Re: Kernel memory leak with x11/nvidia-driver

On Fri, Feb 05, 2016 at 09:05:00AM -0600, Eric van Gyzen wrote:
> On 02/ 4/16 08:05 PM, Mark Johnston wrote:
> > On Thu, Feb 04, 2016 at 05:37:24PM -0600, Eric van Gyzen wrote:
> >> On 02/ 3/16 10:54 AM, Eric van Gyzen wrote:
> >>> I just set up a new desktop running head with x11/nvidia-driver.  I've
> >>> discovered a memory leak where pages disappear from the queues, never to
> >>> return.  Specifically, the total of
> >>>       v_active_count
> >>>       v_inactive_count
> >>>       v_wire_count
> >>>       v_cache_count
> >>>       v_free_count
> >>> drops, eventually becoming /much/ less than v_page_count.  After leaving
> >>> xscreensaver running overnight, cycling the saver every 10 minutes, the
> >>> system was unusable, because it only had a few MB of memory.  (It has 8
> >>> GB physical.)
> >> In case anyone is curious, /usr/local/bin/xscreensaver-hacks/glmatrix
> >> triggers a fairly fast leak--around 600 pages per second.
> > I'm able to repro this on my workstation. With DTrace I can see that
> > glmatrix is allocating pages for an SG object at roughly the rate
> > they're being leaked. I took a look at r292373 (based on the history of
> > sg_pager.c) and noticed a vm_page_free() call was lost when
> > sg_pager_getpages() was simplified.
> >
> > The patch below seems to do the trick for me. Could you give it a try
> > and confirm that it fixes the problem? I run current+nvidia-driver on
> > multiple workstations but hadn't observed a leak until now, so maybe
> > there's something additional going on in your case. Then again, I just
> > use i3lock. :)
> >
> > diff --git a/sys/vm/sg_pager.c b/sys/vm/sg_pager.c
> > index 84bfa49..2cccb7ea 100644
> > --- a/sys/vm/sg_pager.c
> > +++ b/sys/vm/sg_pager.c
> > _at__at_ -189,6 +189,9 _at__at_ sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
> >   	VM_OBJECT_WLOCK(object);
> >   	TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q);
> >   	vm_page_replace_checked(page, object, offset, m[0]);
> > +	vm_page_lock(m[0]);
> > +	vm_page_free(m[0]);
> > +	vm_page_unlock(m[0]);
> >   	m[0] = page;
> >   	page->valid = VM_PAGE_BITS_ALL;
> >   
> 
> Your patch fixes the leak completely.  Nice work, Mark!
> 
> I didn't notice the leak until I unknowingly left the screensaver 
> cycling all overnight.  In my normal workflow, I open the windows I need 
> and pretty much leave them there.  This doesn't seem to trigger the 
> leak, at least not at a noticeable rate.
> 
> Thanks for your help!

Thank you. This was committed in r295330.