Patch "swap: cond_resched in swap_cgroup_prepare()" has been added to the 3.18-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    swap: cond_resched in swap_cgroup_prepare()

to the 3.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     swap-cond_resched-in-swap_cgroup_prepare.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ef70762948dde012146926720b70e79736336764 Mon Sep 17 00:00:00 2001
From: Yu Zhao <yuzhao@google.com>
Date: Fri, 16 Jun 2017 14:02:31 -0700
Subject: swap: cond_resched in swap_cgroup_prepare()

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:


Patches currently in stable-queue which might be from yuzhao@google.com are

queue-3.18/swap-cond_resched-in-swap_cgroup_prepare.patch