swapping is completely broken in -CURRENT r334649?

[Mark Johnston]

On Fri, Jun 15, 2018 at 11:07:34AM +0200, Kurt Jaeger wrote:
> Hi!
> 
> > > > The change was committed as r334752.  Are you seeing unexpected OOM
> > > > kills on or after that revision?
> > > 
> > > When I tried to run a qemu-based poudriere run yesterday on a r334918
> > > box, it killed a few processes outside of that run and did not
> > > work out.
> > > 
> > > I'm unsure it was because of that problem or a problem with qemu.
> > 
> > How much memory and swap does the guest have?
> 
> It's started by poudriere, I do not really know.
> 
> > Were you consistently able to complete a run before?
> 
> Two years ago, on a much lower version of FreeBSD, yes.
> 
> I just started it again, and after a while the qemu-ppc64-static
> was at approx. 23 GB memory and increasing, without much progress.

I suspect it is a different issue then.

> > If it's happening during a poudriere run, it may well have been a true
> > OOM situation.  The patch below prints a few stats to the dmesg before
> > the kill.  The output of that together with "sysctl vm" output should be
> > enough to determine what's happening.
> > 
> > diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c
> > index 264c98203c51..9c7ebcf451ec 100644
> > --- a/sys/vm/vm_pageout.c
> > +++ b/sys/vm/vm_pageout.c
> > @@ -1670,6 +1670,8 @@ vm_pageout_mightbe_oom(struct vm_domain *vmd, int page_shortage,
> >  	 * start OOM.  Initiate the selection and signaling of the
> >  	 * victim.
> >  	 */
> > +	printf("v_free_count: %u, v_inactive_count: %u\n",
> > +	    vmd->vmd_free_count, vmd->vmd_pagequeues[PQ_INACTIVE].pq_cnt);
> >  	vm_pageout_oom(VM_OOM_MEM);
> >  
> >  	/*
> 
> I'll have a look at this.
> 
> -- 
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