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Andrii Nakryiko 7f9ce282da Merge branch 'bpf-implement-stack_map_get_build_id_offset_sleepable'
Ihor Solodrai says:

====================
bpf: Implement stack_map_get_build_id_offset_sleepable()

The series introduces stack_map_get_build_id_offset_sleepable(),
fixing a gap with parsing build_id in sleepable context in stackmap.c

In particular, this fixes a deadlock in
stack_map_get_build_id_offset() doing a blocking __kernel_read(),
which happens since commit 777a8560fd ("lib/buildid: use
__kernel_read() for sleepable context").

See previous revisions for more details.
---

v6->v7:
  * Addressed feedback from Andrii (mostly patch #2):
    * implement proper CONFIG_PER_VMA_LOCK=n support, following a
      VMA locking pattern similar to one used in PROCMAP_QUERY
    * change the contract of stack_map_lock_vma(): if a non-NULL VMA
      is returned, then a read lock is held
      * remove now unnecessary vma_locked flag
    * and various other nits
  * Add vma_is_anonymous() checks where appropriate (AIs)
v6: https://lore.kernel.org/bpf/20260521225022.2695755-1-ihor.solodrai@linux.dev/

v5->v6:
  * Misc refactoring (Andrii):
    * add stack_map_build_id_set_valid() helper
    * simplify control flow in stack_map_get_build_id_offset_sleepable()
v5: https://lore.kernel.org/bpf/20260515005244.1333013-1-ihor.solodrai@linux.dev/

v4->v5:
  * Add comments explaining mmap_read_trylock() (Shakeel)
  * Rebase on bpf-next (Alexei)
v4: https://lore.kernel.org/bpf/20260514184727.1067141-1-ihor.solodrai@linux.dev/

v3->v4:
  * Change Fixes tag in patch #2 (AI)
  * Nit in caching implementation (Mykyta)
v3: https://lore.kernel.org/bpf/20260512032906.2670326-1-ihor.solodrai@linux.dev/

v2->v3:
  * Split patch #2 in two: stack_map_get_build_id_offset_sleepable()
    implementation, and then introduce caching
  * Drop taking mmap_lock if CONFIG_PER_VMA_LOCK=n, fall back to raw
    IPs instead
  * Cache vm_{start,end} in addition to prev_file (Mykyta)
v2: https://lore.kernel.org/bpf/20260409010604.1439087-1-ihor.solodrai@linux.dev/

v1->v2:
  * Addressed feedback from Puranjay:
    * split out a small refactoring patch
    * use mmap_read_trylock()
    * take into account CONFIG_PER_VMA_LOCK
    * replace find_vma() with vma_lookup()
    * cache prev_build_id to avoid re-parsing the same file
  * Snapshot vm_pgoff and vm_start before unlocking (AI)
  * To avoid repetitive unlocking statements, introduce struct
    stack_map_vma_lock to hold relevant lock state info and add an
    unlock helper
v1: https://lore.kernel.org/bpf/20260407223003.720428-1-ihor.solodrai@linux.dev/

---
====================

Link: https://patch.msgid.link/20260525223948.1920986-1-ihor.solodrai@linux.dev
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
History 2026-05-28 14:58:14 -07:00
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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