On Sat, 05 Jan 2013 20:59:57 -0600 Simon Jeons <simon.jeons@xxxxxxxxx> wrote: > (top-posting repaired) top-posting makes it really hard to reply to your email in a useful fashion. So if you want a reply, please don't top-post! > On Mon, 2012-12-17 at 19:00 +0100, Andrea Arcangeli wrote: > > Hi, > > > > I got a report for a minor regression introduced by commit > > 027ef6c87853b0a9df53175063028edb4950d476. > > > > So the problem is, pageattr creates kernel pagetables (pte and pmds) > > that breaks pte_present/pmd_present and the patch above exposed this > > invariant breakage for pmd_present. > > > > The same problem already existed for the pte and pte_present and it > > was fixed by commit 660a293ea9be709b893d371fbc0328fcca33c33a (if it > > wasn't for that commit, it wouldn't even be a regression). That fix > > avoids the pagefault to use pte_present. I could follow through by > > stopping using pmd_present/pmd_huge too. > > > > However I think it's more robust to fix pageattr and to clear the > > PSE/GLOBAL bitflags too in addition to the present bitflag. So the > > kernel page fault can keep using the regular > > pte_present/pmd_present/pmd_huge. > > > > The confusion arises because _PAGE_GLOBAL and _PAGE_PROTNONE are > > sharing the same bit, and in the pmd case we pretend _PAGE_PSE to be > > set only in present pmds (to facilitate split_huge_page final tlb > > flush). > > > > What's the status of these two patches? I expect they fell through the christmas cracks. I added them to my (getting large) queue of x86 patches for consideration by the x86 maintainers. Why do you ask? It seems the bug is a pretty minor one and that we need only fix it in 3.8 or even 3.9. Is that supposition incorrect? -- 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>