linux-kernel - Regression: system freeze on resume from suspend introduced by printk per-console suspended state

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Message-ID: <trinity-7f7239c9-c287-4c4e-a3cf-d1b0ad3d821a-1766356930635@3c-app-mailcom-bs11>
Date: Sun, 21 Dec 2025 23:42:10 +0100
From: ysard_git@....fr
To: linux-kernel@...r.kernel.org
Cc: john.ogness@...utronix.de, pmladek@...e.com, senozhatsky@...omium.org
Subject: Regression: system freeze on resume from suspend introduced by
 printk per-console suspended state

Hello,

I would like to report a suspend/resume regression which I bisected down
to a specific printk commit.

Summary
=======

On an ASUS laptop, resuming from suspend leads to a complete system freeze:
black screen, no keyboard response. The system must be powered off forcibly.

This regression is reproducible and was introduced by the following commit:

9e70a5e109a4a ("printk: Add per-console suspended state")

Hardware / environment
======================

- Laptop: G75VX ASUS
- CPU Arch: x86_64
- BIOS Information
    Version: G75VX.206
    Release Date: 02/27/2013
- GPU: NVIDIA GeForce GTX 670MX (standalone board only, no integrated chip, no optimus)
    Driver Version: 470.256.02
- Suspend mode: suspend-to-RAM (S3)
- Distribution: Debian Testing derivative (but the regression is reproduced with mainline kernel builds)
- Last working kernel from Debian:
    Linux version 6.5.0-5-amd64 (debian-kernel@...ts.debian.org)
    (gcc-13 (Debian 13.2.0-7) 13.2.0, GNU ld (GNU Binutils for Debian) 2.41)
    #1 SMP PREEMPT_DYNAMIC Debian 6.5.13-1 (2023-11-29)
- Kernel config: based on defconfig / Debian config
- Taint flag: yes, only Nvidia proprietary drivers are loaded and compiled via DKMS

Symptoms
========

- On resume from suspend to RAM
- Screen remains black
- No visible kernel panic (no logs)
- System is completely frozen (no VT switch, no Caps lock nor Num lock responses)
- Power cycle required

Regression details
==================

Suspend/resume works correctly with kernels prior to this commit.
After this commit, resume consistently results in a hard freeze.

I performed a git bisect on the upstream kernel repository. The result is:

9e70a5e109a4a23367810de09be826c52d27ee2f is the first bad commit

Commit details:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9e70a5e109a4a23367810de09be826c52d27ee2f

Reverting this commit on a later kernel (v6.7 0dd3ee31125508cd67f7e7172247f05b7fd1753a)
restores correct suspend/resume behavior on this machine.

The problem is still present on stable v6.18.2.

Additional notes
================

By playing around with the tests in /sys/power/, I can say that the problem only
occurs during a real S3 and not a simulated one.

No problem on resume:
$ echo core > /sys/power/pm_test
$ echo deep > /sys/power/mem_sleep
$ systemctl suspend

Freeze on resume:
$ echo none > /sys/power/pm_test
$ echo deep > /sys/power/mem_sleep
$ systemctl suspend

The issue appears hardware-dependent and may be related to the interaction
between printk console usability and resume ordering. The system likely
blocks silently during resume before the graphics stack becomes usable.

If additional debugging, logs, or testing are needed, I am available to
provide them.

Thank you for your time and for any guidance on how to proceed.

Best regards.