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    Subject[PATCH 02/13] mm/rmap: update to new mmu_notifier semantic v2
    Date
    From: Jérôme Glisse <jglisse@redhat.com>

    Replacing all mmu_notifier_invalidate_page() by mmu_notifier_invalidat_range()
    and making sure it is bracketed by call to mmu_notifier_invalidate_range_start/
    end.

    Note that because we can not presume the pmd value or pte value we have to
    assume the worse and unconditionaly report an invalidation as happening.

    Changed since v2:
    - try_to_unmap_one() only one call to mmu_notifier_invalidate_range()
    - compute end with PAGE_SIZE << compound_order(page)
    - fix PageHuge() case in try_to_unmap_one()

    Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
    Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Bernhard Held <berny156@gmx.de>
    Cc: Adam Borowski <kilobyte@angband.pl>
    Cc: Radim Krčmář <rkrcmar@redhat.com>
    Cc: Wanpeng Li <kernellwp@gmail.com>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Takashi Iwai <tiwai@suse.de>
    Cc: Nadav Amit <nadav.amit@gmail.com>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Cc: axie <axie@amd.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    ---
    mm/rmap.c | 35 ++++++++++++++++++++++++++++++++---
    1 file changed, 32 insertions(+), 3 deletions(-)

    diff --git a/mm/rmap.c b/mm/rmap.c
    index c8993c63eb25..c570f82e6827 100644
    --- a/mm/rmap.c
    +++ b/mm/rmap.c
    @@ -887,11 +887,21 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
    .address = address,
    .flags = PVMW_SYNC,
    };
    + unsigned long start = address, end;
    int *cleaned = arg;

    + /*
    + * We have to assume the worse case ie pmd for invalidation. Note that
    + * the page can not be free from this function.
    + */
    + end = min(vma->vm_end, start + (PAGE_SIZE << compound_order(page)));
    + mmu_notifier_invalidate_range_start(vma->vm_mm, start, end);
    +
    while (page_vma_mapped_walk(&pvmw)) {
    + unsigned long cstart, cend;
    int ret = 0;
    - address = pvmw.address;
    +
    + cstart = address = pvmw.address;
    if (pvmw.pte) {
    pte_t entry;
    pte_t *pte = pvmw.pte;
    @@ -904,6 +914,7 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
    entry = pte_wrprotect(entry);
    entry = pte_mkclean(entry);
    set_pte_at(vma->vm_mm, address, pte, entry);
    + cend = cstart + PAGE_SIZE;
    ret = 1;
    } else {
    #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
    @@ -918,6 +929,8 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
    entry = pmd_wrprotect(entry);
    entry = pmd_mkclean(entry);
    set_pmd_at(vma->vm_mm, address, pmd, entry);
    + cstart &= PMD_MASK;
    + cend = cstart + PMD_SIZE;
    ret = 1;
    #else
    /* unexpected pmd-mapped page? */
    @@ -926,11 +939,13 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
    }

    if (ret) {
    - mmu_notifier_invalidate_page(vma->vm_mm, address);
    + mmu_notifier_invalidate_range(vma->vm_mm, cstart, cend);
    (*cleaned)++;
    }
    }

    + mmu_notifier_invalidate_range_end(vma->vm_mm, start, end);
    +
    return true;
    }

    @@ -1324,6 +1339,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
    pte_t pteval;
    struct page *subpage;
    bool ret = true;
    + unsigned long start = address, end;
    enum ttu_flags flags = (enum ttu_flags)arg;

    /* munlock has nothing to gain from examining un-locked vmas */
    @@ -1335,6 +1351,14 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
    flags & TTU_MIGRATION, page);
    }

    + /*
    + * We have to assume the worse case ie pmd for invalidation. Note that
    + * the page can not be free in this function as call of try_to_unmap()
    + * must hold a reference on the page.
    + */
    + end = min(vma->vm_end, start + (PAGE_SIZE << compound_order(page)));
    + mmu_notifier_invalidate_range_start(vma->vm_mm, start, end);
    +
    while (page_vma_mapped_walk(&pvmw)) {
    /*
    * If the page is mlock()d, we cannot swap it out.
    @@ -1445,6 +1469,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
    if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
    WARN_ON_ONCE(1);
    ret = false;
    + /* We have to invalidate as we cleared the pte */
    page_vma_mapped_walk_done(&pvmw);
    break;
    }
    @@ -1490,8 +1515,12 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
    discard:
    page_remove_rmap(subpage, PageHuge(page));
    put_page(page);
    - mmu_notifier_invalidate_page(mm, address);
    + mmu_notifier_invalidate_range(mm, address,
    + address + PAGE_SIZE);
    }
    +
    + mmu_notifier_invalidate_range_end(vma->vm_mm, start, end);
    +
    return ret;
    }

    --
    2.13.5
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