On Fri, Sep 15, 2017 at 09:01:00AM +0200, Michal Hocko wrote: > On Thu 14-09-17 15:00:11, jgli...@redhat.com wrote: > > From: Jérôme Glisse <jgli...@redhat.com> > > > > Fix for 4.14, zone device page always have an elevated refcount > > of one and thus page count sanity check in uncharge_page() is > > inappropriate for them. > > > > Signed-off-by: Jérôme Glisse <jgli...@redhat.com> > > Reported-by: Evgeny Baskakov <ebaska...@nvidia.com> > > Cc: Andrew Morton <a...@linux-foundation.org> > > Cc: Johannes Weiner <han...@cmpxchg.org> > > Cc: Michal Hocko <mho...@kernel.org> > > Cc: Vladimir Davydov <vdavydov....@gmail.com> > > Acked-by: Michal Hocko <mho...@suse.com> > > Side note. Wouldn't it be better to re-organize the check a bit? It is > true that this is VM_BUG so it is not usually compiled in but when it > preferably checks for unlikely cases first while the ref count will be > 0 in the prevailing cases. So can we have > VM_BUG_ON_PAGE(page_count(page) && !is_zone_device_page(page) && > !PageHWPoison(page), page); > > I would simply fold this nano optimization into the patch as you are > touching it already. Not sure it is worth a separate commit.
I am traveling sorry for late answer. This nano optimization make sense Andrew do you want me to respin or should we leave it be ? I don't mind either way. Cheers, Jérôme
