[PATCH 3.18 29/32] swap: cond_resched in swap_cgroup_prepare()

From	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups	linux.kernel
Subject	[PATCH 3.18 29/32] swap: cond_resched in swap_cgroup_prepare()
Date	2017-06-19 17:40 +0200
Message-ID	<tU6Wv-4tx-47@gated-at.bofh.it> (permalink)
References	<tU6Wt-4tx-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yu Zhao <yuzhao@google.com>

commit ef70762948dde012146926720b70e79736336764 upstream.

I saw need_resched() warnings when swapping on large swapfile (TBs)
because continuously allocating many pages in swap_cgroup_prepare() took
too long.

We already cond_resched when freeing page in swap_cgroup_swapoff().  Do
the same for the page allocation.

Link: http://lkml.kernel.org/r/20170604200109.17606-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 mm/page_cgroup.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -368,6 +368,9 @@ static int swap_cgroup_prepare(int type)
 		if (!page)
 			goto not_enough_page;
 		ctrl->map[idx] = page;
+
+		if (!(idx % SWAP_CLUSTER_MAX))
+			cond_resched();
 	}
 	return 0;
 not_enough_page:

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[PATCH 3.18 29/32] swap: cond_resched in swap_cgroup_prepare() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-19 17:40 +0200

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