Re: [PATCH 0/1] printk: Yield console_sem to blocking waiters

[Aruna Ramakrishna <aruna.ramakrishna@oracle.com>]

> On Sep 11, 2026, at 1:08 AM, John Ogness <john.ogness@linutronix.de> wrote:
> 
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> On 2026-09-10, Aruna Ramakrishna <aruna.ramakrishna@oracle.com> wrote:
> > Problem context:
> >
> > After a reboot, NetworkManager failed to bring up interfaces because
> > systemd was stalled, due to a flood of printk warnings.
> 
> Note that kernel warnings are considered serious and will put the CPU
> into emergency state.

I apologize - I misspoke. These were not KERN_WARNs, rather KERN_INFOs
being used by RDS to warn of connection failures etc. A flood of these caused
the console_lock starvation.

> 
> > Systemd was
> > blocked waiting on the console lock for over 122 seconds:
> 
> Also note that the console lock is related to legacy consoles. Rather
> than trying to make the legacy console trainwreck more reliable and
> non-interfering, efforts should be spent converting legacy consoles to
> NBCON.
> 
> What console driver are you using?
> 
> For v7.3 the 8250 driver will be NBCON.
> 
> John
> 

This is for the legacy 8250 serial console.

Thanks,
Aruna