On Fri, Apr 17, 2020 at 10:26:18PM +0800, chenqiwu wrote: > On Fri, Apr 17, 2020 at 01:43:12PM +0200, Michal Hocko wrote: > > On Fri 17-04-20 18:31:54, qiwuchen55@xxxxxxxxx wrote: > > > From: chenqiwu <chenqiwu@xxxxxxxxxx> > > > > > > If we get a special mapping page like device mapping page or zero page > > > when copy_one_pte, it's necessary add the page refcount count. > > > > From the changelog it is not clear what is the actual problem and how > > the patch address it. Please be more verbose. > > > I don't find any actual problem, but I think there should be addressed > to update the page refcount for special mappings include devmap and zero > page instead of doing nothing else, since we copy the pte from one task > to the other. But the zero page is special. It's never freed. So unless we're seeing a refcount problem with the zero page, I would suggest that your patch is eventually going to overflow the refcount on the zero page.
