Messages in this thread | | | Date | Wed, 03 Apr 2013 16:01:53 -0400 | From | Rik van Riel <> | Subject | Re: [PATCH v3 3/3] hugetlbfs: add swap entry check in follow_hugetlb_page() |
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On 04/03/2013 02:35 PM, Naoya Horiguchi wrote: > With applying the previous patch "hugetlbfs: stop setting VM_DONTDUMP in > initializing vma(VM_HUGETLB)" to reenable hugepage coredump, if a memory > error happens on a hugepage and the affected processes try to access > the error hugepage, we hit VM_BUG_ON(atomic_read(&page->_count) <= 0) > in get_page(). > > The reason for this bug is that coredump-related code doesn't recognise > "hugepage hwpoison entry" with which a pmd entry is replaced when a memory > error occurs on a hugepage. > In other words, physical address information is stored in different bit layout > between hugepage hwpoison entry and pmd entry, so follow_hugetlb_page() > which is called in get_dump_page() returns a wrong page from a given address. > > We need to filter out only hwpoison hugepages to have data on healthy > hugepages in coredump. So this patch makes follow_hugetlb_page() avoid > trying to get page when a pmd is in swap entry like format. > > ChangeLog v3: > - add comment about using is_swap_pte() > > Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Reviewed-by: Michal Hocko <mhocko@suse.cz> > Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org> > Cc: stable@vger.kernel.org
Reviewed-by: Rik van Riel <riel@redhat.com>
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