On Thu, Oct 25, 2012 at 05:44:31PM +0100, Will Deacon wrote: > On x86 memory accesses to pages without the ACCESSED flag set result in the > ACCESSED flag being set automatically. With the ARM architecture a page access > fault is raised instead (and it will continue to be raised until the ACCESSED > flag is set for the appropriate PTE/PMD). > > For normal memory pages, handle_pte_fault will call pte_mkyoung (effectively > setting the ACCESSED flag). For transparent huge pages, pmd_mkyoung will only > be called for a write fault. > > This patch ensures that faults on transparent hugepages which do not result > in a CoW update the access flags for the faulting pmd. > > Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx> > Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> > Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> > Signed-off-by: Will Deacon <will.deacon@xxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> > Ok chaps, I rebased this thing onto today's next (which basically > necessitated a rewrite) so I've reluctantly dropped my acks and kindly > ask if you could eyeball the new code, especially where the locking is > concerned. In the numa code (do_huge_pmd_prot_none), Peter checks again > that the page is not splitting, but I can't see why that is required. I don't either. If the thing was splitting when the fault happened, that path is not taken. And the locked pmd_same() check should rule out splitting setting in after testing pmd_trans_huge_splitting(). Peter? -- 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>