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Alexandra Winter aa5ec571b9 net/iucv: Add lock nesting annotation in iucv_sock_close()
iucv_sock_close() acquires lock_sock(sk) and then, when the socket is in
IUCV_LISTEN state, calls iucv_sock_cleanup_listen() which acquires
lock_sock(child_sk) for each pending child socket. Moreover
iucv_sock_close(child_sk) is called on the pending child sockets.

Avoid lockdep warning by using lock_sock_nested() in iucv_sock_close().
Split off __iucv_sock_close(), so iucv_sock_cleanup_listen() can call it
without nesting.

This is a missing lockdep annotation - not a real deadlock.

Example warning:
[ 6690.906930] ============================================
[ 6690.906935] WARNING: possible recursive locking detected
[ 6690.906942] 7.3.0-rc1net_KCSAN_KASAN-00240-g641d03105cc0 #23 Not tainted
[ 6690.906948] --------------------------------------------
[ 6690.906953] afiucv_test_loc/5183 is trying to acquire lock:
[ 6690.906959] 000601ad13f20a78 (sk_lock-IUCV){+.+.}-{0:0}, at: iucv_accept_dequeue+0xdc/0x340 [af_iucv]
[ 6690.906984]
               but task is already holding lock:
[ 6690.906989] 000601ad1c115278 (sk_lock-IUCV){+.+.}-{0:0}, at: iucv_sock_close+0x82/0x7d0 [af_iucv]
[ 6690.907006]
               other info that might help us debug this:
[ 6690.907010]  Possible unsafe locking scenario:

[ 6690.907014]        CPU0
[ 6690.907018]        ----
[ 6690.907021]   lock(sk_lock-IUCV);
[ 6690.907028]   lock(sk_lock-IUCV);
[ 6690.907034]
                *** DEADLOCK ***

[ 6690.907038]  May be due to missing lock nesting notation

[ 6690.907043] locks held by afiucv_test_loc/5183: 2, last CPU#0:
[ 6690.907085]  #0: 000601ad137a5550 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: __sock_release+0x7e/0x230
[ 6690.907109]  #1: 000601ad1c115278 (sk_lock-IUCV){+.+.}-{0:0}, at: iucv_sock_close+0x82/0x7d0 [af_iucv]
[ 6690.907127]
               stack backtrace:
[ 6690.907135] CPU: 0 UID: 0 PID: 5183 Comm: afiucv_test_loc Kdump: loaded Not tainted 7.3.0-rc1net_KCSAN_KASAN-00240-g641d03105cc0 #23 PREEMPT
[ 6690.907140] Hardware name: IBM 8561 T01 703 (z/VM 7.4.0)
[ 6690.907142] Call Trace:
[ 6690.907144]  [<00061ab555fd6208>] dump_stack_lvl+0xe8/0x140
[ 6690.907151]  [<00061ab55623a110>] print_deadlock_bug+0x340/0x350
[ 6690.907156]  [<00061ab55623f768>] __lock_acquire+0x11b8/0x15d0
[ 6690.907159]  [<00061ab55623fc9c>] lock_acquire.part.0+0x11c/0x290
[ 6690.907162]  [<00061ab55623fec4>] lock_acquire+0xb4/0x1e0
[ 6690.907164]  [<00061ab5580d6b96>] lock_sock_nested+0x46/0xf0
[ 6690.907167]  [<00061ab4d66e38dc>] iucv_accept_dequeue+0xdc/0x340 [af_iucv]
[ 6690.907171]  [<00061ab4d66e541c>] iucv_sock_close+0xdc/0x7d0 [af_iucv]
[ 6690.907174]  [<00061ab4d66e5b62>] iucv_sock_release+0x52/0x130 [af_iucv]
[ 6690.907177]  [<00061ab5580c5b24>] __sock_release+0xa4/0x230
[ 6690.907180]  [<00061ab5580c5cdc>] sock_close+0x2c/0x40
[ 6690.907183]  [<00061ab556ac7a00>] __fput+0x2f0/0x880
[ 6690.907187]  [<00061ab556ac8cc0>] fput_close_sync+0xd0/0x1c0
[ 6690.907189]  [<00061ab556abbc70>] __s390x_sys_close+0x90/0xf0
[ 6690.907192]  [<00061ab55894df0e>] __do_syscall+0x1be/0x5a0
[ 6690.907196]  [<00061ab558976a7a>] system_call+0x72/0x90
[ 6690.907200] INFO: lockdep is turned off.

Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260910162919.2100124-1-wintera@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
History 2026-09-14 18:52:33 -07:00
arch * AMD device topology and machine check fixes 2026-09-08 12:54:56 -07:00
block block: save page offset gaps in cloned bio 2026-09-01 08:42:34 -06:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto This push fixes a memory allocation overrun in crypto acomp. 2026-08-28 09:28:40 -07:00
Documentation dt-bindings: net: x-powers: add AC200/AC300 EPHY packages 2026-09-14 18:44:00 -07:00
drivers octeontx2-pf: report port connector type in ethtool link ksettings 2026-09-14 18:45:32 -07:00
fs smb client fixes for v7.3-rc3 2026-09-10 14:03:48 -07:00
include net: rtnetlink: add pacing_offload attribute to net_device 2026-09-14 17:42:33 -07:00
init vfs-7.3-rc3.fixes 2026-09-09 09:38:03 -07:00
io_uring treewide: refresh kmalloc_obj() conversions 2026-09-04 21:37:00 -07:00
ipc mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
kernel Summary 2026-09-10 09:36:56 -07:00
lib treewide: refresh kmalloc_obj() conversions 2026-09-04 21:37:00 -07:00
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 treewide: refresh kmalloc_obj() conversions 2026-09-04 21:37:00 -07:00
net net/iucv: Add lock nesting annotation in iucv_sock_close() 2026-09-14 18:52:33 -07:00
rust rust: pci: reject IRQ vector indices that do not fit in u32 2026-09-01 18:21:01 +02:00
samples tracing fixes for v7.3: 2026-08-30 09:22:00 -07:00
scripts Coccinelle patches for Linux v7.3 2026-08-30 10:42:40 -07:00
security landlock: Test trace path output boundaries 2026-09-08 11:49:39 +02:00
sound treewide: refresh kmalloc_obj() conversions 2026-09-04 21:37:00 -07:00
tools selftests: drv-net: extend so_txtime with hw offload 2026-09-14 17:42:34 -07:00
usr usr: Correct a spelling by changing a letter 2026-08-05 14:51:58 +02:00
virt Arm: 2026-08-25 11:48:04 -07:00
.clang-format drm/bridge: rename drm_for_each_bridge_in_chain_scoped() to drm_for_each_bridge_in_chain() 2026-07-14 17:55:51 +02:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add Nathan Chancellor 2026-08-03 21:10:12 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore SPDX patches for 7.2-rc1 2026-06-22 12:06:22 -07:00
.mailmap Nothing too exciting, usual stream of fixes. 2026-09-10 14:07:48 -07:00
.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 Driver core fixes for 7.3-rc2 2026-09-05 11:59:05 -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 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-09-10 15:14:05 -07:00
Makefile Linux 7.3-rc2 2026-09-06 15:07:20 -07:00
README README: remove out of place emdashes 2026-07-15 10:51:29 -06:00

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