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
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
@@ -189,6 +189,9 @@ sg_pager_getpages(vm_object_t object, vm_page_t *m, int 
count, int *rbehind,
        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!

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