On Thu, Oct 31, 2019 at 08:01:25AM -0000, Stuart Henderson wrote:
> On 2019-10-30, Jurjen Oskam <jur...@osk.am> wrote:
> >
> > All snapshots I tried up to and including this point did not show the
> > problem:
> > OpenBSD 6.6-beta (GENERIC.MP) #202: Mon Aug 12 11:01:21 MDT 2019
> >
> > All snapshots I tried starting from this point show the problem:
> > OpenBSD 6.6-beta (GENERIC.MP) #207: Tue Aug 13 11:32:34 MDT 2019
> >
> >
> > Would it be helpful to start a binary search for the exact commit that
> > introduced the problem?
>
> Yes, definitely! We usually do this with date-based cvs updates.
>
> > I've been looking at the commit history around
> > that time but haven't been able to spot an obvious candidate; but that's
> > probably because I'm not a programmer.
>
> Sometimes diffs are tested in snapshots before they're committed,
> so you might need to look beyond the snapshot dates to find the
> commit.
This took a while. I was not able to isolate a commit, but I did find
the variable that can reliably trigger the problem.
It's a bit embarrasing to say that the trigger is a f*ckup at my end: in my
template configuration for short-lived VMs, I accidentally configured /usr
to be 1G. I'm aware this is too small, but I never noticed because it
didn't seem to cause any problem for quite a few releases. I guess at
some point the kernel grew a bit and then the problem started to occur
during reorder_kernel.
After configuring /usr to be created at 4G (and leaving everything else the
same), the problem never occurred again.
This does lead me to a question though. Is it expected that a (nearly) full
filesystem can result in dmesg error messages such as these? (None of the
filesystems on the system are mounted softdep)
uvn_flush: obj=0xfffffd813ee78298, offset=0x33f0000. error during pageout.
uvn_flush: WARNING: changes to page may be lost!
uvn_flush: obj=0x0, offset=0x33f0000. error during pageout.
uvn_flush: WARNING: changes to page may be lost!
[ repeat last two lines many times ]
uvn_flush: obj=0xfffffd813ee78298, offset=0x3400000. error during pageout.
uvn_flush: WARNING: changes to page may be lost!
uvn_flush: obj=0x0, offset=0x3400000. error during pageout.
uvn_flush: WARNING: changes to page may be lost!
[ repeat last two lines many times ]
/dev/sd0a on / type ffs (local)
/dev/sd0i on /home type ffs (local, nodev, nosuid)
/dev/sd0d on /tmp type ffs (local, nodev, nosuid)
/dev/sd0f on /usr type ffs (local, nodev)
/dev/sd0g on /usr/X11R6 type ffs (local, nodev)
/dev/sd0h on /usr/local type ffs (local, nodev, wxallowed)
/dev/sd0e on /var type ffs (local, nodev, nosuid)
Regards,
Jurjen Oskam
