Re: [arch-projects] [PATCH 4/7] udev: exit on shutdown

On Wed, Oct 26, 2011 at 11:03:52PM -0500, Dan McGee wrote:
> On Wed, Oct 26, 2011 at 10:51 PM, Dave Reisner  wrote:
> > On Wed, Oct 26, 2011 at 07:12:13PM -0500, Dan McGee wrote:
> >> On Wed, Oct 26, 2011 at 6:38 PM, Tom Gundersen  wrote:
> >> > udev was receiving some events (due to e.g. swapoff) on shutdown
> >> > that caused it to fork new processes. These then receivde TERM before
> >> s/received/
> >> > they could finish, and complained on the console.
> >> >
> >> > In principle, I'm worried that, with the right ammonut of bad luck,
> >> s/amount/
> >> > we could fork off some process at exactly the wrong time which escapes
> >> > the killall logic.
> >> >
> >> > This, by the way, highlights the frailty of the killall stuff.
> >> Two quick thoughts here
> >> 1. Is there a need to even call swapoff? I can't believe it is
> >> essential for swap partitions. It unfortunately does makes sense for
> >> swap files so we can later unmount the file system they live on, but
> >> it looks like there is no way to differentiate. Dave, I know you want
> >> to submit a patch to util-linux for this... :)
> >
> > I'm such a tool. Preliminary patchwork for this now exists:
> >
> > http://code.falconindy.com/cgit/util-linux.git/log/?h=swapon
> >
> > If anyone wants to give it a once over from a user or developer
> > perspective, that'd be awesome.
> 
> Wow, you're awesome. I guess my first question would be- does it
> actually work? :) Just hotpatch the old initscripts to only swapoff
> file partitions and try shutting down and make sure it actually goes
> off without a hitch. This could definitely save some shutdown time on
> machines that have paged a non-trivial amount to swap.
> 
> -Dan

Of course it works!

It's far from useable, though. The swapon code is a mess and hasn't
really been touched in years. I'm going to track down Karel Zak at some
point and ask him if this is even something that's wanted and maybe get
some guidance as to what else should be cleaned up in the process.

d