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-rw-r--r--Documentation/cgroups/memory.txt20
-rw-r--r--mm/memcontrol.c100
2 files changed, 111 insertions, 9 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 6cab1f2..eac22d3 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -184,6 +184,9 @@ limits on the root cgroup.
Note2: When panic_on_oom is set to "2", the whole system will panic.
+When oom event notifier is registered, event will be delivered.
+(See oom_control section)
+
2. Locking
The memory controller uses the following hierarchy
@@ -488,7 +491,22 @@ threshold in any direction.
It's applicable for root and non-root cgroup.
-10. TODO
+10. OOM Control
+
+Memory controler implements oom notifier using cgroup notification
+API (See cgroups.txt). It allows to register multiple oom notification
+delivery and gets notification when oom happens.
+
+To register a notifier, application need:
+ - create an eventfd using eventfd(2)
+ - open memory.oom_control file
+ - write string like "<event_fd> <memory.oom_control>" to cgroup.event_control
+
+Application will be notifier through eventfd when oom happens.
+OOM notification doesn't work for root cgroup.
+
+
+11. TODO
1. Add support for accounting huge pages (as a separate controller)
2. Make per-cgroup scanner reclaim not-shared pages first
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 94ac208..da2ed39 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -149,6 +149,7 @@ struct mem_cgroup_threshold {
u64 threshold;
};
+/* For threshold */
struct mem_cgroup_threshold_ary {
/* An array index points to threshold just below usage. */
atomic_t current_threshold;
@@ -157,8 +158,14 @@ struct mem_cgroup_threshold_ary {
/* Array of thresholds */
struct mem_cgroup_threshold entries[0];
};
+/* for OOM */
+struct mem_cgroup_eventfd_list {
+ struct list_head list;
+ struct eventfd_ctx *eventfd;
+};
static void mem_cgroup_threshold(struct mem_cgroup *mem);
+static void mem_cgroup_oom_notify(struct mem_cgroup *mem);
/*
* The memory controller data structure. The memory controller controls both
@@ -220,6 +227,9 @@ struct mem_cgroup {
/* thresholds for mem+swap usage. RCU-protected */
struct mem_cgroup_threshold_ary *memsw_thresholds;
+ /* For oom notifier event fd */
+ struct list_head oom_notify;
+
/*
* Should we move charges of a task when a task is moved into this
* mem_cgroup ? And what type of charges should we move ?
@@ -282,9 +292,12 @@ enum charge_type {
/* for encoding cft->private value on file */
#define _MEM (0)
#define _MEMSWAP (1)
+#define _OOM_TYPE (2)
#define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
#define MEMFILE_TYPE(val) (((val) >> 16) & 0xffff)
#define MEMFILE_ATTR(val) ((val) & 0xffff)
+/* Used for OOM nofiier */
+#define OOM_CONTROL (0)
/*
* Reclaim flags for mem_cgroup_hierarchical_reclaim
@@ -1353,6 +1366,8 @@ bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask)
*/
if (!locked)
prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
+ else
+ mem_cgroup_oom_notify(mem);
mutex_unlock(&memcg_oom_mutex);
if (locked)
@@ -3398,8 +3413,22 @@ static int compare_thresholds(const void *a, const void *b)
return _a->threshold - _b->threshold;
}
-static int mem_cgroup_register_event(struct cgroup *cgrp, struct cftype *cft,
- struct eventfd_ctx *eventfd, const char *args)
+static int mem_cgroup_oom_notify_cb(struct mem_cgroup *mem, void *data)
+{
+ struct mem_cgroup_eventfd_list *ev;
+
+ list_for_each_entry(ev, &mem->oom_notify, list)
+ eventfd_signal(ev->eventfd, 1);
+ return 0;
+}
+
+static void mem_cgroup_oom_notify(struct mem_cgroup *mem)
+{
+ mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_notify_cb);
+}
+
+static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
+ struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
{
struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
struct mem_cgroup_threshold_ary *thresholds, *thresholds_new;
@@ -3483,8 +3512,8 @@ unlock:
return ret;
}
-static int mem_cgroup_unregister_event(struct cgroup *cgrp, struct cftype *cft,
- struct eventfd_ctx *eventfd)
+static int mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
+ struct cftype *cft, struct eventfd_ctx *eventfd)
{
struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
struct mem_cgroup_threshold_ary *thresholds, *thresholds_new;
@@ -3568,13 +3597,61 @@ unlock:
return ret;
}
+static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
+ struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+ struct mem_cgroup_eventfd_list *event;
+ int type = MEMFILE_TYPE(cft->private);
+
+ BUG_ON(type != _OOM_TYPE);
+ event = kmalloc(sizeof(*event), GFP_KERNEL);
+ if (!event)
+ return -ENOMEM;
+
+ mutex_lock(&memcg_oom_mutex);
+
+ event->eventfd = eventfd;
+ list_add(&event->list, &memcg->oom_notify);
+
+ /* already in OOM ? */
+ if (atomic_read(&memcg->oom_lock))
+ eventfd_signal(eventfd, 1);
+ mutex_unlock(&memcg_oom_mutex);
+
+ return 0;
+}
+
+static int mem_cgroup_oom_unregister_event(struct cgroup *cgrp,
+ struct cftype *cft, struct eventfd_ctx *eventfd)
+{
+ struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
+ struct mem_cgroup_eventfd_list *ev, *tmp;
+ int type = MEMFILE_TYPE(cft->private);
+
+ BUG_ON(type != _OOM_TYPE);
+
+ mutex_lock(&memcg_oom_mutex);
+
+ list_for_each_entry_safe(ev, tmp, &mem->oom_notify, list) {
+ if (ev->eventfd == eventfd) {
+ list_del(&ev->list);
+ kfree(ev);
+ }
+ }
+
+ mutex_unlock(&memcg_oom_mutex);
+
+ return 0;
+}
+
static struct cftype mem_cgroup_files[] = {
{
.name = "usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
.read_u64 = mem_cgroup_read,
- .register_event = mem_cgroup_register_event,
- .unregister_event = mem_cgroup_unregister_event,
+ .register_event = mem_cgroup_usage_register_event,
+ .unregister_event = mem_cgroup_usage_unregister_event,
},
{
.name = "max_usage_in_bytes",
@@ -3623,6 +3700,12 @@ static struct cftype mem_cgroup_files[] = {
.read_u64 = mem_cgroup_move_charge_read,
.write_u64 = mem_cgroup_move_charge_write,
},
+ {
+ .name = "oom_control",
+ .register_event = mem_cgroup_oom_register_event,
+ .unregister_event = mem_cgroup_oom_unregister_event,
+ .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
+ },
};
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
@@ -3631,8 +3714,8 @@ static struct cftype memsw_cgroup_files[] = {
.name = "memsw.usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
.read_u64 = mem_cgroup_read,
- .register_event = mem_cgroup_register_event,
- .unregister_event = mem_cgroup_unregister_event,
+ .register_event = mem_cgroup_usage_register_event,
+ .unregister_event = mem_cgroup_usage_unregister_event,
},
{
.name = "memsw.max_usage_in_bytes",
@@ -3878,6 +3961,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
}
mem->last_scanned_child = 0;
spin_lock_init(&mem->reclaim_param_lock);
+ INIT_LIST_HEAD(&mem->oom_notify);
if (parent)
mem->swappiness = get_swappiness(parent);
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