On Fri, Sep 15, 2017 at 09:01:00AM +0200, Michal Hocko wrote: > On Thu 14-09-17 15:00:11, [email protected] wrote: > > From: Jérôme Glisse <[email protected]> > > > > 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 <[email protected]> > > Reported-by: Evgeny Baskakov <[email protected]> > > Cc: Andrew Morton <[email protected]> > > Cc: Johannes Weiner <[email protected]> > > Cc: Michal Hocko <[email protected]> > > Cc: Vladimir Davydov <[email protected]> > > Acked-by: Michal Hocko <[email protected]> > > 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
