On Thu, Sep 24, 2020 at 8:47 AM Peter Xu <peterx@xxxxxxxxxx> wrote: > > On Wed, Sep 23, 2020 at 09:07:49AM -0700, Yang Shi wrote: > > For tmpfs map, the pmd split just clears the pmd entry without > > reinstalling ptes (oppositely anonymous map would reinstall ptes). It > > looks this patch intends to copy at pte level by splitting pmd. But > > I'm afraid this may not work for tmpfs mappings. > > IIUC that's exactly what we want. > > We only want to make sure the pinned tmpfs shared pages will be kept there in > the parent. It's not a must to copy the pages to the child, as long as they > can be faulted in later correctly. Aha, got your point. Yes, they can be refaulted in later. This is how the file THP pmd split was designed. > > -- > Peter Xu >
