Re: [RFC][PATCHv6 00/12] printk: introduce printing kernel thread

Steven Rostedt
2018-01-09T22:47:54Z

On Tue, 9 Jan 2018 14:17:05 -0800
Tejun Heo <tj@kernel.org> wrote:

> Hello, Steven.
>
> On Tue, Jan 09, 2018 at 05:08:47PM -0500, Steven Rostedt wrote:
> > The scenario you listed would affect multiple CPUs and multiple CPUs
> > would be flooding printk. In that case my patch WILL help. Because the
> > current method, the first CPU to do the printk will get stuck doing the
> > printk for ALL OTHER CPUs. With my patch, the printk load will migrate
> > around and there will not be a single CPU that is stuck.
>
> Maybe it can break out eventually but that can take a really long
> time. It's OOM. Most of userland is waiting for reclaim. There
> isn't all that much going on outside that and there can only be one
> CPU which is OOMing. The kernel isn't gonna be all that chatty.

Are you saying that the OOM is stuck printing over and over on a single
CPU. Perhaps we should fix THAT.

-- Steve