memcg: restructure mem_cgroup_can_attach()
Restructure it to lower nesting level and help the planned threadgroup
leader iteration changes.
This is pure reorganization.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6935f77..191d8aa 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4834,10 +4834,12 @@
static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset)
{
- struct task_struct *p = cgroup_taskset_first(tset);
- int ret = 0;
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+ struct mem_cgroup *from;
+ struct task_struct *p;
+ struct mm_struct *mm;
unsigned long move_flags;
+ int ret = 0;
/*
* We are now commited to this value whatever it is. Changes in this
@@ -4845,36 +4847,37 @@
* So we need to save it, and keep it going.
*/
move_flags = READ_ONCE(memcg->move_charge_at_immigrate);
- if (move_flags) {
- struct mm_struct *mm;
- struct mem_cgroup *from = mem_cgroup_from_task(p);
+ if (!move_flags)
+ return 0;
- VM_BUG_ON(from == memcg);
+ p = cgroup_taskset_first(tset);
+ from = mem_cgroup_from_task(p);
- mm = get_task_mm(p);
- if (!mm)
- return 0;
- /* We move charges only when we move a owner of the mm */
- if (mm->owner == p) {
- VM_BUG_ON(mc.from);
- VM_BUG_ON(mc.to);
- VM_BUG_ON(mc.precharge);
- VM_BUG_ON(mc.moved_charge);
- VM_BUG_ON(mc.moved_swap);
+ VM_BUG_ON(from == memcg);
- spin_lock(&mc.lock);
- mc.from = from;
- mc.to = memcg;
- mc.flags = move_flags;
- spin_unlock(&mc.lock);
- /* We set mc.moving_task later */
+ mm = get_task_mm(p);
+ if (!mm)
+ return 0;
+ /* We move charges only when we move a owner of the mm */
+ if (mm->owner == p) {
+ VM_BUG_ON(mc.from);
+ VM_BUG_ON(mc.to);
+ VM_BUG_ON(mc.precharge);
+ VM_BUG_ON(mc.moved_charge);
+ VM_BUG_ON(mc.moved_swap);
- ret = mem_cgroup_precharge_mc(mm);
- if (ret)
- mem_cgroup_clear_mc();
- }
- mmput(mm);
+ spin_lock(&mc.lock);
+ mc.from = from;
+ mc.to = memcg;
+ mc.flags = move_flags;
+ spin_unlock(&mc.lock);
+ /* We set mc.moving_task later */
+
+ ret = mem_cgroup_precharge_mc(mm);
+ if (ret)
+ mem_cgroup_clear_mc();
}
+ mmput(mm);
return ret;
}