On 09/25/2015 11:20 PM, Ingo Molnar wrote: > * Dave Hansen <dave@xxxxxxxx> 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>