[PATCH 2/8] thp, mm: avoid PageUnevictable on active/inactive lru lists
From: Kirill A. Shutemov <hidden>
Date: 2013-06-11 15:35:13
Also in:
linux-fsdevel, lkml
Subsystem:
memory management, memory management - mglru (multi-gen lru), memory management - swap, memory management - thp (transparent huge page), the rest · Maintainers:
Andrew Morton, Chris Li, Kairui Song, David Hildenbrand, Lorenzo Stoakes, Linus Torvalds
From: "Kirill A. Shutemov" <redacted>
active/inactive lru lists can contain unevicable pages (i.e. ramfs pages
that have been placed on the LRU lists when first allocated), but these
pages must not have PageUnevictable set - otherwise shrink_[in]active_list
goes crazy:
kernel BUG at /home/space/kas/git/public/linux-next/mm/vmscan.c:1122!
1090 static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
1091 struct lruvec *lruvec, struct list_head *dst,
1092 unsigned long *nr_scanned, struct scan_control *sc,
1093 isolate_mode_t mode, enum lru_list lru)
1094 {
...
1108 switch (__isolate_lru_page(page, mode)) {
1109 case 0:
...
1116 case -EBUSY:
...
1121 default:
1122 BUG();
1123 }
1124 }
...
1130 }
__isolate_lru_page() returns EINVAL for PageUnevictable(page).
For lru_add_page_tail(), it means we should not set PageUnevictable()
for tail pages unless we're sure that it will go to LRU_UNEVICTABLE.
Let's just copy PG_active and PG_unevictable from head page in
__split_huge_page_refcount(), it will simplify lru_add_page_tail().
This will fix one more bug in lru_add_page_tail():
if page_evictable(page_tail) is false and PageLRU(page) is true, page_tail
will go to the same lru as page, but nobody cares to sync page_tail
active/inactive state with page. So we can end up with inactive page on
active lru.
The patch will fix it as well since we copy PG_active from head page.
Signed-off-by: Kirill A. Shutemov <redacted>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
---
mm/huge_memory.c | 4 +++-
mm/swap.c | 20 ++------------------
2 files changed, 5 insertions(+), 19 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index ed26ccb..d94f7de 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -1625,7 +1625,9 @@ static void __split_huge_page_refcount(struct page *page, ((1L << PG_referenced) | (1L << PG_swapbacked) | (1L << PG_mlocked) | - (1L << PG_uptodate))); + (1L << PG_uptodate) | + (1L << PG_active) | + (1L << PG_unevictable))); page_tail->flags |= (1L << PG_dirty); /* clear PageTail before overwriting first_page */
diff --git a/mm/swap.c b/mm/swap.c
index 2056d54..a19d4e5 100644
--- a/mm/swap.c
+++ b/mm/swap.c@@ -770,8 +770,6 @@ EXPORT_SYMBOL(__pagevec_release); void lru_add_page_tail(struct page *page, struct page *page_tail, struct lruvec *lruvec, struct list_head *list) { - int uninitialized_var(active); - enum lru_list lru; const int file = 0; VM_BUG_ON(!PageHead(page));
@@ -783,20 +781,6 @@ void lru_add_page_tail(struct page *page, struct page *page_tail, if (!list) SetPageLRU(page_tail); - if (page_evictable(page_tail)) { - if (PageActive(page)) { - SetPageActive(page_tail); - active = 1; - lru = LRU_ACTIVE_ANON; - } else { - active = 0; - lru = LRU_INACTIVE_ANON; - } - } else { - SetPageUnevictable(page_tail); - lru = LRU_UNEVICTABLE; - } - if (likely(PageLRU(page))) list_add_tail(&page_tail->lru, &page->lru); else if (list) {
@@ -812,13 +796,13 @@ void lru_add_page_tail(struct page *page, struct page *page_tail, * Use the standard add function to put page_tail on the list, * but then correct its position so they all end up in order. */ - add_page_to_lru_list(page_tail, lruvec, lru); + add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail)); list_head = page_tail->lru.prev; list_move_tail(&page_tail->lru, list_head); } if (!PageUnevictable(page)) - update_page_reclaim_stat(lruvec, file, active); + update_page_reclaim_stat(lruvec, file, PageActive(page_tail)); } #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
--
1.7.10.4
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