Cgroup v1 supports a complicated OOM handling in userspace mechanism,
which is not supported by cgroup v2. Let's move the corresponding code
into memcontrol-v1.c.
Aside from mechanical code movement this patch introduces two new
functions: memcg1_oom_prepare() and memcg1_oom_finish().
Those are implementing cgroup v1-specific parts of the common memcg
OOM handling path.
Signed-off-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
---
mm/memcontrol-v1.c | 229 ++++++++++++++++++++++++++++++++++++++++++++-
mm/memcontrol-v1.h | 3 +-
mm/memcontrol.c | 216 +-----------------------------------------
3 files changed, 231 insertions(+), 217 deletions(-)
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index 8b8c2c9516349..6188b33ba03db 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -110,7 +110,13 @@ struct mem_cgroup_event {
struct work_struct remove;
};
-extern spinlock_t memcg_oom_lock;
+#ifdef CONFIG_LOCKDEP
+static struct lockdep_map memcg_oom_lock_dep_map = {
+ .name = "memcg_oom_lock",
+};
+#endif
+
+DEFINE_SPINLOCK(memcg_oom_lock);
static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz,
struct mem_cgroup_tree_per_node *mctz,
@@ -1469,7 +1475,7 @@ static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
return 0;
}
-void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
+static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
{
struct mem_cgroup *iter;
@@ -1959,6 +1965,225 @@ void memcg1_css_offline(struct mem_cgroup *memcg)
spin_unlock_irq(&memcg->event_list_lock);
}
+/*
+ * Check OOM-Killer is already running under our hierarchy.
+ * If someone is running, return false.
+ */
+static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *iter, *failed = NULL;
+
+ spin_lock(&memcg_oom_lock);
+
+ for_each_mem_cgroup_tree(iter, memcg) {
+ if (iter->oom_lock) {
+ /*
+ * this subtree of our hierarchy is already locked
+ * so we cannot give a lock.
+ */
+ failed = iter;
+ mem_cgroup_iter_break(memcg, iter);
+ break;
+ } else
+ iter->oom_lock = true;
+ }
+
+ if (failed) {
+ /*
+ * OK, we failed to lock the whole subtree so we have
+ * to clean up what we set up to the failing subtree
+ */
+ for_each_mem_cgroup_tree(iter, memcg) {
+ if (iter == failed) {
+ mem_cgroup_iter_break(memcg, iter);
+ break;
+ }
+ iter->oom_lock = false;
+ }
+ } else
+ mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_);
+
+ spin_unlock(&memcg_oom_lock);
+
+ return !failed;
+}
+
+static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *iter;
+
+ spin_lock(&memcg_oom_lock);
+ mutex_release(&memcg_oom_lock_dep_map, _RET_IP_);
+ for_each_mem_cgroup_tree(iter, memcg)
+ iter->oom_lock = false;
+ spin_unlock(&memcg_oom_lock);
+}
+
+static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *iter;
+
+ spin_lock(&memcg_oom_lock);
+ for_each_mem_cgroup_tree(iter, memcg)
+ iter->under_oom++;
+ spin_unlock(&memcg_oom_lock);
+}
+
+static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *iter;
+
+ /*
+ * Be careful about under_oom underflows because a child memcg
+ * could have been added after mem_cgroup_mark_under_oom.
+ */
+ spin_lock(&memcg_oom_lock);
+ for_each_mem_cgroup_tree(iter, memcg)
+ if (iter->under_oom > 0)
+ iter->under_oom--;
+ spin_unlock(&memcg_oom_lock);
+}
+
+static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
+
+struct oom_wait_info {
+ struct mem_cgroup *memcg;
+ wait_queue_entry_t wait;
+};
+
+static int memcg_oom_wake_function(wait_queue_entry_t *wait,
+ unsigned mode, int sync, void *arg)
+{
+ struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
+ struct mem_cgroup *oom_wait_memcg;
+ struct oom_wait_info *oom_wait_info;
+
+ oom_wait_info = container_of(wait, struct oom_wait_info, wait);
+ oom_wait_memcg = oom_wait_info->memcg;
+
+ if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) &&
+ !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg))
+ return 0;
+ return autoremove_wake_function(wait, mode, sync, arg);
+}
+
+void memcg_oom_recover(struct mem_cgroup *memcg)
+{
+ /*
+ * For the following lockless ->under_oom test, the only required
+ * guarantee is that it must see the state asserted by an OOM when
+ * this function is called as a result of userland actions
+ * triggered by the notification of the OOM. This is trivially
+ * achieved by invoking mem_cgroup_mark_under_oom() before
+ * triggering notification.
