Similar to page_off_lru(), the new function does non-atomic clearing of PageLRU() in addition to PageActive() and PageUnevictable(), on a page that has no references left. If PageActive() and PageUnevictable() are both set, refuse to clear either and leave them to bad_page(). This is a behavior change that is meant to help debug. Link: https://lore.kernel.org/linux-mm/20201207220949.830352-7-yuzhao@xxxxxxxxxx/ Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx> --- include/linux/mm_inline.h | 28 ++++++++++------------------ mm/swap.c | 6 ++---- mm/vmscan.c | 3 +-- 3 files changed, 13 insertions(+), 24 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index ffacc6273678..ef3fd79222e5 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -61,27 +61,19 @@ static inline enum lru_list page_lru_base_type(struct page *page) } /** - * page_off_lru - which LRU list was page on? clearing its lru flags. - * @page: the page to test - * - * Returns the LRU list a page was on, as an index into the array of LRU - * lists; and clears its Unevictable or Active flags, ready for freeing. + * __clear_page_lru_flags - clear page lru flags before releasing a page + * @page: the page that was on lru and now has a zero reference */ -static __always_inline enum lru_list page_off_lru(struct page *page) +static __always_inline void __clear_page_lru_flags(struct page *page) { - enum lru_list lru; + __ClearPageLRU(page); - if (PageUnevictable(page)) { - __ClearPageUnevictable(page); - lru = LRU_UNEVICTABLE; - } else { - lru = page_lru_base_type(page); - if (PageActive(page)) { - __ClearPageActive(page); - lru += LRU_ACTIVE; - } - } - return lru; + /* this shouldn't happen, so leave the flags to bad_page() */ + if (PageActive(page) && PageUnevictable(page)) + return; + + __ClearPageActive(page); + __ClearPageUnevictable(page); } /** diff --git a/mm/swap.c b/mm/swap.c index 94532799ed82..38900d672051 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -84,9 +84,8 @@ static void __page_cache_release(struct page *page) lruvec = lock_page_lruvec_irqsave(page, &flags); VM_BUG_ON_PAGE(!PageLRU(page), page); - __ClearPageLRU(page); del_page_from_lru_list(page, lruvec); - page_off_lru(page); + __clear_page_lru_flags(page); unlock_page_lruvec_irqrestore(lruvec, flags); } __ClearPageWaiters(page); @@ -911,9 +910,8 @@ void release_pages(struct page **pages, int nr) lock_batch = 0; VM_BUG_ON_PAGE(!PageLRU(page), page); - __ClearPageLRU(page); del_page_from_lru_list(page, lruvec); - page_off_lru(page); + __clear_page_lru_flags(page); } __ClearPageWaiters(page); diff --git a/mm/vmscan.c b/mm/vmscan.c index 7c65d47e6612..452dd3818aa3 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1849,8 +1849,7 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec, SetPageLRU(page); if (unlikely(put_page_testzero(page))) { - __ClearPageLRU(page); - __ClearPageActive(page); + __clear_page_lru_flags(page); if (unlikely(PageCompound(page))) { spin_unlock_irq(&lruvec->lru_lock); -- 2.30.0.280.ga3ce27912f-goog
