Rahul Bukte 0162ab3220 drm/i915/gt: Check set_default_submission() before deferencing
When the i915 driver firmware binaries are not present, the
set_default_submission pointer is not set. This pointer is
dereferenced during suspend anyways.

Add a check to make sure it is set before dereferencing.

[   23.289926] PM: suspend entry (deep)
[   23.293558] Filesystems sync: 0.000 seconds
[   23.298010] Freezing user space processes
[   23.302771] Freezing user space processes completed (elapsed 0.000 seconds)
[   23.309766] OOM killer disabled.
[   23.313027] Freezing remaining freezable tasks
[   23.318540] Freezing remaining freezable tasks completed (elapsed 0.001 seconds)
[   23.342038] serial 00:05: disabled
[   23.345719] serial 00:02: disabled
[   23.349342] serial 00:01: disabled
[   23.353782] sd 0:0:0:0: [sda] Synchronizing SCSI cache
[   23.358993] sd 1:0:0:0: [sdb] Synchronizing SCSI cache
[   23.361635] ata1.00: Entering standby power mode
[   23.368863] ata2.00: Entering standby power mode
[   23.445187] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   23.452194] #PF: supervisor instruction fetch in kernel mode
[   23.457896] #PF: error_code(0x0010) - not-present page
[   23.463065] PGD 0 P4D 0
[   23.465640] Oops: Oops: 0010 [#1] SMP NOPTI
[   23.469869] CPU: 8 UID: 0 PID: 211 Comm: kworker/u48:18 Tainted: G S      W           6.19.0-rc4-00020-gf0b9d8eb98df #10 PREEMPT(voluntary)
[   23.482512] Tainted: [S]=CPU_OUT_OF_SPEC, [W]=WARN
[   23.496511] Workqueue: async async_run_entry_fn
[   23.501087] RIP: 0010:0x0
[   23.503755] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[   23.510324] RSP: 0018:ffffb4a60065fca8 EFLAGS: 00010246
[   23.515592] RAX: 0000000000000000 RBX: ffff9f428290e000 RCX: 000000000000000f
[   23.522765] RDX: 0000000000000000 RSI: 0000000000000282 RDI: ffff9f428290e000
[   23.529937] RBP: ffff9f4282907070 R08: ffff9f4281130428 R09: 00000000ffffffff
[   23.537111] R10: 0000000000000000 R11: 0000000000000001 R12: ffff9f42829070f8
[   23.544284] R13: ffff9f4282906028 R14: ffff9f4282900000 R15: ffff9f4282906b68
[   23.551457] FS:  0000000000000000(0000) GS:ffff9f466b2cf000(0000) knlGS:0000000000000000
[   23.559588] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   23.565365] CR2: ffffffffffffffd6 CR3: 000000031c230001 CR4: 0000000000f70ef0
[   23.572539] PKRU: 55555554
[   23.575281] Call Trace:
[   23.577770]  <TASK>
[   23.579905]  intel_engines_reset_default_submission+0x42/0x60
[   23.585695]  __intel_gt_unset_wedged+0x191/0x200
[   23.590360]  intel_gt_unset_wedged+0x20/0x40
[   23.594675]  gt_sanitize+0x15e/0x170
[   23.598290]  i915_gem_suspend_late+0x6b/0x180
[   23.602692]  i915_drm_suspend_late+0x35/0xf0
[   23.607008]  ? __pfx_pci_pm_suspend_late+0x10/0x10
[   23.611843]  dpm_run_callback+0x78/0x1c0
[   23.615817]  device_suspend_late+0xde/0x2e0
[   23.620037]  async_suspend_late+0x18/0x30
[   23.624082]  async_run_entry_fn+0x25/0xa0
[   23.628129]  process_one_work+0x15b/0x380
[   23.632182]  worker_thread+0x2a5/0x3c0
[   23.635973]  ? __pfx_worker_thread+0x10/0x10
[   23.640279]  kthread+0xf6/0x1f0
[   23.643464]  ? __pfx_kthread+0x10/0x10
[   23.647263]  ? __pfx_kthread+0x10/0x10
[   23.651045]  ret_from_fork+0x131/0x190
[   23.654837]  ? __pfx_kthread+0x10/0x10
[   23.658634]  ret_from_fork_asm+0x1a/0x30
[   23.662597]  </TASK>
[   23.664826] Modules linked in:
[   23.667914] CR2: 0000000000000000
[   23.671271] ------------[ cut here ]------------

Signed-off-by: Rahul Bukte <rahul.bukte@sony.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/20260203044839.1555147-1-suraj.kandpal@intel.com
(cherry picked from commit daa199abc3d3d1740c9e3a2c3e9216ae5b447cad)
Fixes: ff44ad51eb ("drm/i915: Move engine->submit_request selection to a vfunc")
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
2026-03-18 11:53:20 +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
2026-03-15 13:52:05 -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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