On Thu 17-09-20 21:00:41, Yu Zhao wrote:
> Now we have a total of three places that free lru pages when their
> references become zero (after we drop the reference from isolation).
>
> Before this patch, they all do:
> __ClearPageLRU()
> page_off_lru()
> del_page_from_lru_list()
>
> After this patch, they become:
> page_off_lru()
> __ClearPageLRU()
> del_page_from_lru_list()
>
> This change should have no side effects.
Again, why this is desirable?
> Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
> ---
> include/linux/mm_inline.h | 1 +
> mm/swap.c | 2 --
> mm/vmscan.c | 1 -
> 3 files changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
> index 8fc71e9d7bb0..be9418425e41 100644
> --- a/include/linux/mm_inline.h
> +++ b/include/linux/mm_inline.h
> @@ -92,6 +92,7 @@ static __always_inline enum lru_list page_off_lru(struct page *page)
> {
> enum lru_list lru;
>
> + __ClearPageLRU(page);
> if (PageUnevictable(page)) {
> __ClearPageUnevictable(page);
> lru = LRU_UNEVICTABLE;
> diff --git a/mm/swap.c b/mm/swap.c
> index 40bf20a75278..8362083f00c9 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -86,7 +86,6 @@ static void __page_cache_release(struct page *page)
> spin_lock_irqsave(&pgdat->lru_lock, flags);
> lruvec = mem_cgroup_page_lruvec(page, pgdat);
> VM_BUG_ON_PAGE(!PageLRU(page), page);
> - __ClearPageLRU(page);
> del_page_from_lru_list(page, lruvec, page_off_lru(page));
> spin_unlock_irqrestore(&pgdat->lru_lock, flags);
> }
> @@ -895,7 +894,6 @@ void release_pages(struct page **pages, int nr)
>
> lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
> VM_BUG_ON_PAGE(!PageLRU(page), page);
> - __ClearPageLRU(page);
> del_page_from_lru_list(page, lruvec, page_off_lru(page));
> }
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index f257d2f61574..f9a186a96410 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1862,7 +1862,6 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
> add_page_to_lru_list(page, lruvec, lru);
>
> if (put_page_testzero(page)) {
> - __ClearPageLRU(page);
> del_page_from_lru_list(page, lruvec, page_off_lru(page));
>
> if (unlikely(PageCompound(page))) {
> --
> 2.28.0.681.g6f77f65b4e-goog
--
Michal Hocko
SUSE Labs
