On Thu 2025-11-13 17:09:48, John Ogness wrote:
Allowing irq_work to be scheduled while trying to suspend has shown to cause problems as some architectures interpret the pending interrupts as a reason to not suspend. This became a problem for printk() with the introduction of NBCON consoles. With every printk() call, NBCON console printing kthreads are woken by queueing irq_work. This means that irq_work continues to be queued due to printk() calls late in the suspend procedure.
Avoid this problem by preventing printk() from queueing irq_work once console suspending has begun. This applies to triggering NBCON and legacy deferred printing as well as klogd waiters.
Since triggering of NBCON threaded printing relies on irq_work, the pr_flush() within console_suspend_all() is used to perform the final flushing before suspending consoles and blocking irq_work queueing. NBCON consoles that are not suspended (due to the usage of the "no_console_suspend" boot argument) transition to atomic flushing.
Introduce a new global variable @console_irqwork_blocked to flag when irq_work queueing is to be avoided. The flag is used by printk_get_console_flush_type() to avoid allowing deferred printing and switch NBCON consoles to atomic flushing. It is also used by vprintk_emit() to avoid klogd waking.
Add WARN_ON_ONCE(console_irqwork_blocked) to the irq_work queuing functions to catch any code that attempts to queue printk irq_work during the suspending/resuming procedure.
Cc: stable@vger.kernel.org # 6.13.x because no drivers in 6.12.x Fixes: 6b93bb41f6ea ("printk: Add non-BKL (nbcon) console basic infrastructure") Closes: https://lore.kernel.org/lkml/DB9PR04MB8429E7DDF2D93C2695DE401D92C4A@DB9PR04M... Signed-off-by: John Ogness john.ogness@linutronix.de
The changes look goot to me:
Reviewed-by: Petr Mladek pmladek@suse.com
Best Regards, Petr