| From 1f5320d5972aa50d3e8d2b227b636b370e608359 Mon Sep 17 00:00:00 2001 |
| From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> |
| Date: Thu, 4 Oct 2012 16:37:16 +0900 |
| Subject: cgroup: notify_on_release may not be triggered in some cases |
| |
| From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> |
| |
| commit 1f5320d5972aa50d3e8d2b227b636b370e608359 upstream. |
| |
| notify_on_release must be triggered when the last process in a cgroup is |
| move to another. But if the first(and only) process in a cgroup is moved to |
| another, notify_on_release is not triggered. |
| |
| # mkdir /cgroup/cpu/SRC |
| # mkdir /cgroup/cpu/DST |
| # |
| # echo 1 >/cgroup/cpu/SRC/notify_on_release |
| # echo 1 >/cgroup/cpu/DST/notify_on_release |
| # |
| # sleep 300 & |
| [1] 8629 |
| # |
| # echo 8629 >/cgroup/cpu/SRC/tasks |
| # echo 8629 >/cgroup/cpu/DST/tasks |
| -> notify_on_release for /SRC must be triggered at this point, |
| but it isn't. |
| |
| This is because put_css_set() is called before setting CGRP_RELEASABLE |
| in cgroup_task_migrate(), and is a regression introduce by the |
| commit:74a1166d(cgroups: make procs file writable), which was merged |
| into v3.0. |
| |
| Acked-by: Li Zefan <lizefan@huawei.com> |
| Cc: Ben Blum <bblum@andrew.cmu.edu> |
| Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> |
| Signed-off-by: Tejun Heo <tj@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| kernel/cgroup.c | 3 +-- |
| 1 file changed, 1 insertion(+), 2 deletions(-) |
| |
| --- a/kernel/cgroup.c |
| +++ b/kernel/cgroup.c |
| @@ -1868,9 +1868,8 @@ static void cgroup_task_migrate(struct c |
| * trading it for newcg is protected by cgroup_mutex, we're safe to drop |
| * it here; it will be freed under RCU. |
| */ |
| - put_css_set(oldcg); |
| - |
| set_bit(CGRP_RELEASABLE, &oldcgrp->flags); |
| + put_css_set(oldcg); |
| } |
| |
| /** |
