diff options
| author | Tejun Heo <tj@kernel.org> | 2015-09-11 15:00:19 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2015-09-22 12:46:53 -0400 |
| commit | 4530eddb59494b89650d6bcd980fc7f7717ad80c (patch) | |
| tree | 0f6212afa2e7e0e4724c5f12644508f1a0baf138 /mm/memcontrol.c | |
| parent | 3df9ca0a2b8b50db5a079ae9d97c5b55435e9a6c (diff) | |
cgroup, memcg, cpuset: implement cgroup_taskset_for_each_leader()
It wasn't explicitly documented but, when a process is being migrated,
cpuset and memcg depend on cgroup_taskset_first() returning the
threadgroup leader; however, this approach is somewhat ghetto and
would no longer work for the planned multi-process migration.
This patch introduces explicit cgroup_taskset_for_each_leader() which
iterates over only the threadgroup leaders and replaces
cgroup_taskset_first() usages for accessing the leader with it.
This prepares both memcg and cpuset for multi-process migration. This
patch also updates the documentation for cgroup_taskset_for_each() to
clarify the iteration rules and removes comments mentioning task
ordering in tasksets.
v2: A previous patch which added threadgroup leader test was dropped.
Patch updated accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 9f331402e502..33c8dad6830f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4828,7 +4828,7 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css, { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup *from; - struct task_struct *p; + struct task_struct *leader, *p; struct mm_struct *mm; unsigned long move_flags; int ret = 0; @@ -4842,7 +4842,20 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css, if (!move_flags) return 0; - p = cgroup_taskset_first(tset); + /* + * Multi-process migrations only happen on the default hierarchy + * where charge immigration is not used. Perform charge + * immigration if @tset contains a leader and whine if there are + * multiple. + */ + p = NULL; + cgroup_taskset_for_each_leader(leader, tset) { + WARN_ON_ONCE(p); + p = leader; + } + if (!p) + return 0; + from = mem_cgroup_from_task(p); VM_BUG_ON(from == memcg); |