Bug#761257: systemd: disrupts hugepages support

[Cyril Soldani]

On Fri, 12 Sep 2014 19:25:21 +0200
md at Linux.IT (Marco d'Itri) wrote:
> > 1) systemd *not* messing with the existing hugepages setup;
>
> This will not happen: it would be too much complex and anyway the new 
> "standard" location is /dev/hugepages/ .

It looks questionable to me, but you certainly know better (as I
don't know anything about it) and I won't argue any further.

> > 2) being warned when installing systemd-sysv that systemd handles
> >    hugepages differently (especially when I have hugepages entries
> >    in my fstab).
>
> But I think that we can add a preinst check, can you provide a simple 
> shell test case that checks for this condition?

I must first mention that the problem is less severe than initially
thought. As Ben Hutchings helped me discover (see #761299), you can
still use hugepages even when mounted several times. Our problem was
that the two mount points had different permissions, and our
applications were using the wrong one. It thus likely to affect less
users than initially thought.

If you are still willing to add a warning (which could still be nice,
IMO), a test like this might be sufficient:

    if 2>&1 grep -E '^[^#]*hugetlbfs' /etc/fstab >/dev/null; then
        echo "Hugepages entries found"
    fi

Regards,
-- 
"The nationalist not only does not disapprove of atrocities committed
 by his own side, he has a remarkable capacity for not even hearing
 about them."                                            George Orwell

Cyril Soldani <devmusings at legiasoft.com>