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authorHugh Dickins <hughd@google.com>2012-01-12 17:19:52 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-12 20:13:09 -0800
commit12d27107867fc7216e8faaff0b894b0f162dcf75 (patch)
tree8f35d39f7e5d0b0f0ba10a3475e9fa4a2581e509 /mm/swap.c
parent0cee34fd72c582b4f8ad8ce00645b75fb4168199 (diff)
memcg: fix split_huge_page_refcounts()
This patch started off as a cleanup: __split_huge_page_refcounts() has to cope with two scenarios, when the hugepage being split is already on LRU, and when it is not; but why does it have to split that accounting across three different sites? Consolidate it in lru_add_page_tail(), handling evictable and unevictable alike, and use standard add_page_to_lru_list() when accounting is needed (when the head is not yet on LRU). But a recent regression in -next, I guess the removal of PageCgroupAcctLRU test from mem_cgroup_split_huge_fixup(), makes this now a necessary fix: under load, the MEM_CGROUP_ZSTAT count was wrapping to a huge number, messing up reclaim calculations and causing a freeze at rmdir of cgroup. Add a VM_BUG_ON to mem_cgroup_lru_del_list() when we're about to wrap that count - this has not been the only such incident. Document that lru_add_page_tail() is for Transparent HugePages by #ifdef around it. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/swap.c')
-rw-r--r--mm/swap.c29
1 files changed, 19 insertions, 10 deletions
diff --git a/mm/swap.c b/mm/swap.c
index ddccf8e0b4a..db6defaf2e5 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -650,6 +650,7 @@ void __pagevec_release(struct pagevec *pvec)
EXPORT_SYMBOL(__pagevec_release);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/* used by __split_huge_page_refcount() */
void lru_add_page_tail(struct zone* zone,
struct page *page, struct page *page_tail)
@@ -666,8 +667,6 @@ void lru_add_page_tail(struct zone* zone,
SetPageLRU(page_tail);
if (page_evictable(page_tail, NULL)) {
- struct lruvec *lruvec;
-
if (PageActive(page)) {
SetPageActive(page_tail);
active = 1;
@@ -677,18 +676,28 @@ void lru_add_page_tail(struct zone* zone,
lru = LRU_INACTIVE_ANON;
}
update_page_reclaim_stat(zone, page_tail, file, active);
- lruvec = mem_cgroup_lru_add_list(zone, page_tail, lru);
- if (likely(PageLRU(page)))
- list_add(&page_tail->lru, page->lru.prev);
- else
- list_add(&page_tail->lru, lruvec->lists[lru].prev);
- __mod_zone_page_state(zone, NR_LRU_BASE + lru,
- hpage_nr_pages(page_tail));
} else {
SetPageUnevictable(page_tail);
- add_page_to_lru_list(zone, page_tail, LRU_UNEVICTABLE);
+ lru = LRU_UNEVICTABLE;
+ }
+
+ if (likely(PageLRU(page)))
+ list_add_tail(&page_tail->lru, &page->lru);
+ else {
+ struct list_head *list_head;
+ /*
+ * Head page has not yet been counted, as an hpage,
+ * so we must account for each subpage individually.
+ *
+ * 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(zone, page_tail, lru);
+ list_head = page_tail->lru.prev;
+ list_move_tail(&page_tail->lru, list_head);
}
}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
static void ____pagevec_lru_add_fn(struct page *page, void *arg)
{