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 4.4-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-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From ef70762948dde012146926720b70e79736336764 Mon Sep 17 00:00:00 2001 From: Yu Zhao <yuzhao@xxxxxxxxxx> Date: Fri, 16 Jun 2017 14:02:31 -0700 Subject: swap: cond_resched in swap_cgroup_prepare() From: Yu Zhao <yuzhao@xxxxxxxxxx> 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@xxxxxxxxxx Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/swap_cgroup.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/swap_cgroup.c +++ b/mm/swap_cgroup.c @@ -48,6 +48,9 @@ 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@xxxxxxxxxx are queue-4.4/swap-cond_resched-in-swap_cgroup_prepare.patch