Chao Yu 46d4246d8d f2fs: use f2fs_{down, up}_(read, write}_trace() for nat_tree_lock
Under heavy workloads or during background GC/fallocate operations,
nat_tree_lock can experience high lock contention between background
readers (e.g. f2fs_get_node_info() in gc_data_segment) and writers
(e.g. flush_nat_entries, set_node_addr, shrinker).

[375067.327986][T13777]  schedule+0x4c/0x114
[375067.327997][T13777]  f2fs_get_node_info+0x438/0x5c4
[375067.328002][T13777]  f2fs_get_inode_page+0x1e0/0x3f0
[375067.328013][T13777]  f2fs_iget+0x88/0x1180
[375067.328024][T13777]  f2fs_lookup+0x168/0x3a8
[375067.328035][T13777]  path_openat+0xa28/0x1b04
[375067.328046][T13777]  do_filp_open+0xac/0x130
[375067.328056][T13777]  do_sys_openat2+0x140/0x21c
[375067.328066][T13777]  __arm64_sys_openat+0x70/0x9c

[375067.330299][T13777]  schedule+0x4c/0x114
[375067.330310][T13777]  schedule_preempt_disabled+0x24/0x40
[375067.330321][T13777]  rwsem_down_write_slowpath+0x3b4/0x9d0
[375067.330332][T13777]  down_write+0x98/0x170
[375067.330343][T13777]  set_node_addr+0x74/0x4b4
[375067.330354][T13777]  f2fs_new_node_page+0xb0/0x280
[375067.330444][T13777]  f2fs_new_inode_page+0x3c/0x64
[375067.330455][T13777]  f2fs_init_inode_metadata+0x4c/0x47c
[375067.330461][T13777]  f2fs_add_regular_entry+0x258/0x5b8
[375067.330471][T13777]  f2fs_add_dentry+0x100/0x158
[375067.330476][T13777]  f2fs_do_add_link+0x84/0x140
[375067.330487][T13777]  f2fs_create+0xec/0x250

[375067.331759][T13777]  schedule+0x4c/0x114
[375067.331770][T13777]  f2fs_down_read+0x9c/0xc4
[375067.331781][T13777]  f2fs_need_inode_block_update+0x20/0x10c
[375067.331792][T13777]  f2fs_do_sync_file+0x478/0x830
[375067.331802][T13777]  f2fs_sync_file+0x2c/0x40

This patch converts nat_tree_lock to use the f2fs_{down,up}_{read,write}_trace
infrastructure.

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2026-08-21 23:42:31 +00:00
2026-01-26 19:07:09 -08:00
2022-09-28 09:02:20 +02:00
2026-07-14 16:34:04 +02:00
2025-02-19 14:53:27 -07:00
2026-07-26 14:45:48 -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
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