+ */
+ if (memcg && memcg->under_oom)
+ __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
+}
+
+/**
+ * mem_cgroup_oom_synchronize - complete memcg OOM handling
+ * @handle: actually kill/wait or just clean up the OOM state
+ *
+ * This has to be called at the end of a page fault if the memcg OOM
+ * handler was enabled.
+ *
+ * Memcg supports userspace OOM handling where failed allocations must
+ * sleep on a waitqueue until the userspace task resolves the
+ * situation. Sleeping directly in the charge context with all kinds
+ * of locks held is not a good idea, instead we remember an OOM state
+ * in the task and mem_cgroup_oom_synchronize() has to be called at
+ * the end of the page fault to complete the OOM handling.
+ *
+ * Returns %true if an ongoing memcg OOM situation was detected and
+ * completed, %false otherwise.
+ */
+bool mem_cgroup_oom_synchronize(bool handle)
+{
+ struct mem_cgroup *memcg = current->memcg_in_oom;
+ struct oom_wait_info owait;
+ bool locked;
+
+ /* OOM is global, do not handle */
+ if (!memcg)
+ return false;
+
+ if (!handle)
+ goto cleanup;
+
+ owait.memcg = memcg;
+ owait.wait.flags = 0;
+ owait.wait.func = memcg_oom_wake_function;
+ owait.wait.private = current;
+ INIT_LIST_HEAD(&owait.wait.entry);
+
+ prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
+ mem_cgroup_mark_under_oom(memcg);
+
+ locked = mem_cgroup_oom_trylock(memcg);
+
+ if (locked)
+ mem_cgroup_oom_notify(memcg);
+
+ schedule();
+ mem_cgroup_unmark_under_oom(memcg);
+ finish_wait(&memcg_oom_waitq, &owait.wait);
+
+ if (locked)
+ mem_cgroup_oom_unlock(memcg);
+cleanup:
+ current->memcg_in_oom = NULL;
+ css_put(&memcg->css);
+ return true;
+}
+
+
+bool memcg1_oom_prepare(struct mem_cgroup *memcg, bool *locked)
+{
+ /*
+ * We are in the middle of the charge context here, so we
+ * don't want to block when potentially sitting on a callstack
+ * that holds all kinds of filesystem and mm locks.
+ *
+ * cgroup1 allows disabling the OOM killer and waiting for outside
+ * handling until the charge can succeed; remember the context and put
+ * the task to sleep at the end of the page fault when all locks are
+ * released.
+ *
+ * On the other hand, in-kernel OOM killer allows for an async victim
+ * memory reclaim (oom_reaper) and that means that we are not solely
+ * relying on the oom victim to make a forward progress and we can
+ * invoke the oom killer here.
+ *
+ * Please note that mem_cgroup_out_of_memory might fail to find a
+ * victim and then we have to bail out from the charge path.
