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    Subject[PATCH 23/64] mm: huge pagecache: do not check mmap_sem state
    Date
    From: Davidlohr Bueso <dave@stgolabs.net>

    *THIS IS A HACK*

    By dropping the rwsem_is_locked checks in zap_pmd_range()
    and zap_pud_range() we can avoid having to teach
    file_operations about mmrange. For example in xfs:
    iomap_dio_rw() is called by .read_iter file callbacks.

    No-Yet-Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
    ---
    mm/memory.c | 3 ---
    1 file changed, 3 deletions(-)

    diff --git a/mm/memory.c b/mm/memory.c
    index 7c69674cd9da..598a8c69e3d3 100644
    --- a/mm/memory.c
    +++ b/mm/memory.c
    @@ -1422,8 +1422,6 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
    next = pmd_addr_end(addr, end);
    if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
    if (next - addr != HPAGE_PMD_SIZE) {
    - VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
    - !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
    __split_huge_pmd(vma, pmd, addr, false, NULL);
    } else if (zap_huge_pmd(tlb, vma, pmd, addr))
    goto next;
    @@ -1459,7 +1457,6 @@ static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
    next = pud_addr_end(addr, end);
    if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
    if (next - addr != HPAGE_PUD_SIZE) {
    - VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
    split_huge_pud(vma, pud, addr);
    } else if (zap_huge_pud(tlb, vma, pud, addr))
    goto next;
    --
    2.13.6
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