This patch implements force_empty of swapcgroup.
Currently, it simply uncharges all the charges from the group.
I think there can be other implementations.
What I thought are:
- move all the charges to its parent.
- unuse(swap in) all the swap charged to the group.
But in any case, I think before implementing this way,
hierarchy and move charges support are needed.
So I think this is enough for the first step.
Change log
v2->v3
- new patch
Signed-off-by: Daisuke Nishimura <[EMAIL PROTECTED]>
---
include/linux/memcontrol.h | 5 ++++
mm/memcontrol.c | 47 +++++++++++++++++++++++++++++++--------
mm/swapfile.c | 52 +++++++++++++++++++++++++++++++++++++++++--
3 files changed, 91 insertions(+), 13 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 1e6eb0c..8c4bad0 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -177,6 +177,7 @@ extern void swap_cgroup_uncharge(struct swap_info_struct
*si,
unsigned long offset);
extern struct mem_cgroup *page_to_memcg(struct page *page);
extern int swap_cgroup_vm_swap_full(struct mem_cgroup *memcg);
+extern void __swap_cgroup_force_empty(struct mem_cgroup *mem);
#else
static inline
struct mem_cgroup **swap_info_clear_memcg(struct swap_info_struct *p)
@@ -211,6 +212,10 @@ static inline int swap_cgroup_vm_swap_full(struct
mem_cgroup *memcg)
{
return 0;
}
+
+static inline void __swap_cgroup_force_empty(struct mem_cgroup *mem)
+{
+}
#endif
#endif /* _LINUX_MEMCONTROL_H */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 160fca1..f93907c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -826,6 +826,34 @@ static void mem_cgroup_force_empty_list(struct mem_cgroup
*mem,
spin_unlock_irqrestore(&mz->lru_lock, flags);
}
+static inline int mem_cgroup_in_use(struct mem_cgroup *mem)
+{
+ return mem->res.usage > 0;
+}
+
+static inline int swap_cgroup_in_use(struct mem_cgroup *mem)
+{
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+ return mem->swap_res.usage > 0;
+#else
+ return 0;
+#endif
+}
+
+static void __mem_cgroup_force_empty(struct mem_cgroup *mem)
+{
+ int node, zid;
+
+ for_each_node_state(node, N_POSSIBLE)
+ for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+ struct mem_cgroup_per_zone *mz;
+ enum lru_list l;
+ mz = mem_cgroup_zoneinfo(mem, node, zid);
+ for_each_lru(l)
+ mem_cgroup_force_empty_list(mem, mz, l);
+ }
+}
+
/*
* make mem_cgroup's charge to be 0 if there is no task.
* This enables deleting this mem_cgroup.
@@ -833,7 +861,6 @@ static void mem_cgroup_force_empty_list(struct mem_cgroup
*mem,
static int mem_cgroup_force_empty(struct mem_cgroup *mem)
{
int ret = -EBUSY;
- int node, zid;
css_get(&mem->css);
/*
@@ -841,18 +868,17 @@ static int mem_cgroup_force_empty(struct mem_cgroup *mem)
* active_list <-> inactive_list while we don't take a lock.
* So, we have to do loop here until all lists are empty.
*/
- while (mem->res.usage > 0) {
+ while (mem_cgroup_in_use(mem) || swap_cgroup_in_use(mem)) {
if (atomic_read(&mem->css.cgroup->count) > 0)
goto out;
- for_each_node_state(node, N_POSSIBLE)
- for (zid = 0; zid < MAX_NR_ZONES; zid++) {
- struct mem_cgroup_per_zone *mz;
- enum lru_list l;
- mz = mem_cgroup_zoneinfo(mem, node, zid);
- for_each_lru(l)
- mem_cgroup_force_empty_list(mem, mz, l);
- }
+
+ if (mem_cgroup_in_use(mem))
+ __mem_cgroup_force_empty(mem);
+
+ if (swap_cgroup_in_use(mem))
+ __swap_cgroup_force_empty(mem);
}
+
ret = 0;
out:
css_put(&mem->css);
@@ -1289,6 +1315,7 @@ void swap_cgroup_uncharge(struct swap_info_struct *si,
* and called swap_entry_free().
* 2. when this swap entry had been assigned by
* get_swap_page_of_type() (via SWSUSP?).
+ * 3. force empty can make such entries.
*/
if (mem) {
res_counter_uncharge(&mem->swap_res, PAGE_SIZE);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 6a863bc..2263ae8 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -704,15 +704,30 @@ static int unuse_mm(struct mm_struct *mm,
}
/*
+ * return the mem_cgroup to which a entry is charged
+ */
+static inline struct mem_cgroup *entry_to_memcg(swp_entry_t entry)
+{
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+ return swap_info[swp_type(entry)].memcg[swp_offset(entry)];
+#else
+ return NULL;
+#endif
+}
+
+/*
* Scan swap_map from current position to next entry still in use.
+ * If mem is specified, the entry should be charged to it.
* Recycle to start on reaching the end, returning 0 when empty.
*/
static unsigned int find_next_to_unuse(struct swap_info_struct *si,
- unsigned int prev)
+ unsigned int prev,
+ struct mem_cgroup *mem)
{
unsigned int max = si->max;
unsigned int i = prev;
int count;
+ int type = si - swap_info;
/*
* No need for swap_lock here: we're just looking
@@ -735,7 +750,8 @@ static unsigned int find_next_to_unuse(struct
swap_info_struct *si,
i = 1;
}
count = si->swap_map[i];
- if (count && count != SWAP_MAP_BAD)
+ if (count && count != SWAP_MAP_BAD
+ && (!mem || mem == entry_to_memcg(swp_entry(type, i))))
break;
}
return i;
@@ -782,7 +798,7 @@ static int try_to_unuse(unsigned int type)
* one pass through swap_map is enough, but not necessarily:
* there are races when an instance of an entry might be missed.
*/
- while ((i = find_next_to_unuse(si, i)) != 0) {
+ while ((i = find_next_to_unuse(si, i, NULL)) != 0) {
if (signal_pending(current)) {
retval = -EINTR;
break;
@@ -1923,5 +1939,35 @@ struct mem_cgroup *page_to_memcg(struct page *page)
out:
return mem;
}
+
+/*
+ * uncharge all the entries that are charged to the group.
+ */
+void __swap_cgroup_force_empty(struct mem_cgroup *mem)
+{
+ struct swap_info_struct *p;
+ int type;
+
+ spin_lock(&swap_lock);
+ for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
+ p = swap_info + type;
+
+ if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
+ unsigned int i = 0;
+
+ spin_unlock(&swap_lock);
+ while ((i = find_next_to_unuse(p, i, mem)) != 0) {
+ spin_lock(&swap_lock);
+ if (p->swap_map[i] && p->memcg[i] == mem)
+ swap_cgroup_uncharge(p, i);
+ spin_unlock(&swap_lock);
+ }
+ spin_lock(&swap_lock);
+ }
+ }
+ spin_unlock(&swap_lock);
+
+ return;
+}
#endif
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