On Tue, 29 Sep 2015, Oleg Nesterov wrote:
> Cosmetic, but expand_upwards() and expand_downwards() overuse
> vma->vm_mm, a local variable makes sense imho.
>
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
> ---
> mm/mmap.c | 24 +++++++++++++-----------
> 1 file changed, 13 insertions(+), 11 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 4efdc37..7edf9ed 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -2148,6 +2148,7 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
> */
> int expand_upwards(struct vm_area_struct *vma, unsigned long address)
> {
> + struct mm_struct *mm = vma->vm_mm;
> int error;
>
> if (!(vma->vm_flags & VM_GROWSUP))
> @@ -2197,10 +2198,10 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
> * So, we reuse mm->page_table_lock to guard
> * against concurrent vma expansions.
> */
> - spin_lock(&vma->vm_mm->page_table_lock);
> + spin_lock(&mm->page_table_lock);
> if (vma->vm_flags & VM_LOCKED)
> - vma->vm_mm->locked_vm += grow;
> - vm_stat_account(vma->vm_mm, vma->vm_flags,
> + mm->locked_vm += grow;
> + vm_stat_account(mm, vma->vm_flags,
> vma->vm_file, grow);
> anon_vma_interval_tree_pre_update_vma(vma);
> vma->vm_end = address;
> @@ -2208,8 +2209,8 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
> if (vma->vm_next)
> vma_gap_update(vma->vm_next);
> else
> - vma->vm_mm->highest_vm_end = address;
> - spin_unlock(&vma->vm_mm->page_table_lock);
> + mm->highest_vm_end = address;
> + spin_unlock(&mm->page_table_lock);
>
> perf_event_mmap(vma);
> }
> @@ -2217,7 +2218,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
> }
> vma_unlock_anon_vma(vma);
> khugepaged_enter_vma_merge(vma, vma->vm_flags);
> - validate_mm(vma->vm_mm);
> + validate_mm(mm);
> return error;
> }
> #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
> @@ -2228,6 +2229,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
> int expand_downwards(struct vm_area_struct *vma,
> unsigned long address)
> {
> + struct mm_struct *mm = vma->vm_mm;
> int error;
>
> /*
> @@ -2272,17 +2274,17 @@ int expand_downwards(struct vm_area_struct *vma,
> * So, we reuse mm->page_table_lock to guard
> * against concurrent vma expansions.
> */
> - spin_lock(&vma->vm_mm->page_table_lock);
> + spin_lock(&mm->page_table_lock);
> if (vma->vm_flags & VM_LOCKED)
> - vma->vm_mm->locked_vm += grow;
> - vm_stat_account(vma->vm_mm, vma->vm_flags,
> + mm->locked_vm += grow;
> + vm_stat_account(mm, vma->vm_flags,
> vma->vm_file, grow);
> anon_vma_interval_tree_pre_update_vma(vma);
> vma->vm_start = address;
> vma->vm_pgoff -= grow;
> anon_vma_interval_tree_post_update_vma(vma);
> vma_gap_update(vma);
> - spin_unlock(&vma->vm_mm->page_table_lock);
> + spin_unlock(&mm->page_table_lock);
>
> perf_event_mmap(vma);
> }
> @@ -2290,7 +2292,7 @@ int expand_downwards(struct vm_area_struct *vma,
> }
> vma_unlock_anon_vma(vma);
> khugepaged_enter_vma_merge(vma, vma->vm_flags);
> - validate_mm(vma->vm_mm);
> + validate_mm(mm);
> return error;
> }
>
> --
> 2.4.3
>
>
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