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>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2423685..1c3df77 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -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);
+ 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]);
-
- 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);
@@ -1878,11 +1882,19 @@ 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]);
+ nr_moved += nr_pages;
+ if (PageActive(page))
+ workingset_age_nonresident(lruvec, nr_pages);
}
/*