Commit 3d06afab authored Dec 15, 2020 by Alex Shi Committed by Linus Torvalds Dec 15, 2020

mm/vmscan: remove unnecessary lruvec adding

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>

parent b6769834

mm/vmscan.c

+25 −13

Original line number	Diff line number	Diff line
		@@ -1851,26 +1851,30 @@ 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);
		if (unlikely(!page_evictable(page))) {
		list_del(&page->lru);
		if (unlikely(!page_evictable(page))) {
		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]);

		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);
		@@ -1878,12 +1882,20 @@ 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 {

		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]);
		nr_moved += nr_pages;
		if (PageActive(page))
		workingset_age_nonresident(lruvec, nr_pages);
		}
		}

		/*
		* To save our caller's stack, now use input list for pages to free.

Admin message