Hi Kefeng,
On Tue, May 28, 2024 at 9:45 PM Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> wrote:
>
> Add a #MC variant of folio_copy() which uses copy_mc_highpage() to
> support #MC handled during folio copy, it will be used in folio
> migration soon.
>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> ---
> include/linux/mm.h | 1 +
> mm/util.c | 20 ++++++++++++++++++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 12bf20ebae5a..0c78d67f787d 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1321,6 +1321,7 @@ void put_pages_list(struct list_head *pages);
>
> void split_page(struct page *page, unsigned int order);
> void folio_copy(struct folio *dst, struct folio *src);
> +int folio_mc_copy(struct folio *dst, struct folio *src);
>
> unsigned long nr_free_buffer_pages(void);
>
> diff --git a/mm/util.c b/mm/util.c
> index c9e519e6811f..9462dbf7ce02 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -828,6 +828,26 @@ void folio_copy(struct folio *dst, struct folio *src)
> }
> EXPORT_SYMBOL(folio_copy);
>
> +int folio_mc_copy(struct folio *dst, struct folio *src)
> +{
> + long nr = folio_nr_pages(src);
> + long i = 0;
> + int ret = 0;
> +
> + for (;;) {
> + if (copy_mc_highpage(folio_page(dst, i), folio_page(src, i))) {
> + ret = -EFAULT;
> + break;
> + }
> + if (++i == nr)
> + break;
> + cond_resched();
> + }
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(folio_mc_copy);
The code below might be clearer:
+int folio_mc_copy(struct folio *dst, struct folio *src)
+{
+ long nr = folio_nr_pages(src);
+ long i = 0;
+
+ for (;;) {
+ if (copy_mc_highpage(folio_page(dst, i), folio_page(src, i)))
+ return -EFAULT;
+ if (++i == nr)
+ break;
+ cond_resched();
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL(folio_mc_copy);
IMO, we can return the error code directly without needing to use the 'ret'.
Thanks,
Lance
> +
> int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
> int sysctl_overcommit_ratio __read_mostly = 50;
> unsigned long sysctl_overcommit_kbytes __read_mostly;
> --
> 2.27.0
>
>
