Filipe Manana 598c10a9e9 btrfs: turn extent_io_tree_panic() into a macro for better error reporting
When extent_io_tree_panic() is called we get a stace trace that is not
very useful since the error message reports the location inside the
extent_io_tree_panic() function and not in the caller of the function.

Example:

  [ 7830.424291] BTRFS critical (device sdb): panic in extent_io_tree_panic:334: extent io tree error on add_extent_changeset state start 4083712 end 4112383 (errno=1 unknown)
  [ 7830.426816] ------------[ cut here ]------------
  [ 7830.427581] kernel BUG at fs/btrfs/extent-io-tree.c:334!
  [ 7830.428495] Oops: invalid opcode: 0000 [#1] SMP PTI
  [ 7830.429318] CPU: 5 UID: 0 PID: 1451600 Comm: fsstress Not tainted 7.0.0-rc2-btrfs-next-227+ #1 PREEMPT(full)
  [ 7830.430899] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
  [ 7830.432771] RIP: 0010:extent_io_tree_panic+0x41/0x43 [btrfs]
  [ 7830.433815] Code: 75 0a 48 8b (...)
  [ 7830.436849] RSP: 0018:ffffd2334f4a3b68 EFLAGS: 00010246
  [ 7830.437668] RAX: 0000000000000000 RBX: 00000000003ebfff RCX: 0000000000000000
  [ 7830.438801] RDX: ffffffffc08d4368 RSI: ffffffffbb6ce475 RDI: ffff896501d6b780
  [ 7830.439671] RBP: 0000000000001000 R08: 0000000000000000 R09: 00000000ffefffff
  [ 7830.440575] R10: 0000000000000000 R11: 0000000000000003 R12: 0000000000000000
  [ 7830.441458] R13: ffff896547374c08 R14: 00000000003effff R15: ffff896547374c08
  [ 7830.442333] FS:  00007f3e252af0c0(0000) GS:ffff896c6185d000(0000) knlGS:0000000000000000
  [ 7830.443326] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [ 7830.444047] CR2: 00007f3e252ad000 CR3: 0000000113b0a004 CR4: 0000000000370ef0
  [ 7830.444905] Call Trace:
  [ 7830.445229]  <TASK>
  [ 7830.445557]  btrfs_clear_extent_bit_changeset.cold+0x43/0x80 [btrfs]
  [ 7830.446543]  btrfs_clear_record_extent_bits+0x19/0x20 [btrfs]
  [ 7830.447308]  qgroup_free_reserved_data+0xf9/0x170 [btrfs]
  [ 7830.448040]  btrfs_buffered_write+0x368/0x8e0 [btrfs]
  [ 7830.448707]  btrfs_direct_write+0x1a5/0x480 [btrfs]
  [ 7830.449396]  btrfs_do_write_iter+0x18c/0x210 [btrfs]
  [ 7830.450167]  vfs_write+0x21f/0x450
  [ 7830.450662]  ksys_write+0x5f/0xd0
  [ 7830.451092]  do_syscall_64+0xe9/0xf20
  [ 7830.451610]  entry_SYSCALL_64_after_hwframe+0x76/0x7e

Change extent_io_tree_panic() to a macro so that we get a report that
gives the exact place where the error happens.

Example after this change:

  [63677.406061] BTRFS critical (device sdc): panic in btrfs_clear_extent_bit_changeset:744: extent io tree error on add_extent_changeset state start 1818624 end 1830911 (errno=1 unknown)
  [63677.410055] ------------[ cut here ]------------
  [63677.410910] kernel BUG at fs/btrfs/extent-io-tree.c:744!
  [63677.411918] Oops: invalid opcode: 0000 [#1] SMP PTI
  [63677.413032] CPU: 0 UID: 0 PID: 13028 Comm: fsstress Not tainted 7.0.0-rc2-btrfs-next-227+ #1 PREEMPT(full)
  [63677.415139] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
  [63677.417283] RIP: 0010:btrfs_clear_extent_bit_changeset.cold+0xcd/0x10c [btrfs]
  [63677.418676] Code: 8b 37 48 8b (...)
  [63677.421917] RSP: 0018:ffffd2290a417b30 EFLAGS: 00010246
  [63677.422824] RAX: 0000000000000000 RBX: 00000000001befff RCX: 0000000000000000
  [63677.424320] RDX: ffffffffc0970348 RSI: ffffffffa92ce475 RDI: ffff8897ded9dc80
  [63677.429772] RBP: 0000000000001000 R08: 0000000000000000 R09: 00000000ffefffff
  [63677.430787] R10: 0000000000000000 R11: 0000000000000003 R12: 0000000000000000
  [63677.431818] R13: ffff8897966655d8 R14: 00000000001bffff R15: ffff8897966655d8
  [63677.432764] FS:  00007f5c074c50c0(0000) GS:ffff889ef3b1d000(0000) knlGS:0000000000000000
  [63677.433940] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [63677.434787] CR2: 00007f5c074c3000 CR3: 000000014b9de002 CR4: 0000000000370ef0
  [63677.435960] Call Trace:
  [63677.436432]  <TASK>
  [63677.436838]  btrfs_clear_record_extent_bits+0x19/0x20 [btrfs]
  [63677.437980]  qgroup_free_reserved_data+0xf9/0x170 [btrfs]
  [63677.439070]  btrfs_buffered_write+0x368/0x8e0 [btrfs]
  [63677.439889]  btrfs_do_write_iter+0x1a8/0x210 [btrfs]
  [63677.441460]  do_iter_readv_writev+0x145/0x240
  [63677.446309]  vfs_writev+0x120/0x3b0
  [63677.446878]  ? __do_sys_newfstat+0x33/0x60
  [63677.447759]  ? do_pwritev+0x8a/0xd0
  [63677.449119]  do_pwritev+0x8a/0xd0
  [63677.452342]  do_syscall_64+0xe9/0xf20
  [63677.452961]  entry_SYSCALL_64_after_hwframe+0x76/0x7e

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-04-07 18:56:03 +02:00
2026-01-26 19:07:09 -08:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2026-04-05 15:26:23 -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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