From 16d3c016eabd1964657d5099ae745b57c9d6b10d Mon Sep 17 00:00:00 2001 From: Yu Zhao Date: Fri, 2 Oct 2020 01:54:36 -0600 Subject: [PATCH] BACKPORT: mm: add __clear_page_lru_flags() to replace page_off_lru() 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@google.com/ Link: https://lkml.kernel.org/r/20210122220600.906146-7-yuzhao@google.com Signed-off-by: Yu Zhao Cc: Alex Shi Cc: Hugh Dickins Cc: Johannes Weiner Cc: Matthew Wilcox Cc: Michal Hocko Cc: Roman Gushchin Cc: Vladimir Davydov Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds (cherry picked from commit 875601796267214f286d3581fe74f2805d060fe8) BUG=b:123039911 TEST=Built Change-Id: I86b973cd52a0ddb0fb1453c5fcd787aa885297e6 Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2940116 Tested-by: Yu Zhao Reviewed-by: Sonny Rao Commit-Queue: Yu Zhao --- include/linux/mm_inline.h | 28 ++++++++++------------------ mm/swap.c | 6 ++---- mm/vmscan.c | 3 +-- 3 files changed, 13 insertions(+), 24 deletions(-) --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -60,27 +60,19 @@ static inline enum lru_list page_lru_bas } /** - * 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); } /** --- a/mm/swap.c +++ b/mm/swap.c @@ -67,9 +67,8 @@ static void __page_cache_release(struct 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); + __clear_page_lru_flags(page); spin_unlock_irqrestore(&pgdat->lru_lock, flags); } __ClearPageWaiters(page); @@ -819,9 +818,8 @@ void release_pages(struct page **pages, 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); + __clear_page_lru_flags(page); } __ClearPageWaiters(page); --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1898,9 +1898,8 @@ static unsigned noinline_for_stack move_ add_page_to_lru_list(page, lruvec); if (put_page_testzero(page)) { - __ClearPageLRU(page); del_page_from_lru_list(page, lruvec); - __ClearPageActive(page); + __clear_page_lru_flags(page); if (unlikely(PageCompound(page))) { spin_unlock_irq(&pgdat->lru_lock);