Messages in this thread | | | Date | Tue, 15 Oct 2013 15:28:50 -0400 | From | Naoya Horiguchi <> | Subject | Re: mm: fix BUG in __split_huge_page_pmd |
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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
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