+ */
+ if (READ_ONCE(memcg->oom_kill_disable)) {
+ if (current->in_user_fault) {
+ css_get(&memcg->css);
+ current->memcg_in_oom = memcg;
+ }
+ return false;
+ }
+
+ mem_cgroup_mark_under_oom(memcg);
+
+ *locked = mem_cgroup_oom_trylock(memcg);
+
+ if (*locked)
+ mem_cgroup_oom_notify(memcg);
+
+ mem_cgroup_unmark_under_oom(memcg);
+
+ return true;
+}
+
+void memcg1_oom_finish(struct mem_cgroup *memcg, bool locked)
+{
+ if (locked)
+ mem_cgroup_oom_unlock(memcg);
+}
+
static int __init memcg1_init(void)
{
int node;
diff --git a/mm/memcontrol-v1.h b/mm/memcontrol-v1.h
index ef1b7037cbdcc..3de956b2422f1 100644
--- a/mm/memcontrol-v1.h
+++ b/mm/memcontrol-v1.h
@@ -87,9 +87,10 @@ enum res_type {
bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
enum mem_cgroup_events_target target);
unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap);
-void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
ssize_t memcg_write_event_control(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off);
+bool memcg1_oom_prepare(struct mem_cgroup *memcg, bool *locked);
+void memcg1_oom_finish(struct mem_cgroup *memcg, bool locked);
#endif /* __MM_MEMCONTROL_V1_H */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c14b1b01bcf53..3b088e0078821 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1616,130 +1616,6 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
return ret;
}
-#ifdef CONFIG_LOCKDEP
-static struct lockdep_map memcg_oom_lock_dep_map = {
- .name = "memcg_oom_lock",
-};
-#endif
-
-DEFINE_SPINLOCK(memcg_oom_lock);
-
-/*
- * Check OOM-Killer is already running under our hierarchy.
- * If someone is running, return false.
- */
-static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *iter, *failed = NULL;
-
- spin_lock(&memcg_oom_lock);
-
- for_each_mem_cgroup_tree(iter, memcg) {
- if (iter->oom_lock) {
- /*
- * this subtree of our hierarchy is already locked
- * so we cannot give a lock.
- */
- failed = iter;
- mem_cgroup_iter_break(memcg, iter);
- break;
- } else
- iter->oom_lock = true;
- }
-
- if (failed) {
- /*
- * OK, we failed to lock the whole subtree so we have
- * to clean up what we set up to the failing subtree
- */
- for_each_mem_cgroup_tree(iter, memcg) {
- if (iter == failed) {
- mem_cgroup_iter_break(memcg, iter);
- break;
- }
- iter->oom_lock = false;
- }
- } else
- mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_);
-
- spin_unlock(&memcg_oom_lock);
-
- return !failed;
-}
-
-static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *iter;
-
- spin_lock(&memcg_oom_lock);
- mutex_release(&memcg_oom_lock_dep_map, _RET_IP_);
- for_each_mem_cgroup_tree(iter, memcg)
- iter->oom_lock = false;
- spin_unlock(&memcg_oom_lock);
-}
-
-static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *iter;
-
- spin_lock(&memcg_oom_lock);
- for_each_mem_cgroup_tree(iter, memcg)
- iter->under_oom++;
- spin_unlock(&memcg_oom_lock);
-}
-
-static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *iter;
-
- /*
- * Be careful about under_oom underflows because a child memcg
- * could have been added after mem_cgroup_mark_under_oom.
- */
- spin_lock(&memcg_oom_lock);
- for_each_mem_cgroup_tree(iter, memcg)
- if (iter->under_oom > 0)
- iter->under_oom--;
- spin_unlock(&memcg_oom_lock);
-}
-
-static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
-
-struct oom_wait_info {
- struct mem_cgroup *memcg;
- wait_queue_entry_t wait;
-};
-
-static int memcg_oom_wake_function(wait_queue_entry_t *wait,
- unsigned mode, int sync, void *arg)
-{
- struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
- struct mem_cgroup *oom_wait_memcg;
- struct oom_wait_info *oom_wait_info;
-
- oom_wait_info = container_of(wait, struct oom_wait_info, wait);
- oom_wait_memcg = oom_wait_info->memcg;
-
- if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) &&
- !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg))
- return 0;
- return autoremove_wake_function(wait, mode, sync, arg);
-}
-
-void memcg_oom_recover(struct mem_cgroup *memcg)
-{
- /*
- * For the following lockless ->under_oom test, the only required
- * guarantee is that it must see the state asserted by an OOM when
- * this function is called as a result of userland actions
- * triggered by the notification of the OOM. This is trivially
- * achieved by invoking mem_cgroup_mark_under_oom() before
- * triggering notification.
