On Sat, Feb 16, 2019 at 1:11 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > On Sat, Feb 16, 2019 at 09:29:48AM -0800, Matthew Wilcox wrote: > > On Sat, Feb 16, 2019 at 07:35:11AM -0800, Matthew Wilcox wrote: > > > Another way to fix this would be to mask the address in dax_entry_mkclean(), > > > but I think this is cleaner. > > > > That's clearly rubbish, dax_entry_mkclean() can't possibly mask the > > address. It might be mis-aligned in another process. But ... if it's > > misaligned in another process, dax_entry_mkclean() will only clean the first > > PTE associated with the PMD; it won't clean the whole thing. I think we need > > something like this: > > Nope, this isn't enough. It's _necessary_ to find the processes that > have part of this PMD page mapped, but not the start of it. But it's > not _sufficient_ because it'll still only mkclean the first PTE. So we > need a loop. I'm feeling a bit over my head here. I may have a go at > a fuller fix, but if someone else wants to have a go at it, be my guest! Nothing comes to mind outside of pseudo-reverting this conversion by introducing a way to get back to the old semantics. If you don't see a path forward, us mere Xarray-mortals stand no chance.
