mm: memcontrol: remove obsolete kmemcg pinning tricks

As charges now pin the css explicitely, there is no more need for kmemcg
to acquire a proxy reference for outstanding pages during offlining, or
maintain state to identify such "dead" groups.

This was the last user of the uncharge functions' return values, so remove
them as well.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 19 deletions

diff --git a/mm/page_counter.c b/mm/page_counter.c
index f0cbc08..a009574 100644
--- a/mm/page_counter.c
+++ b/mm/page_counter.c
@@ -16,19 +16,14 @@
  * page_counter_cancel - take pages out of the local counter
  * @counter: counter
  * @nr_pages: number of pages to cancel
- *
- * Returns whether there are remaining pages in the counter.
  */
-int page_counter_cancel(struct page_counter *counter, unsigned long nr_pages)
+void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages)
 {
 	long new;
 
 	new = atomic_long_sub_return(nr_pages, &counter->count);
-
 	/* More uncharges than charges? */
 	WARN_ON_ONCE(new < 0);
-
-	return new > 0;
 }
 
 /**
@@ -117,23 +112,13 @@ failed:
  * page_counter_uncharge - hierarchically uncharge pages
  * @counter: counter
  * @nr_pages: number of pages to uncharge
- *
- * Returns whether there are remaining charges in @counter.
  */
-int page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages)
+void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages)
 {
 	struct page_counter *c;
-	int ret = 1;
 
-	for (c = counter; c; c = c->parent) {
-		int remainder;
-
-		remainder = page_counter_cancel(c, nr_pages);
-		if (c == counter && !remainder)
-			ret = 0;
-	}
-
-	return ret;
+	for (c = counter; c; c = c->parent)
+		page_counter_cancel(c, nr_pages);
 }
 
 /**