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Darrick J. Wong 294f54f849
fserror: fix lockdep complaint when igrabbing inode
Christoph Hellwig reported a lockdep splat in generic/108:

 ================================
 WARNING: inconsistent lock state
 6.19.0+ #4827 Tainted: G                 N
 --------------------------------
 inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
 swapper/1/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
 ffff88811ed1b140 (&sb->s_type->i_lock_key#33){?.+.}-{3:3}, at: igrab+0x1a/0xb0
 {HARDIRQ-ON-W} state was registered at:
   lock_acquire+0xca/0x2c0
   _raw_spin_lock+0x2e/0x40
   unlock_new_inode+0x2c/0xc0
   xfs_iget+0xcf4/0x1080
   xfs_trans_metafile_iget+0x3d/0x100
   xfs_metafile_iget+0x2b/0x50
   xfs_mount_setup_metadir+0x20/0x60
   xfs_mountfs+0x457/0xa60
   xfs_fs_fill_super+0x6b3/0xa90
   get_tree_bdev_flags+0x13c/0x1e0
   vfs_get_tree+0x27/0xe0
   vfs_cmd_create+0x54/0xe0
   __do_sys_fsconfig+0x309/0x620
   do_syscall_64+0x8b/0xf80
   entry_SYSCALL_64_after_hwframe+0x76/0x7e
 irq event stamp: 139080
 hardirqs last  enabled at (139079): [<ffffffff813a923c>] do_idle+0x1ec/0x270
 hardirqs last disabled at (139080): [<ffffffff828a8d09>] common_interrupt+0x19/0xe0
 softirqs last  enabled at (139032): [<ffffffff8134a853>] __irq_exit_rcu+0xc3/0x120
 softirqs last disabled at (139025): [<ffffffff8134a853>] __irq_exit_rcu+0xc3/0x120

 other info that might help us debug this:
  Possible unsafe locking scenario:

        CPU0
        ----
   lock(&sb->s_type->i_lock_key#33);
   <Interrupt>
     lock(&sb->s_type->i_lock_key#33);

  *** DEADLOCK ***

 1 lock held by swapper/1/0:
  #0: ffff8881052c81a0 (&vblk->vqs[i].lock){-.-.}-{3:3}, at: virtblk_done+0x4b/0x110

 stack backtrace:
 CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G                 N  6.19.0+ #4827 PREEMPT(full)
 Tainted: [N]=TEST
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014
 Call Trace:
  <IRQ>
  dump_stack_lvl+0x5b/0x80
  print_usage_bug.part.0+0x22c/0x2c0
  mark_lock+0xa6f/0xe90
  __lock_acquire+0x10b6/0x25e0
  lock_acquire+0xca/0x2c0
  _raw_spin_lock+0x2e/0x40
  igrab+0x1a/0xb0
  fserror_report+0x135/0x260
  iomap_finish_ioend_buffered+0x170/0x210
  clone_endio+0x8f/0x1c0
  blk_update_request+0x1e4/0x4d0
  blk_mq_end_request+0x1b/0x100
  virtblk_done+0x6f/0x110
  vring_interrupt+0x59/0x80
  __handle_irq_event_percpu+0x8a/0x2e0
  handle_irq_event+0x33/0x70
  handle_edge_irq+0xdd/0x1e0
  __common_interrupt+0x6f/0x180
  common_interrupt+0xb7/0xe0
  </IRQ>

It looks like the concern here is that inode::i_lock is sometimes taken
in IRQ context, and sometimes it is held when going to IRQ context,
though it's a little difficult to tell since I think this is a kernel
from after the actual 6.19 release but before 7.0-rc1.

Either way, we don't need to take i_lock, because filesystems should
not report files to fserror if they're about to be freed or have not
yet been exposed to other threads, because the resulting fsnotify report
will be meaningless.

Therefore, bump inode::i_count directly and clarify the preconditions on
the inode being passed in.

Link: https://lore.kernel.org/linux-fsdevel/aY7BndIgQg3ci_6s@infradead.org/
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://patch.msgid.link/177148129564.716249.3069780698231701540.stgit@frogsfrogsfrogs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2026-02-19 09:12:08 +01:00
arch Loongarch: 2026-02-13 11:31:15 -08:00
block mm.git review status for linus..mm-stable 2026-02-12 11:32:37 -08:00
certs mm.git review status for linus..mm-nonmm-stable 2026-02-12 12:13:01 -08:00
crypto mm.git review status for linus..mm-nonmm-stable 2026-02-12 12:13:01 -08:00
Documentation Bootconfig for v7.0 2026-02-13 19:33:39 -08:00
drivers platform-drivers-x86 for v7.0-1 2026-02-13 15:39:15 -08:00
fs fserror: fix lockdep complaint when igrabbing inode 2026-02-19 09:12:08 +01:00
include fsnotify: drop unused helper 2026-02-19 09:12:05 +01:00
init mm.git review status for linus..mm-nonmm-stable 2026-02-12 12:13:01 -08:00
io_uring for-7.0/io_uring-zcrx-large-buffers-20260206 2026-02-12 15:07:50 -08:00
ipc mm.git review status for linus..mm-nonmm-stable 2026-02-12 12:13:01 -08:00
kernel unshare: fix unshare_fs() handling 2026-02-18 14:04:51 +01:00
lib Bootconfig for v7.0 2026-02-13 19:33:39 -08:00
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 Three MM hotfixes, all three are cc:stable. 2026-02-13 12:13:27 -08:00
net virtio,vhost,vdpa: features, fixes 2026-02-13 12:02:18 -08:00
rust configfs changes for v7.0 2026-02-12 14:01:38 -08:00
samples configfs changes for v7.0 2026-02-12 14:01:38 -08:00
scripts virtio,vhost,vdpa: features, fixes 2026-02-13 12:02:18 -08:00
security mm.git review status for linus..mm-nonmm-stable 2026-02-12 12:13:01 -08:00
sound mm.git review status for linus..mm-nonmm-stable 2026-02-12 12:13:01 -08:00
tools Bootconfig for v7.0 2026-02-13 19:33:39 -08:00
usr kbuild: uapi: drop dependency on CC_CAN_LINK 2026-01-16 15:02:11 -07:00
virt Merge tag 'kvm-x86-pmu-6.20' of https://github.com/kvm-x86/linux into HEAD 2026-02-11 12:45:40 -05:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap Landlock update for v7.0-rc1 2026-02-11 15:57:08 -08:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS Networking changes for 7.0 2026-02-11 19:31:52 -08:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS tracing updates for 7.0: 2026-02-13 19:25:16 -08:00
Makefile Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
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