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-rw-r--r--mm/memcontrol.c32
1 files changed, 19 insertions, 13 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ae04338..8e0988fe 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -416,8 +416,8 @@ static bool memcg_kmem_test_and_clear_dead(struct mem_cgroup *memcg)
/* Stuffs for move charges at task migration. */
/*
- * Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
- * left-shifted bitmap of these types.
+ * Types of charges to be moved. "move_charge_at_immitgrate" and
+ * "immigrate_flags" are treated as a left-shifted bitmap of these types.
*/
enum move_type {
MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */
@@ -430,6 +430,7 @@ static struct move_charge_struct {
spinlock_t lock; /* for from, to */
struct mem_cgroup *from;
struct mem_cgroup *to;
+ unsigned long immigrate_flags;
unsigned long precharge;
unsigned long moved_charge;
unsigned long moved_swap;
@@ -442,14 +443,12 @@ static struct move_charge_struct {
static bool move_anon(void)
{
- return test_bit(MOVE_CHARGE_TYPE_ANON,
- &mc.to->move_charge_at_immigrate);
+ return test_bit(MOVE_CHARGE_TYPE_ANON, &mc.immigrate_flags);
}
static bool move_file(void)
{
- return test_bit(MOVE_CHARGE_TYPE_FILE,
- &mc.to->move_charge_at_immigrate);
+ return test_bit(MOVE_CHARGE_TYPE_FILE, &mc.immigrate_flags);
}
/*
@@ -5193,15 +5192,14 @@ static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
if (val >= (1 << NR_MOVE_TYPE))
return -EINVAL;
+
/*
- * We check this value several times in both in can_attach() and
- * attach(), so we need cgroup lock to prevent this value from being
- * inconsistent.
+ * No kind of locking is needed in here, because ->can_attach() will
+ * check this value once in the beginning of the process, and then carry
+ * on with stale data. This means that changes to this value will only
+ * affect task migrations starting after the change.
*/
- cgroup_lock();
memcg->move_charge_at_immigrate = val;
- cgroup_unlock();
-
return 0;
}
#else
@@ -6559,8 +6557,15 @@ static int mem_cgroup_can_attach(struct cgroup *cgroup,
struct task_struct *p = cgroup_taskset_first(tset);
int ret = 0;
struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup);
+ unsigned long move_charge_at_immigrate;
- if (memcg->move_charge_at_immigrate) {
+ /*
+ * We are now commited to this value whatever it is. Changes in this
+ * tunable will only affect upcoming migrations, not the current one.
+ * So we need to save it, and keep it going.
+ */
+ move_charge_at_immigrate = memcg->move_charge_at_immigrate;
+ if (move_charge_at_immigrate) {
struct mm_struct *mm;
struct mem_cgroup *from = mem_cgroup_from_task(p);
@@ -6580,6 +6585,7 @@ static int mem_cgroup_can_attach(struct cgroup *cgroup,
spin_lock(&mc.lock);
mc.from = from;
mc.to = memcg;
+ mc.immigrate_flags = move_charge_at_immigrate;
spin_unlock(&mc.lock);
/* We set mc.moving_task later */
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