On Tue, May 24, 2022 at 02:05:44PM +0800, Muchun Song wrote:
> In the later patch, we will reparent the LRU pages. The pages moved to
> appropriate LRU list can be reparented during the process of the
> move_pages_to_lru(). So holding a lruvec lock by the caller is wrong, we
> should use the more general interface of folio_lruvec_relock_irq() to
> acquire the correct lruvec lock.
>
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> ---
> mm/vmscan.c | 49 +++++++++++++++++++++++++------------------------
> 1 file changed, 25 insertions(+), 24 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 1678802e03e7..761d5e0dd78d 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2230,23 +2230,28 @@ static int too_many_isolated(struct pglist_data *pgdat, int file,
> * move_pages_to_lru() moves pages from private @list to appropriate LRU list.
> * On return, @list is reused as a list of pages to be freed by the caller.
> *
> - * Returns the number of pages moved to the given lruvec.
> + * Returns the number of pages moved to the appropriate LRU list.
> + *
> + * Note: The caller must not hold any lruvec lock.
> */
> -static unsigned int move_pages_to_lru(struct lruvec *lruvec,
> - struct list_head *list)
> +static unsigned int move_pages_to_lru(struct list_head *list)
> {
> - int nr_pages, nr_moved = 0;
> + int nr_moved = 0;
> + struct lruvec *lruvec = NULL;
> LIST_HEAD(pages_to_free);
> - struct page *page;
>
> while (!list_empty(list)) {
> - page = lru_to_page(list);
> + int nr_pages;
> + struct folio *folio = lru_to_folio(list);
> + struct page *page = &folio->page;
> +
> + lruvec = folio_lruvec_relock_irq(folio, lruvec);
> VM_BUG_ON_PAGE(PageLRU(page), page);
> list_del(&page->lru);
> if (unlikely(!page_evictable(page))) {
> - spin_unlock_irq(&lruvec->lru_lock);
> + unlock_page_lruvec_irq(lruvec);
Better to stick with the opencoded unlock. It matches a bit better
with the locking function, compared to locking folio and unlocking
page...
Aside from that, this looks good:
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