- */
- if (memcg && memcg->under_oom)
- __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
-}
-
/*
* Returns true if successfully killed one or more processes. Though in some
* corner cases it can return true even without killing any process.
@@ -1753,104 +1629,16 @@ static bool mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
memcg_memory_event(memcg, MEMCG_OOM);
- /*
- * We are in the middle of the charge context here, so we
- * don't want to block when potentially sitting on a callstack
- * that holds all kinds of filesystem and mm locks.
- *
- * cgroup1 allows disabling the OOM killer and waiting for outside
- * handling until the charge can succeed; remember the context and put
- * the task to sleep at the end of the page fault when all locks are
- * released.
- *
- * On the other hand, in-kernel OOM killer allows for an async victim
- * memory reclaim (oom_reaper) and that means that we are not solely
- * relying on the oom victim to make a forward progress and we can
- * invoke the oom killer here.
- *
- * Please note that mem_cgroup_out_of_memory might fail to find a
- * victim and then we have to bail out from the charge path.
- */
- if (READ_ONCE(memcg->oom_kill_disable)) {
- if (current->in_user_fault) {
- css_get(&memcg->css);
- current->memcg_in_oom = memcg;
- }
+ if (!memcg1_oom_prepare(memcg, &locked))
return false;
- }
-
- mem_cgroup_mark_under_oom(memcg);
- locked = mem_cgroup_oom_trylock(memcg);
-
- if (locked)
- mem_cgroup_oom_notify(memcg);
-
- mem_cgroup_unmark_under_oom(memcg);
ret = mem_cgroup_out_of_memory(memcg, mask, order);
- if (locked)
- mem_cgroup_oom_unlock(memcg);
+ memcg1_oom_finish(memcg, locked);
return ret;
}
-/**
- * mem_cgroup_oom_synchronize - complete memcg OOM handling
- * @handle: actually kill/wait or just clean up the OOM state
- *
- * This has to be called at the end of a page fault if the memcg OOM
- * handler was enabled.
- *
- * Memcg supports userspace OOM handling where failed allocations must
- * sleep on a waitqueue until the userspace task resolves the
- * situation. Sleeping directly in the charge context with all kinds
- * of locks held is not a good idea, instead we remember an OOM state
- * in the task and mem_cgroup_oom_synchronize() has to be called at
- * the end of the page fault to complete the OOM handling.
- *
- * Returns %true if an ongoing memcg OOM situation was detected and
- * completed, %false otherwise.
- */
-bool mem_cgroup_oom_synchronize(bool handle)
-{
- struct mem_cgroup *memcg = current->memcg_in_oom;
- struct oom_wait_info owait;
- bool locked;
-
- /* OOM is global, do not handle */
- if (!memcg)
- return false;
-
- if (!handle)
- goto cleanup;
-
- owait.memcg = memcg;
- owait.wait.flags = 0;
- owait.wait.func = memcg_oom_wake_function;
- owait.wait.private = current;
- INIT_LIST_HEAD(&owait.wait.entry);
-
- prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
- mem_cgroup_mark_under_oom(memcg);
-
- locked = mem_cgroup_oom_trylock(memcg);
-
- if (locked)
- mem_cgroup_oom_notify(memcg);
-
- schedule();
- mem_cgroup_unmark_under_oom(memcg);
- finish_wait(&memcg_oom_waitq, &owait.wait);
-
- if (locked)
- mem_cgroup_oom_unlock(memcg);
-cleanup:
- current->memcg_in_oom = NULL;
- css_put(&memcg->css);
- return true;
-}
-
/**
* mem_cgroup_get_oom_group - get a memory cgroup to clean up after OOM
* @victim: task to be killed by the OOM killer
--
2.45.1
