On 09/25/2015 11:20 PM, Ingo Molnar wrote: > * Dave Hansen <[email protected]> wrote: ... >> Since follow_pte() fails for all huge >> pages, it just falls back to pulling the protection key out of the VMA, >> which _does_ work for huge pages. > > That might be true for explicit hugetlb vmas, but what about transparent > hugepages > that can show up in regular vmas?
All PTEs (large or small) established under a given VMA have the same protection key. Any change in protection key for a range will either change or split the VMA. So I think it's safe to rely on the VMA entirely. Well, as least as safe as the PTE. It's definitely a wee bit racy, which I'll elaborate on when I repost the patches. >> I've actually removed the PTE walking and I just now use the VMA directly. >> I >> don't see a ton of additional value from walking the page tables when we can >> get >> what we need from the VMA. > > That's actually good, because it's also cheap, especially if we can get rid > of the > extra find_vma(). > > and we (thankfully) have no non-linear vmas to worry about anymore. Yep. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
