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 here for list intergrity.
Otherwise:
#0 mave_pages_to_lru #1 release_pages
if (put_page_testzero())
if !put_page_testzero
!PageLRU //skip lru_lock
list_add(&page->lru,)
list_add(&page->lru,) //corrupt
[[email protected]: coding style fixes]
Signed-off-by: Alex Shi <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
mm/vmscan.c | 37 ++++++++++++++++++++++++-------------
1 file changed, 24 insertions(+), 13 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 749d239c62b2..ddb29d813d77 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1856,26 +1856,29 @@ 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 intergrity.
+ * Otherwise:
+ * #0 mave_pages_to_lru #1 release_pages
+ * if (put_page_testzero())
+ * if !put_page_testzero
+ * !PageLRU //skip lru_lock
+ * list_add(&page->lru,)
+ * list_add(&page->lru,) //corrupt
+ */
SetPageLRU(page);
- lru = page_lru(page);
- nr_pages = hpage_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);
@@ -1883,11 +1886,19 @@ 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 = hpage_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);
}
/*
--
1.8.3.1