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Jakub Kicinski ddef4c2d6d net: only give queue leasing devices a separate instance lock class
Commit b6f74dff6d ("net: use two lockdep classes for the netdev
instance lock") put every device without a parent in the virtual class.
It also restricted the locking order for the virtual class, because
queue leasing has hard requirements on the exact order.

This bites us back on bond, which is "virtual" and needs to be taken
before taking the locks of the lowers. NIPA hit the following on the
new test I recently posted for XDP+bond:

  WARNING: possible circular locking dependency detected
  ------------------------------------------------------
  python3/18635 is trying to acquire lock:
  ff11000120b8ce30 (&dev->lock){+.+.}-{4:4}, at:
  netdev_put_lock+0x2d/0x1a0

  but task is already holding lock:
  ff110001ef77ae30 (&netdev_virt_instance_lock_key){+.+.}-{4:4}, at:
  netdev_put_lock+0x2d/0x1a0

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #1 (&netdev_virt_instance_lock_key){+.+.}-{4:4}:
         __mutex_lock+0x1ae/0x1f10
         xdp_set_features_flag+0x2b/0x50
         bond_xdp_set_features+0x1eb/0x360
         bond_netdev_event+0x13f/0x300
         notifier_call_chain+0xae/0x300
         call_netdevice_notifiers+0x70/0xa0
         bnxt_xdp_set+0x2f6/0x620
         netif_xdp_propagate+0x503/0xc60
         dev_xdp_propagate+0xa1/0x230
         bond_xdp_set+0x234/0x700
         dev_xdp_install+0x592/0xd70
         dev_xdp_attach+0x355/0xf50
         dev_change_xdp_fd+0x176/0x210
         do_setlink.isra.0+0x220d/0x2b20
         rtnl_newlink+0x9f1/0x11b0

  -> #0 (&dev->lock){+.+.}-{4:4}:
         __mutex_lock+0x1ae/0x1f10
         netdev_put_lock+0x2d/0x1a0
         netdev_nl_queue_create_doit+0x801/0x1a70
         genl_family_rcv_msg_doit+0x206/0x300

   Possible unsafe locking scenario:

         CPU0                    CPU1
         ----                    ----
    lock(&netdev_virt_instance_lock_key);
                                 lock(&dev->lock);
                                 lock(&netdev_virt_instance_lock_key);
    lock(&dev->lock);

Let's narrow down the "virtual" class to only the devices which
can actually create a queue. More LoC and complexity, but that
is what we actually care about here. The rest needs to nest
under rtnl_lock, which bond does (famous last words?)

Take the instance locks in two passes, first the netkits then
the rest (matching the queue leasing order).
An alternative would be to make sure the close list is sorted
correctly from the start (queue head/tail appropriately in
unregister_netdevice_queue()). I think it works but feels
a little more fragile. Happy to change, tho.

netdev_can_create_queue() will now be used on paths where we
genuinely handle non-netkit, so we can't always set the extack.
Unfortunately, the (recently) added tracepoint in extack fires
even when extack is NULL.

Fixes: b6f74dff6d ("net: use two lockdep classes for the netdev instance lock")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://patch.msgid.link/20260929191543.3295633-1-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
History 2026-10-01 12:43:46 +02:00
arch llc: move the type 2 sockets out of tree 2026-10-01 10:07:32 +02:00
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 More features: 2026-09-30 14:19:25 -07:00
drivers net: axienet: add a MODULE_ALIAS for platform instantiation 2026-10-01 11:22:26 +02:00
fs 14 hotfixes. 10 are cc:stable. 11 are for MM. 2026-09-22 10:03:33 -07:00
include tcp: annotate lockless access to sk->sk_err 2026-10-01 11:06:29 +02:00
init Bootconfig fixes for v7.3-rc3 2026-09-13 09:16:36 -07:00
io_uring io_uring-7.3-20260911 2026-09-11 12:36:13 -07:00
ipc mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
kernel bpf-fixes 2026-09-24 08:25:26 -07:00
lib 14 hotfixes. 10 are cc:stable. 11 are for MM. 2026-09-14 08:59:09 -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 memblock: add missing HugeTLB flag name 2026-09-24 06:16:19 -07:00
net net: only give queue leasing devices a separate instance lock class 2026-10-01 12:43:46 +02:00
rust rust: net: netlink: Migrate to zerocopy's IntoBytes 2026-09-17 17:05:15 -07:00
samples rust: samples: add missing newlines in rust_print_main 2026-09-01 02:20:22 +02:00
scripts hid-for-linus-2026092202 2026-09-22 10:30:17 -07:00
security Landlock fix for v7.3-rc5 2026-09-24 10:53:59 -07:00
sound ASoC: Fixes for v7.3 2026-09-17 08:15:32 +02:00
tools selftests: drv-net: Request larger zcrx buffers 2026-09-30 17:16:05 -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 myself 2026-09-07 10:01:33 +02:00
.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 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-09-24 13:32:50 -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 w5100: detect carrier state using link status bit and optional interrupt 2026-09-29 17:31:21 -07:00
Makefile Linux 7.3-rc4 2026-09-20 13:48:15 -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