On Tue, Oct 15, 2013 at 08:55:10PM +0200, Andrea Arcangeli wrote: > On Tue, Oct 15, 2013 at 10:53:10AM -0700, Hugh Dickins wrote: > > I'm afraid Andrea's mail about concurrent madvises gives me far more > > to think about than I have time for: seems to get into problems he > > knows a lot about but I'm unfamiliar with. If this patch looks good > > for now on its own, let's put it in; but no problem if you guys prefer > > to wait for a fuller solution of more problems, we can ride with this > > one internally for the moment. > > I'm very happy with the patch and I think it's a correct fix for the > COW scenario which is deterministic so the looping makes a meaningful > difference for it. If we wouldn't loop, part of the copied page > wouldn't be zapped after the COW. I like this patch, too. If we have the loop in __split_huge_page_pmd as suggested in this patch, can we assume that the pmd is stable after __split_huge_page_pmd returns? If it's true, we can remove pmd_none_or_trans_huge_or_clear_bad check in the callers side (zap_pmd_range and some other page table walking code.) Naoya Horiguchi -- 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>