Re: [PATCH v3 07/27] mm: Drop first_index/last_index in zap_details

Alistair Popple
2021-06-21T12:20:27Z

To me this looks like a good clean up that won't change any behaviour:

Reviewed-by: Alistair Popple <apopple@nvidia.com>

On Friday, 28 May 2021 6:21:26 AM AEST Peter Xu wrote:
> The first_index/last_index parameters in zap_details are actually only used in
> unmap_mapping_range_tree(). At the meantime, this function is only called by
> unmap_mapping_pages() once. Instead of passing these two variables through the
> whole stack of page zapping code, remove them from zap_details and let them
> simply be parameters of unmap_mapping_range_tree(), which is inlined.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> include/linux/mm.h | 2 --
> mm/memory.c | 20 ++++++++++----------
> 2 files changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index ef9ea6dfefff..db155be8e66c 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1726,8 +1726,6 @@ extern void user_shm_unlock(size_t, struct user_struct *);
> */
> struct zap_details {
> struct address_space *check_mapping; /* Check page->mapping if set */
> - pgoff_t first_index; /* Lowest page->index to unmap */
> - pgoff_t last_index; /* Highest page->index to unmap */
> };
>
> struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
> diff --git a/mm/memory.c b/mm/memory.c
> index 45a2f71e447a..27cf8a6375c6 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3305,20 +3305,20 @@ static void unmap_mapping_range_vma(struct vm_area_struct *vma,
> }
>
> static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
> + pgoff_t first_index,
> + pgoff_t last_index,
> struct zap_details *details)
> {
> struct vm_area_struct *vma;
> pgoff_t vba, vea, zba, zea;
>
> - vma_interval_tree_foreach(vma, root,
> - details->first_index, details->last_index) {
> -
> + vma_interval_tree_foreach(vma, root, first_index, last_index) {
> vba = vma->vm_pgoff;
> vea = vba + vma_pages(vma) - 1;
> - zba = details->first_index;
> + zba = first_index;
> if (zba < vba)
> zba = vba;
> - zea = details->last_index;
> + zea = last_index;
> if (zea > vea)
> zea = vea;
>
> @@ -3344,17 +3344,17 @@ static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
> void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
> pgoff_t nr, bool even_cows)
> {
> + pgoff_t first_index = start, last_index = start + nr - 1;
> struct zap_details details = { };
>
> details.check_mapping = even_cows ? NULL : mapping;
> - details.first_index = start;
> - details.last_index = start + nr - 1;
> - if (details.last_index < details.first_index)
> - details.last_index = ULONG_MAX;
> + if (last_index < first_index)
> + last_index = ULONG_MAX;
>
> i_mmap_lock_write(mapping);
> if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
> - unmap_mapping_range_tree(&mapping->i_mmap, &details);
> + unmap_mapping_range_tree(&mapping->i_mmap, first_index,
> + last_index, &details);
> i_mmap_unlock_write(mapping);
> }
>
>