From e20dc86b22bb80a151dc79fbfbc1b0f31fb54aea Mon Sep 17 00:00:00 2001 From: Alex Shi <alex.shi@linux.alibaba.com> Date: Tue, 15 Dec 2020 12:33:37 -0800 Subject: [PATCH] mm/vmscan: remove unnecessary lruvec adding MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We don't have to add a freeable page into lru and then remove from it. This change saves a couple of actions and makes the moving more clear. The SetPageLRU needs to be kept before put_page_testzero for list integrity, otherwise: #0 move_pages_to_lru #1 release_pages if !put_page_testzero if (put_page_testzero()) !PageLRU //skip lru_lock SetPageLRU() list_add(&page->lru,) list_add(&page->lru,) [akpm@linux-foundation.org: coding style fixes] Link: https://lkml.kernel.org/r/1604566549-62481-6-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: "Chen, Rong A" <rong.a.chen@intel.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- mm/vmscan.c | 40 ++++++++++++++++++++++++++-------------- 1 file changed, 26 insertions(+), 14 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 093dd5314..e7b2ea321 100755 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1942,27 +1942,30 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec, while (!list_empty(list)) { page = lru_to_page(list); VM_BUG_ON_PAGE(PageLRU(page), page); + list_del(&page->lru); if (unlikely(!page_evictable(page))) { - list_del(&page->lru); spin_unlock_irq(&pgdat->lru_lock); putback_lru_page(page); spin_lock_irq(&pgdat->lru_lock); continue; } - lruvec = mem_cgroup_page_lruvec(page, pgdat); + /* + * The SetPageLRU needs to be kept here for list integrity. + * Otherwise: + * #0 move_pages_to_lru #1 release_pages + * if !put_page_testzero + * if (put_page_testzero()) + * !PageLRU //skip lru_lock + * SetPageLRU() + * list_add(&page->lru,) + * list_add(&page->lru,) + */ SetPageLRU(page); - lru = page_lru(page); - nr_pages = thp_nr_pages(page); - update_lru_size(lruvec, lru, page_zonenum(page), nr_pages); - list_move(&page->lru, &lruvec->lists[lru]); - trace_android_vh_add_page_to_lrulist(page, false, lru); - - if (put_page_testzero(page)) { + if (unlikely(put_page_testzero(page))) { __ClearPageLRU(page); __ClearPageActive(page); - del_page_from_lru_list(page, lruvec, lru); if (unlikely(PageCompound(page))) { spin_unlock_irq(&pgdat->lru_lock); @@ -1970,11 +1973,20 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec, spin_lock_irq(&pgdat->lru_lock); } else list_add(&page->lru, &pages_to_free); - } else { - nr_moved += nr_pages; - if (PageActive(page)) - workingset_age_nonresident(lruvec, nr_pages); + + continue; } + + lruvec = mem_cgroup_page_lruvec(page, pgdat); + lru = page_lru(page); + nr_pages = thp_nr_pages(page); + + update_lru_size(lruvec, lru, page_zonenum(page), nr_pages); + list_add(&page->lru, &lruvec->lists[lru]); + trace_android_vh_add_page_to_lrulist(page, false, lru); + nr_moved += nr_pages; + if (PageActive(page)) + workingset_age_nonresident(lruvec, nr_pages); } /*