[patch] mm: memcontrol: fold move_anon() and move_file()

Johannes Weiner
2015-01-13T18:59:52Z

Turn the move type enum into flags and give the flags field a shorter
name. Once that is done, move_anon() and move_file() are simple
enough to just fold them into the callsites.

Signed-off-by: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
---
mm/memcontrol.c | 49 ++++++++++++++++++-------------------------------
1 file changed, 18 insertions(+), 31 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5a5769e8b12c..692e96407627 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -360,21 +360,18 @@ static bool memcg_kmem_is_active(struct mem_cgroup *memcg)

/* Stuffs for move charges at task migration. */
/*
- * Types of charges to be moved. "move_charge_at_immitgrate" and
- * "immigrate_flags" are treated as a left-shifted bitmap of these types.
+ * Types of charges to be moved.
*/
-enum move_type {
- MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */
- MOVE_CHARGE_TYPE_FILE, /* file page(including tmpfs) and swap of it */
- NR_MOVE_TYPE,
-};
+#define MOVE_ANON 0x1U
+#define MOVE_FILE 0x2U
+#define MOVE_MASK 0x3U

/* "mc" and its members are protected by cgroup_mutex */
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 flags;
unsigned long precharge;
unsigned long moved_charge;
unsigned long moved_swap;
@@ -385,16 +382,6 @@ static struct move_charge_struct {
.waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
};

-static bool move_anon(void)
-{
- return test_bit(MOVE_CHARGE_TYPE_ANON, &mc.immigrate_flags);
-}
-
-static bool move_file(void)
-{
- return test_bit(MOVE_CHARGE_TYPE_FILE, &mc.immigrate_flags);
-}
-
/*
* Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
* limit reclaim to prevent infinite loops, if they ever occur.
@@ -3476,7 +3463,7 @@ static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);

- if (val >= (1 << NR_MOVE_TYPE))
+ if (val & ~MOVE_MASK)
return -EINVAL;

/*
@@ -4698,12 +4685,12 @@ static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
if (!page || !page_mapped(page))
return NULL;
if (PageAnon(page)) {
- /* we don't move shared anon */
- if (!move_anon())
+ if (!(mc.flags & MOVE_ANON))
return NULL;
- } else if (!move_file())
- /* we ignore mapcount for file pages */
- return NULL;
+ } else {
+ if (!(mc.flags & MOVE_FILE))
+ return NULL;
+ }
if (!get_page_unless_zero(page))
return NULL;

@@ -4717,7 +4704,7 @@ static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
struct page *page = NULL;
swp_entry_t ent = pte_to_swp_entry(ptent);

- if (!move_anon() || non_swap_entry(ent))
+ if (!(mc.flags & MOVE_ANON) || non_swap_entry(ent))
return NULL;
/*
* Because lookup_swap_cache() updates some statistics counter,
@@ -4746,7 +4733,7 @@ static struct page *mc_handle_file_pte(struct vm_area_struct *vma,

if (!vma->vm_file) /* anonymous vma */
return NULL;
- if (!move_file())
+ if (!(mc.flags & MOVE_FILE))
return NULL;

mapping = vma->vm_file->f_mapping;
@@ -4828,7 +4815,7 @@ static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,

page = pmd_page(pmd);
VM_BUG_ON_PAGE(!page || !PageHead(page), page);
- if (!move_anon())
+ if (!(mc.flags & MOVE_ANON))
return ret;
if (page->mem_cgroup == mc.from) {
ret = MC_TARGET_PAGE;
@@ -4970,15 +4957,15 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
struct task_struct *p = cgroup_taskset_first(tset);
int ret = 0;
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
- unsigned long move_charge_at_immigrate;
+ unsigned long move_flags;

/*
* 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) {
+ move_flags = ACCESS_ONCE(memcg->move_charge_at_immigrate);
+ if (move_flags) {
struct mm_struct *mm;
struct mem_cgroup *from = mem_cgroup_from_task(p);

@@ -4998,7 +4985,7 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
spin_lock(&mc.lock);
mc.from = from;
mc.to = memcg;
- mc.immigrate_flags = move_charge_at_immigrate;
+ mc.flags = move_flags;
spin_unlock(&mc.lock);
/* We set mc.moving_task later */

--
2.2.0