From b1355226a64e6301ca63aee1e78728887e3527f1 Mon Sep 17 00:00:00 2001
From: David Rientjes <rientjes@google.com>
Date: Fri, 7 Apr 2017 16:05:00 -0700
Subject: mm, swap_cgroup: reschedule when neeed in swap_cgroup_swapoff()

commit 460bcec84e11c75122ace5976214abbc596eb91b upstream.

We got need_resched() warnings in swap_cgroup_swapoff() because
swap_cgroup_ctrl[type].length is particularly large.

Reschedule when needed.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1704061315270.80559@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
index 454d6d7..3405b4e 100644
--- a/mm/swap_cgroup.c
+++ b/mm/swap_cgroup.c
@@ -204,6 +204,8 @@ void swap_cgroup_swapoff(int type)
 			struct page *page = map[i];
 			if (page)
 				__free_page(page);
+			if (!(i % SWAP_CLUSTER_MAX))
+				cond_resched();
 		}
 		vfree(map);
 	}
-- 
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