aboutsummaryrefslogtreecommitdiff
path: root/mm
diff options
context:
space:
mode:
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
parent0cee34fd72c582b4f8ad8ce00645b75fb4168199 (diff)
downloadlinux-stericsson-12d27107867fc7216e8faaff0b894b0f162dcf75.tar.gz
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')
-rw-r--r--mm/huge_memory.c10
-rw-r--r--mm/memcontrol.c12
-rw-r--r--mm/swap.c29
3 files changed, 21 insertions, 30 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 76cc3f7dd4f0..b3ffc21ce801 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1229,7 +1229,6 @@ static void __split_huge_page_refcount(struct page *page)
{
int i;
struct zone *zone = page_zone(page);
- int zonestat;
int tail_count = 0;
/* prevent PageLRU to go away from under us, and freeze lru stats */
@@ -1317,15 +1316,6 @@ static void __split_huge_page_refcount(struct page *page)
__dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
__mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
- /*
- * A hugepage counts for HPAGE_PMD_NR pages on the LRU statistics,
- * so adjust those appropriately if this page is on the LRU.
- */
- if (PageLRU(page)) {
- zonestat = NR_LRU_BASE + page_lru(page);
- __mod_zone_page_state(zone, zonestat, -(HPAGE_PMD_NR-1));
- }
-
ClearPageCompound(page);
compound_unlock(page);
spin_unlock_irq(&zone->lru_lock);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 609c49f492e6..9f2f64697409 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1071,6 +1071,7 @@ void mem_cgroup_lru_del_list(struct page *page, enum lru_list lru)
VM_BUG_ON(!memcg);
mz = page_cgroup_zoneinfo(memcg, page);
/* huge page split is done under lru_lock. so, we have no races. */
+ VM_BUG_ON(MEM_CGROUP_ZSTAT(mz, lru) < (1 << compound_order(page)));
MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page);
}
@@ -2465,9 +2466,7 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
void mem_cgroup_split_huge_fixup(struct page *head)
{
struct page_cgroup *head_pc = lookup_page_cgroup(head);
- struct mem_cgroup_per_zone *mz;
struct page_cgroup *pc;
- enum lru_list lru;
int i;
if (mem_cgroup_disabled())
@@ -2478,15 +2477,8 @@ void mem_cgroup_split_huge_fixup(struct page *head)
smp_wmb();/* see __commit_charge() */
pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;
}
- /*
- * Tail pages will be added to LRU.
- * We hold lru_lock,then,reduce counter directly.
- */
- lru = page_lru(head);
- mz = page_cgroup_zoneinfo(head_pc->mem_cgroup, head);
- MEM_CGROUP_ZSTAT(mz, lru) -= HPAGE_PMD_NR - 1;
}
-#endif
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
/**
* mem_cgroup_move_account - move account of the page
diff --git a/mm/swap.c b/mm/swap.c
index ddccf8e0b4ae..db6defaf2e55 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)
{