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authorTejun Heo <tj@kernel.org>2016-04-21 19:06:48 -0400
committerTejun Heo <tj@kernel.org>2016-04-25 15:45:14 -0400
commit5cf1cacb49aee39c3e02ae87068fc3c6430659b0 (patch)
tree569518d16093a55169e4ef1cd5399e9a3f620d06 /include/linux/cgroup-defs.h
parentbcc981e9ed84c678533299d7eff17d2c81e4d5de (diff)
cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback
Since e93ad19d0564 ("cpuset: make mm migration asynchronous"), cpuset kicks off asynchronous NUMA node migration if necessary during task migration and flushes it from cpuset_post_attach_flush() which is called at the end of __cgroup_procs_write(). This is to avoid performing migration with cgroup_threadgroup_rwsem write-locked which can lead to deadlock through dependency on kworker creation. memcg has a similar issue with charge moving, so let's convert it to an official callback rather than the current one-off cpuset specific function. This patch adds cgroup_subsys->post_attach callback and makes cpuset register cpuset_post_attach_flush() as its ->post_attach. The conversion is mostly one-to-one except that the new callback is called under cgroup_mutex. This is to guarantee that no other migration operations are started before ->post_attach callbacks are finished. cgroup_mutex is one of the outermost mutex in the system and has never been and shouldn't be a problem. We can add specialized synchronization around __cgroup_procs_write() but I don't think there's any noticeable benefit. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: <stable@vger.kernel.org> # 4.4+ prerequisite for the next patch
Diffstat (limited to 'include/linux/cgroup-defs.h')
-rw-r--r--include/linux/cgroup-defs.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 3e39ae5bc799..5b17de62c962 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -444,6 +444,7 @@ struct cgroup_subsys {
int (*can_attach)(struct cgroup_taskset *tset);
void (*cancel_attach)(struct cgroup_taskset *tset);
void (*attach)(struct cgroup_taskset *tset);
+ void (*post_attach)(void);
int (*can_fork)(struct task_struct *task);
void (*cancel_fork)(struct task_struct *task);
void (*fork)(struct task_struct *task);