On Mon, May 12, 2014 at 04:24:07PM -0400, Naoya Horiguchi wrote:
> (Cced: Andrew)
>
> On Sat, May 10, 2014 at 11:14:34AM +0800, Chen Yucong wrote:
> > For handling a free hugepage in memory failure, the race will happen if
> > another thread hwpoisoned this hugepage concurrently. So we need to
> > check PageHWPoison instead of !PageHWPoison.
> >
> > If hwpoison_filter(p) returns true or a race happens, then we need to
> > unlock_page(hpage).
> >
> > Signed-off-by: Chen Yucong <slaoub@xxxxxxxxx>
> > Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
>
> I tested this patch on latest linux-next, and confirmed that memory error
> on a tail page of a free hugepage is properly handled.
Patch looks good to me too.
Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
-Andi
>
> Tested-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
>
> And I think this patch should go into all recent stable trees, since this
> bug exists since 2.6.36 (because of my patch, sorry.)
>
> > ---
> > mm/memory-failure.c | 15 ++++++++-------
> > 1 file changed, 8 insertions(+), 7 deletions(-)
> >
> > diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> > index 35ef28a..dbf8922 100644
> > --- a/mm/memory-failure.c
> > +++ b/mm/memory-failure.c
> > @@ -1081,15 +1081,16 @@ int memory_failure(unsigned long pfn, int
> > trapno, int flags)
>
> This linebreak breaks patch format. I guess it's done by your email
> client or copy and paste. If it's true, git-send-email might be helpful
> to avoid such errors.
>
> Thanks,
> Naoya
>
>
> > return 0;
> > } else if (PageHuge(hpage)) {
> > /*
> > - * Check "just unpoisoned", "filter hit", and
> > - * "race with other subpage."
> > + * Check "filter hit" and "race with other subpage."
> > */
> > lock_page(hpage);
> > - if (!PageHWPoison(hpage)
> > - || (hwpoison_filter(p) && TestClearPageHWPoison(p))
> > - || (p != hpage && TestSetPageHWPoison(hpage))) {
> > - atomic_long_sub(nr_pages, &num_poisoned_pages);
> > - return 0;
> > + if (PageHWPoison(hpage)) {
> > + if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
> > + || (p != hpage && TestSetPageHWPoison(hpage))) {
> > + atomic_long_sub(nr_pages, &num_poisoned_pages);
> > + unlock_page(hpage);
> > + return 0;
> > + }
> > }
> > set_page_hwpoison_huge_page(hpage);
> > res = dequeue_hwpoisoned_huge_page(hpage);
> > --
> > 1.7.10.4
> >
> >
> >
> >
> >
> >
> > --
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> >
--
ak@xxxxxxxxxxxxxxx -- Speaking for myself only
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