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    SubjectRe: hugepage related lockdep trace.
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    Hillf Danton <dhillf@gmail.com> writes:

    > On Fri, Jul 19, 2013 at 1:42 AM, Aneesh Kumar K.V
    > <aneesh.kumar@linux.vnet.ibm.com> wrote:
    >> Minchan Kim <minchan@kernel.org> writes:
    >>> IMHO, it's a false positive because i_mmap_mutex was held by kswapd
    >>> while one in the middle of fault path could be never on kswapd context.
    >>>
    >>> It seems lockdep for reclaim-over-fs isn't enough smart to identify
    >>> between background and direct reclaim.
    >>>
    >>> Wait for other's opinion.
    >>
    >> Is that reasoning correct ?. We may not deadlock because hugetlb pages
    >> cannot be reclaimed. So the fault path in hugetlb won't end up
    >> reclaiming pages from same inode. But the report is correct right ?
    >>
    >>
    >> Looking at the hugetlb code we have in huge_pmd_share
    >>
    >> out:
    >> pte = (pte_t *)pmd_alloc(mm, pud, addr);
    >> mutex_unlock(&mapping->i_mmap_mutex);
    >> return pte;
    >>
    >> I guess we should move that pmd_alloc outside i_mmap_mutex. Otherwise
    >> that pmd_alloc can result in a reclaim which can call shrink_page_list ?
    >>
    > Hm, can huge pages be reclaimed, say by kswapd currently?

    No we don't reclaim hugetlb pages.

    -aneesh



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