On 03/02/2017 04:10 PM, Kirill A. Shutemov wrote:
> Restructure code in preparation for a fix.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> mm/huge_memory.c | 52 ++++++++++++++++++++++++++--------------------------
> 1 file changed, 26 insertions(+), 26 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 71e3dede95b4..e7ce73b2b208 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1722,37 +1722,37 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
> {
> struct mm_struct *mm = vma->vm_mm;
> spinlock_t *ptl;
> - int ret = 0;
> + pmd_t entry;
> + bool preserve_write;
> + int ret;
>
> ptl = __pmd_trans_huge_lock(pmd, vma);
> - if (ptl) {
> - pmd_t entry;
> - bool preserve_write = prot_numa && pmd_write(*pmd);
> - ret = 1;
> + if (!ptl)
> + return 0;
>
> - /*
> - * Avoid trapping faults against the zero page. The read-only
> - * data is likely to be read-cached on the local CPU and
> - * local/remote hits to the zero page are not interesting.
> - */
> - if (prot_numa && is_huge_zero_pmd(*pmd)) {
> - spin_unlock(ptl);
> - return ret;
> - }
> + preserve_write = prot_numa && pmd_write(*pmd);
> + ret = 1;
>
> - if (!prot_numa || !pmd_protnone(*pmd)) {
> - entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd);
> - entry = pmd_modify(entry, newprot);
> - if (preserve_write)
> - entry = pmd_mk_savedwrite(entry);
> - ret = HPAGE_PMD_NR;
> - set_pmd_at(mm, addr, pmd, entry);
> - BUG_ON(vma_is_anonymous(vma) && !preserve_write &&
> - pmd_write(entry));
> - }
> - spin_unlock(ptl);
> - }
> + /*
> + * Avoid trapping faults against the zero page. The read-only
> + * data is likely to be read-cached on the local CPU and
> + * local/remote hits to the zero page are not interesting.
> + */
> + if (prot_numa && is_huge_zero_pmd(*pmd))
> + goto unlock;
>
> + if (prot_numa && pmd_protnone(*pmd))
> + goto unlock;
> +
> + entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd);
> + entry = pmd_modify(entry, newprot);
> + if (preserve_write)
> + entry = pmd_mk_savedwrite(entry);
> + ret = HPAGE_PMD_NR;
> + set_pmd_at(mm, addr, pmd, entry);
> + BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
> +unlock:
> + spin_unlock(ptl);
> return ret;
> }
>
>
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