forth between them.

 - Make idle interrupt time accounting more robust. The original code
   assumes that interrupt time accouting is enabled and therefore stops
   elapsing idle time while an interrupt is handled in NOHZ dyntick
   state. That assumption is not correct as interrupt time accounting
   can be disabled at compile and runtime.

 - Fix an accounting error between dyntick idle time and dyntick idle
   steal time. The stolen time is not accounted and therefore idle time
   becomes inaccurate. The stolen time is now accounted after the fact
   as there is no way to predict the steal time upfront.

* tag 'timers-nohz-2026-06-13' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip:
  sched/cputime: Handle dyntick-idle steal time correctly
  sched/cputime: Handle idle irqtime gracefully
  sched/cputime: Provide get_cpu_[idle|iowait]_time_us() off-case
  tick/sched: Consolidate idle time fetching APIs
  tick/sched: Account tickless idle cputime only when tick is stopped
  tick/sched: Remove unused fields
  tick/sched: Move dyntick-idle cputime accounting to cputime code
  tick/sched: Remove nohz disabled special case in cputime fetch
  tick/sched: Unify idle cputime accounting
  s390/time: Prepare to stop elapsing in dynticks-idle
  powerpc/time: Prepare to stop elapsing in dynticks-idle
  sched/cputime: Correctly support generic vtime idle time
  sched/cputime: Remove superfluous and error prone kcpustat_field() parameter
  sched/idle: Handle offlining first in idle loop
  tick/sched: Fix TOCTOU in nohz idle time fetch
2026-06-15 13:48:52 +05:30
arch Updates for the NOHZ subsystem: 2026-06-15 13:48:52 +05:30
block block-7.1-20260529 2026-05-29 10:41:07 -07:00
certs Clang build fixes for 7.1 2026-04-24 09:29:51 -07:00
crypto crypto/krb5, rxrpc: Fix lack of pre-decrypt/pre-verify length checks 2026-05-20 16:36:45 -07:00
Documentation Updates for clocksource/clockevent drivers: 2026-06-15 13:34:03 +05:30
drivers Updates for the NOHZ subsystem: 2026-06-15 13:48:52 +05:30
fs Updates for the NOHZ subsystem: 2026-06-15 13:48:52 +05:30
include Updates for the NOHZ subsystem: 2026-06-15 13:48:52 +05:30
init Rust changes for v7.2 2026-06-15 09:25:48 +05:30
io_uring io_uring-7.1-20260611 2026-06-12 10:49:59 -07:00
ipc kernel-7.2-rc1.misc 2026-06-15 03:05:50 +05:30
kernel Updates for the NOHZ subsystem: 2026-06-15 13:48:52 +05:30
lib vfs-7.2-rc1.misc 2026-06-15 03:59:45 +05:30
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm Driver core changes for 7.2-rc1 2026-06-15 12:41:17 +05:30
net Updates for the time/timer core subsystem: 2026-06-15 13:39:12 +05:30
rust Driver core changes for 7.2-rc1 2026-06-15 12:41:17 +05:30
samples Driver core changes for 7.2-rc1 2026-06-15 12:41:17 +05:30
scripts Updates for the NOHZ subsystem: 2026-06-15 13:48:52 +05:30
security Kbuild / Kconfig changes for 7.2 2026-06-15 05:01:15 +05:30
sound ASoC: Fixes for v7.1 2026-06-11 21:29:47 +02:00
tools Updates for the time/timer core subsystem: 2026-06-15 13:39:12 +05:30
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt vfs-7.2-rc1.misc 2026-06-15 03:59:45 +05:30
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add Askar 2026-04-15 02:15:02 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Rust changes for v7.2 2026-06-15 09:25:48 +05:30
.mailmap MAINTAINERS: update Baoquan He's email address 2026-06-03 16:25:50 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml
COPYING
CREDITS Delete some obsolete networking code 2026-04-24 09:41:58 -07:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Two small updates to the SMP/hotplug subsystem: 2026-06-15 13:30:04 +05:30
Makefile Rust changes for v7.2 2026-06-15 09:25:48 +05:30
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

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