On Fri, 10 Feb 2023 09:16:42 +0800 (CST)
<yang.yang29@xxxxxxxxxx> wrote:
> From: xu xin <xu.xin16@xxxxxxxxxx>
>
> A new function try_to_get_old_rmap_item is abstracted from
> get_next_rmap_item. This function will be reused by the subsequent
> patches about counting ksm_zero_pages.
>
> The patch improves the readability and reusability of KSM code.
>
> Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> Cc: Xuexin Jiang <jiang.xuexin@xxxxxxxxxx>
> Reviewed-by: Xiaokai Ran <ran.xiaokai@xxxxxxxxxx>
> Reviewed-by: Yang Yang <yang.yang29@xxxxxxxxxx>
>
> v5->v6:
> Modify some comments according to David's suggestions.
> ---
> mm/ksm.c | 27 +++++++++++++++++++++------
> 1 file changed, 21 insertions(+), 6 deletions(-)
>
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 83e2f74ae7da..905a79d213da 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -2214,23 +2214,38 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
> }
> }
>
> -static struct ksm_rmap_item *get_next_rmap_item(struct ksm_mm_slot *mm_slot,
> - struct ksm_rmap_item **rmap_list,
> - unsigned long addr)
> +static struct ksm_rmap_item *try_to_get_old_rmap_item(unsigned long addr,
> + struct ksm_rmap_item **rmap_list)
> {
> - struct ksm_rmap_item *rmap_item;
> -
> while (*rmap_list) {
> - rmap_item = *rmap_list;
> + struct ksm_rmap_item *rmap_item = *rmap_list;
why are you declaring this here? I think it's more clear if you
declare the variable at the beginning of the function, like it was
before
> +
> if ((rmap_item->address & PAGE_MASK) == addr)
> return rmap_item;
> if (rmap_item->address > addr)
> break;
> *rmap_list = rmap_item->rmap_list;
> + /*
> + * If we end up here, the VMA is MADV_UNMERGEABLE or its page
> + * is ineligible or discarded, e.g. MADV_DONTNEED.
> + */
> remove_rmap_item_from_tree(rmap_item);
> free_rmap_item(rmap_item);
> }
>
> + return NULL;
> +}
> +
> +static struct ksm_rmap_item *get_next_rmap_item(struct ksm_mm_slot *mm_slot,
> + struct ksm_rmap_item **rmap_list,
> + unsigned long addr)
> +{
> + struct ksm_rmap_item *rmap_item;
> +
> + rmap_item = try_to_get_old_rmap_item(addr, rmap_list);
> + if (rmap_item)
> + return rmap_item;
> +
> rmap_item = alloc_rmap_item();
> if (rmap_item) {
> /* It has already been zeroed */
