On Thu, Dec 16, 2021 at 06:45:07PM +1100, Alistair Popple wrote: > On Thursday, 16 December 2021 6:06:54 PM AEDT Peter Xu wrote: > > [...] > > > I wondered how it could have worked - I thought e.g. pte_alloc_one() will > > always return a pgtable page will all zero-filled, whose allocation should > > require __GFP_ZERO anyway. But then I quickly noticed that pte_alloc_one() is > > per-arch too.. That explains, because per-arch can re-initialize the default > > pte values. > > Yes, I have wondered the same things before as well. It's all a little bit of > fun some of this stuff. > > > I thought this patch can greatly simplify things but I overlooked the > > pte_none() check you mentioned. So it seems I have no good choice but add that > > flag back. > > > > There's another alternative is we do pte_clear() on vmf->orig_pte as the new > > way to initialize it. I believe it should work too for s390 and xtensa. > > > > Any preference? > > I prefer the later approach (initialising to pte_clear) as it seems cleaner, > and pte_none(pte_clear()) is true for every architecture afaik. Will do. -- Peter Xu
