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Francesco Lavra db5b8cecbd pinctrl: mcp23s08: Disable all pin interrupts during probe
A chip being probed may have the interrupt-on-change feature enabled on
some of its pins, for example after a reboot. This can cause the chip to
generate interrupts for pins that don't have a registered nested handler,
which leads to a kernel crash such as below:

[    7.928897] Unable to handle kernel read from unreadable memory at virtual address 00000000000000ac
[    7.932314] Mem abort info:
[    7.935081]   ESR = 0x0000000096000004
[    7.938808]   EC = 0x25: DABT (current EL), IL = 32 bits
[    7.944094]   SET = 0, FnV = 0
[    7.947127]   EA = 0, S1PTW = 0
[    7.950247]   FSC = 0x04: level 0 translation fault
[    7.955101] Data abort info:
[    7.957961]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[    7.963421]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[    7.968447]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[    7.973734] user pgtable: 4k pages, 48-bit VAs, pgdp=00000000089b7000
[    7.980148] [00000000000000ac] pgd=0000000000000000, p4d=0000000000000000
[    7.986913] Internal error: Oops: 0000000096000004 [#1]  SMP
[    7.992545] Modules linked in:
[    8.073678] CPU: 0 UID: 0 PID: 81 Comm: irq/18-4-0025 Not tainted 7.0.0-rc6-gd2b5a1f931c8-dirty #199
[    8.073689] Hardware name: Khadas VIM3 (DT)
[    8.073692] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    8.094639] pc : _raw_spin_lock_irq+0x40/0x80
[    8.098970] lr : handle_nested_irq+0x2c/0x168
[    8.098979] sp : ffff800082b2bd20
[    8.106599] x29: ffff800082b2bd20 x28: ffff800080107920 x27: ffff800080104d88
[    8.106611] x26: ffff000003298080 x25: 0000000000000001 x24: 000000000000ff00
[    8.113707] x23: 0000000000000001 x22: 0000000000000000 x21: 000000000000000e
[    8.120850] x20: 0000000000000000 x19: 00000000000000ac x18: 0000000000000000
[    8.135046] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
[    8.135062] x14: ffff800081567ea8 x13: ffffffffffffffff x12: 0000000000000000
[    8.135070] x11: 00000000000000c0 x10: 0000000000000b60 x9 : ffff800080109e0c
[    8.135078] x8 : 1fffe0000069dbc1 x7 : 0000000000000001 x6 : ffff0000034ede00
[    8.135086] x5 : 0000000000000000 x4 : ffff0000034ede08 x3 : 0000000000000001
[    8.163460] x2 : 0000000000000000 x1 : 0000000000000001 x0 : 00000000000000ac
[    8.170560] Call trace:
[    8.180094]  _raw_spin_lock_irq+0x40/0x80 (P)
[    8.184443]  mcp23s08_irq+0x248/0x358
[    8.184462]  irq_thread_fn+0x34/0xb8
[    8.184470]  irq_thread+0x1a4/0x310
[    8.195093]  kthread+0x13c/0x150
[    8.198309]  ret_from_fork+0x10/0x20
[    8.201850] Code: d65f03c0 d2800002 52800023 f9800011 (885ffc01)
[    8.207931] ---[ end trace 0000000000000000 ]---

This issue has always been present, but has been latent until commit
"f9f4fda15e72" ("pinctrl: mcp23s08: init reg_defaults from HW at probe and
switch cache type"), which correctly removed reg_defaults from the regmap
and as a side effect changed the behavior of the interrupt handler so that
the real value of the MCP_GPINTEN register is now being read from the chip
instead of using a bogus 0 default value; a non-zero value for this
register can trigger the invocation of a nested handler which may not exist
(yet).
Fix this issue by disabling all pin interrupts during initialization.

Fixes: f9f4fda15e ("pinctrl: mcp23s08: init reg_defaults from HW at probe and switch cache type")
Signed-off-by: Francesco Lavra <flavra@baylibre.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>
2026-04-07 11:29:57 +02:00
arch s390: 2026-03-29 11:58:47 -07:00
block block-7.0-20260305 2026-03-06 08:36:18 -08:00
certs Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
crypto crypto: testmgr - Fix stale references to aes-generic 2026-03-03 11:57:15 -08:00
Documentation overlayfs fixes for 7.0-rc6 2026-03-29 09:34:50 -07:00
drivers pinctrl: mcp23s08: Disable all pin interrupts during probe 2026-04-07 11:29:57 +02:00
fs vfs-7.0-rc6.fixes 2026-03-29 15:24:28 -07:00
include vfs-7.0-rc6.fixes 2026-03-29 15:24:28 -07:00
init hardening fixes for v7.0-rc6 2026-03-25 14:47:18 -07:00
io_uring io_uring-7.0-20260327 2026-03-27 15:35:38 -07:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel Fix an argument order bug in the alarm timer forwarding logic, 2026-03-29 10:02:38 -07:00
lib bug: avoid format attribute warning for clang as well 2026-03-27 20:48:38 -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 Miscellaneous futex fixes: 2026-03-29 09:59:46 -07:00
net netfilter pull request 26-03-26 2026-03-26 15:38:14 +01:00
rust rust: regulator: do not assume that regulator_get() returns non-null 2026-03-24 13:08:21 +00:00
samples Landlock fix for v7.0-rc6 2026-03-26 12:03:37 -07:00
scripts hardening fixes for v7.0-rc6 2026-03-25 14:47:18 -07:00
security Landlock fix for v7.0-rc6 2026-03-26 12:03:37 -07:00
sound Revert "ALSA: hda/intel: Add MSI X870E Tomahawk to denylist" 2026-03-27 10:54:04 +01:00
tools vfs-7.0-rc6.fixes 2026-03-29 15:24:28 -07:00
usr kbuild: uapi: drop dependency on CC_CAN_LINK 2026-01-16 15:02:11 -07:00
virt KVM generic changes for 7.0 2026-03-11 18:01:55 +01:00
.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 MAINTAINERS, mailmap: update email address for Harry Yoo 2026-03-27 20:48:37 -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 MAINTAINERS: remove Thomas Falcon from IBM ibmvnic 2026-03-05 07:35:45 -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 i2c-for-7.0-rc6 2026-03-29 12:27:13 -07:00
Makefile Linux 7.0-rc6 2026-03-29 15:40:00 -07:00
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