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    Subject[PATCH 04/11] mm: page_vma_mapped_walk(): use pmde for *pvmw->pmd
    page_vma_mapped_walk() cleanup: re-evaluate pmde after taking lock, then
    use it in subsequent tests, instead of repeatedly dereferencing pointer.

    Signed-off-by: Hugh Dickins <hughd@google.com>
    Cc: <stable@vger.kernel.org>
    ---
    mm/page_vma_mapped.c | 11 ++++++-----
    1 file changed, 6 insertions(+), 5 deletions(-)

    diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
    index 973c3c4e72cc..81000dd0b5da 100644
    --- a/mm/page_vma_mapped.c
    +++ b/mm/page_vma_mapped.c
    @@ -194,18 +194,19 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)

    if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde)) {
    pvmw->ptl = pmd_lock(mm, pvmw->pmd);
    - if (likely(pmd_trans_huge(*pvmw->pmd))) {
    + pmde = *pvmw->pmd;
    + if (likely(pmd_trans_huge(pmde))) {
    if (pvmw->flags & PVMW_MIGRATION)
    return not_found(pvmw);
    - if (pmd_page(*pvmw->pmd) != page)
    + if (pmd_page(pmde) != page)
    return not_found(pvmw);
    return true;
    - } else if (!pmd_present(*pvmw->pmd)) {
    + } else if (!pmd_present(pmde)) {
    if (thp_migration_supported()) {
    if (!(pvmw->flags & PVMW_MIGRATION))
    return not_found(pvmw);
    - if (is_migration_entry(pmd_to_swp_entry(*pvmw->pmd))) {
    - swp_entry_t entry = pmd_to_swp_entry(*pvmw->pmd);
    + if (is_migration_entry(pmd_to_swp_entry(pmde))) {
    + swp_entry_t entry = pmd_to_swp_entry(pmde);

    if (migration_entry_to_page(entry) != page)
    return not_found(pvmw);
    --
    2.26.2
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