Subject: Re: [RFC v2 3/6] kthread: warn on kill signal if not OOM

From: James Bottomley <[email-masked]>
Date: Mon, 08 Sep 2014 22:38:29 -0700

On Tue, 2014-09-09 at 10:10 +0900, Tejun Heo wrote:
> Hello, Luis.
> 
> On Mon, Sep 08, 2014 at 06:04:23PM -0700, Luis R. Rodriguez wrote:
> > > I have no idea how the selection should be.  It could be per-insmod or
> > > maybe just a system-wide flag with explicit exceptions marked on
> > > drivers is good enough.  I don't know.
> > 
> > Its perfectly understandable if we don't know what path to take yet
> > and its also understandable for it to take time to figure out --
> > meanwhile though systemd already has merged a policy of a 30 second
> > timeout for *all drivers* though so we therefore need:
> 
> I'm not too convinced this is such a difficult problem to figure out.
> We already have most of logic in place and the only thing missing is
> how to switch it.  Wouldn't something like the following work?
> 
> * Add a sysctl knob to enable asynchronous device probing on module
>   load and enable asynchronous probing globally if the knob is set.
> 
> * Identify cases which can't be asynchronous and make them
>   synchronous.  e.g. keep who's doing request_module() and avoid
>   asynchronous probing if current is probing one of those.

What's wrong with just fixing systemd?  Arbitrary timeouts in init
scripts for system bring up are plain wrong ... I thought we had this
sorted out ten years ago when we were first having the arguments about
how long to wait for root; I'm surprised it's coming back again.

If we want to sort out some sync/async mechanism for probing devices, as
an agreement between the init systems and the kernel, that's fine, but
its a to-be negotiated enhancement.  For the current bug fix, just fix
the component that broke ... which would be systemd.

James