cgroups: don't attach task to subsystem if migration failed
authorBen Blum <bblum@andrew.cmu.edu>
Wed, 2 Nov 2011 20:38:07 +0000 (13:38 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 2 Nov 2011 23:06:59 +0000 (16:06 -0700)
commit77ceab8ea590d7dc6c8f055ce43dfebd74428107
treeb2ef5e5baca4579565ab9bf527e965dd9b93a25a
parent33ef6b6984403a688189317ef46bb3caab3b70e0
cgroups: don't attach task to subsystem if migration failed

If a task has exited to the point it has called cgroup_exit() already,
then we can't migrate it to another cgroup anymore.

This can happen when we are attaching a task to a new cgroup between the
call to ->can_attach_task() on subsystems and the migration that is
eventually tried in cgroup_task_migrate().

In this case cgroup_task_migrate() returns -ESRCH and we don't want to
attach the task to the subsystems because the attachment to the new cgroup
itself failed.

Fix this by only calling ->attach_task() on the subsystems if the cgroup
migration succeeded.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Ben Blum <bblum@andrew.cmu.edu>
Acked-by: Paul Menage <paul@paulmenage.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/cgroup.c